Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download InfoComm Glossary
Document related concepts
Alternating current wikipedia , lookup
Mains electricity wikipedia , lookup
Phone connector (audio) wikipedia , lookup
Electronic musical instrument wikipedia , lookup
Electromagnetic compatibility wikipedia , lookup
Pulse-width modulation wikipedia , lookup
Dynamic range compression wikipedia , lookup
Electronic engineering wikipedia , lookup
Earthing system wikipedia , lookup
Resistive opto-isolator wikipedia , lookup
Distribution management system wikipedia , lookup
Oscilloscope history wikipedia , lookup
Ground (electricity) wikipedia , lookup
Ground loop (electricity) wikipedia , lookup
Sound reinforcement system wikipedia , lookup
Telecommunications engineering wikipedia , lookup
Transcript
InfoComm Glossary V.201501 TABLE OF CONTENTS # ..................................................................................................................................1 A ..................................................................................................................................3 B ................................................................................................................................14 C ................................................................................................................................20 D ................................................................................................................................37 E ................................................................................................................................51 F ................................................................................................................................57 G ...............................................................................................................................64 H ................................................................................................................................69 I .................................................................................................................................76 J ................................................................................................................................83 K ................................................................................................................................84 L ................................................................................................................................84 M ...............................................................................................................................90 N ................................................................................................................................97 O ............................................................................................................................. 102 P .............................................................................................................................. 106 Q ............................................................................................................................. 118 R .............................................................................................................................. 119 S .............................................................................................................................. 130 T .............................................................................................................................. 147 U .............................................................................................................................. 154 V .............................................................................................................................. 156 W ............................................................................................................................. 160 X .............................................................................................................................. 163 Y .............................................................................................................................. 163 Z .............................................................................................................................. 164 Sources ................................................................................................................... 165 -i- # 1/3 Octave Equalizer A 1/3 octave equalizer is a graphic equalizer that provides 30 or 31 slider adjustments corresponding to specific fixed frequencies with fixed bandwidths, with the frequencies centered at every one-third of an octave. The numerous adjustment points shape the overall frequency response of the system. This makes the sound system sound more natural. 1/4-inch Phone Connector A 1/4 inch phone connector is typically used to transport audio signals from one audio processing device to another. 1/8-inch Phone Connector A 1/8 inch phone connector is commonly used to carry mono and stereo audio, microphone, or control signals. -1- 2-way / 3-way Loudspeaker with Passive Crossover 2-way, 3-way loudspeakers with Passive Crossover are usually cabinet units with multiple (2 or 3 or even 4) loudspeaker types included. The individual loudspeakers respond to different portions of the audible frequency range and the crossover acts as the dividing component that sends the appropriate energy to the right loudspeaker. Crossovers may be passive (handling speaker level signals from a single amplifier) or active (processing line level signals and feeding them to multiple power amplifiers, called bi- or tri-amplification). 3.5 mm Mini A connector that is similar in appearance to a 1/4-inch phone connector, but much smaller. It measures 3.5 mm in diameter. 3D Display A 3D (three-dimensional) display allows viewers to perceive depth in images/video recorded in 3D and played back on a 3D capable media player. Stereoscopic 3D displays require 3D glasses for viewing images in 3D. Media recorded in 3D can also be viewed on autostereoscopic 3D flat-screen LCD displays without 3D glasses. 4-pin Modular Connector (RJ-11) Used in the United States to connect a basic telephone. Male RJ-11 connectors are designed to fit into the female connector, which is typically installed on a wall. A small clip prevents the connector from becoming accidentally disconnected. Press down on this clip before separating the connectors. -2- 4K 4K video cameras, media players, and displays enable the recording and display of video at 3840x2160-pixel resolution. This is also often called Ultra HD. 8-pin Modular Connector (RJ-45) An 8-pin modular connector is a connector used to terminate 8 wire cables via insulation displacement. 8-pin modular connectors are commonly referred to as Ethernet, RJ45, 8P8C, or 8P2C connectors. They are commonly used in local area networking, HDBaseT, and other digital AV applications. 8K 8K is an Ultra HD format. It has a 7680 x 4320 pixel resolution, which is 16 times the resolution of Full HD. 9-pin Connector The 9-pin connector is the most common type of RS-232 connection that is used within a control system. A Acceptable Viewing Area The area beyond the optimal viewing area for a display screen demarcated by lines extending outward at 45-degree angles from the right and left edges of the displayed image, as opposed to the 45-degree angles from the center of the display image that makes up the optimal viewing area. -3- Access Point An access point is a network device that handles a wireless network connection. Accounting Accounting is an administrative office that pays the organization's bills and invoices customers. The staff may also negotiate prices and payment terms and purchase products for the office. Accounting is also known as "Accounts Receivable," or "Accounts Payable." Account Manager An Account Manager handles all sales and serves as a contact to specific customers. Acoustic Echo Canceller A device used in a conferencing system that will attempt to compensate for environmental echoes (delayed audio) which are created by the far-site sound bouncing off the walls and furniture, and returned to the microphones. Acoustician Acousticians are professional experts that advise design teams on acoustics. Acoustics Acoustics is the science and technology of sound in all its aspects. Acoustics covers sound production, propagation and control; its interaction with materials; its reception by the ear, and its effects on the hearer. 1 Active System An active system is a system that requires power. -4- Activity An activity is a specific end result of an AV system communicated by the operator (user) of an AV space. An example would be a user wants to watch a DVD. Acuity Acuity is an eye's ability to discern fine details. There are several different kinds of acuity, including: 1. Resolution acuity - the ability to detect that there are two stimuli, rather than one, in the visual field. It is measured in terms of the smallest angular separation between two stimuli that can still be seen as separate. 2. Recognition acuity - the ability to correctly identify a visual target, as in differentiating between a “G” and a “C.” Usually, but not always, it is measured in terms of the angular dimension of the smallest target that can be discriminated. A clinical eye chart, where visual acuity testing performed using letters, as is done clinically, is a form of recognition acuity testing. Recognition acuity can involve very complex perceptual processing and often cannot be simply related to resolution acuity. Although detecting the difference between an “O” and a “C” may be identical to resolution acuity, differentiating between a circle and an octagon is a more complex task. Furthermore, the polarity (bright on dark versus dark on bright) can affect the result. For example, dark-on-bright discriminations are often more appropriately considered contrast detection tasks than visual acuity tasks. 2 Adapters Adapters are used as interfaces in audiovisual technology to change from type of connector, signal format or power source to another. Address Resolution Protocol (ARP) Address Resolution Protocol is a TCP/IP protocol defined in the IETF standard RFC 826. The purpose of ARP is to resolve logical IP addresses to physical MAC addresses. ARP falls under the Link Layer of the TCP/IP protocol stack and the Data Link Layer of the OSI model. -5- Administrative Office An administrative office ensures that your organization operates smoothly. Alternating Current (AC) Alternating current (AC) is an electric current that reverses its direction periodically. Algorithm An algorithm is a way to break down instructions for computing machines in a highly organized manner. Allied Trade An Allied Trade is a business that collaborates with AV professionals to complete a project. Ambient Light Lighting throughout an area that produces general illumination. 3 Ambient Light on Screen The illuminance level affecting the projection screen. Ambient Noise Ambient noise is the sound that is extraneous to the intended, desired, or intentional background noise. Amplifier An amplifier is an electronic device for increasing the strength of electrical signals. -6- Amplitude Amplitude is the strength of a signal as measured by the height of its waveform. Amperage Amperage refers to the amount of electric current flow within a circuit. Amperage is measurement in "Amps," and expressed using the symbols I or A. Analog Analog is a method of transmitting information by a continuous but varying signal. Analog Signal Analog Signal is represented as a continuous, varying wave. Analog-to-Digital or Digital-to-Analog Converter (AD / DA) Analog-to-Digital or Digital-to-Analog (AD/DA) converters are used to convert signals from analog to digital or from digital to analog. Analog Voltage Control Analog voltage control uses a variable voltage to proportionally regulate another protocol. Analog voltages can be positive or negative or both, high voltage or low voltage, fast or slow, modulated or DC. Angle of View Angle of view is how much of a scene is visible in a camera output. Focal length along with the imager dimensions determine the angle of view. -7- Angularly Reflective Screen An angularly reflective screen is a screen that reflects light back to the viewer at a complementary angle. Annotation Annotation allows a presenter to mark up a displayed image as a means of highlighting specific information. Annotation technologies include interactive pens & displays, whiteboards, handheld tablet devices, touch-sensitive screens and more. ANSI ANSI stands for American National Standards Institute. ANSI Contrast Contrast ratio as measured using the procedure adopted by the American National Standards Institute (ANSI) and the International Electrotechnical Commission (IEC). Measured using a "checkerboard" test pattern of 16-zone alternating black and white rectangles. Aperture An aperture is an opening in a lens regulating the amount of light passing through the lens to the imager. Appliance Digital signage appliances are processing devices that support networks or help manage distribution or playback of digital signage across multiple screens or devices. Application In the context of a needs analysis, an application is an activity or process that supports the end user's communication need(s). -8- Arc-Minute An arc-minute is 1/60 of one degree of a 360-degree circle. One minute of arc is about the smallest angle of vision over which the normal human eye can resolve an object, under ideal conditions of contrast, brightness, ambient light, and signal-to-noise ratio. Archival system Archival systems are equipment-based systems designed to ingest, organize & access multiformat rich-media content. Arrayed Loudspeaker System Arrayed loudspeaker system delivers sound from a single point in space. It is also known as a "high-pressure systems." Artifact Artifacts are small disturbances that affect the quality of a signal. Aspect Ratio Aspect ratio is the ratio of image width to image height. It can be expressed as two whole numbers separated by a colon, e.g. 16:9, or by the decimal equivalent of the implied division, e.g. 1.77. Common video aspect ratios include the following: • 4:3 (1.33) for Standard-Definition (SD) video very common in late 20th century • 16:9 (1.77) for High-Definition (HD) video • Some computer and video production displays added space below the 16:9 aspect ratio of HD video and made a 16:10 (1.6) aspect ratio. Assistive Listening Device Assistive listening devices provide enhancement of sound for people who are hard of hearing. The Americans with Disabilities Act mandates the use of assistive listening devices in certain environments. -9- ATA Shipping Cases ATA shipping cases are road cases which follow Air Transport Association specifications certified for airline shipping. Attack Time The attack time of an audio digital signal processor determines how quickly the volume will be reduced once the volume exceeds the threshold. If the attack time is too slow, then the sound will become distorted as the system adjusts. Attack Vector An attack vector is the means by which a malicious program or unauthorized user gains access to a system. Attenuate To attenuate is to reduce the amplitude (strength) of a signal or current. Audience Response Systems Audience responses systems are devices that tabulate results when presenters ask questions & audience members to respond or vote by pushing buttons. Audioconferencing Audioconferencing, or teleconferencing, allows multiple groups to communicate by audio over long distances. Audioconferencing is often used in conjunction with videoconferencing. Audioconference data may travel over ISDN, IP or POTS. Audio Coverage Uniformity Measurement Locations (ACUML) The test points within a venue that have been determined to carry out the measurements for the Audio Coverage Uniformity test. - 10 - Audio Coverage Uniformity Plan (ACUP) A stand-alone document that identifies the Audio Coverage Uniformity measurement locations for a particular venue, using the InfoComm indication symbol. Audio Engineering Society (AES) AES stands for Audio Engineering Society. Audio Feed Audio feeds are used to route the audio signal to other rooms or remote destinations. Audio Processor An audio processor is an electronic device used to manipulate audio signals in some manner. Audio Signal An audio signal is an electrical representation of sound. Audio System An audio system allows users to reproduce, record, and amplify sound. Audio Transduction Audio transduction is converting acoustical energy into electrical energy, or electrical energy back into acoustical energy. Audio, Video, and Lighting Technicians Audio, Video, and Lighting Technicicans are technical professionals who perform contracted systems integrations or staging installations. They also operate equipment during live events. - 11 - Audiovisual (AV) System All equipment integrated into the energy-consuming infrastructure necessary to fulfill the intent of communicating audio and/or video content to an audience. A set of specified, individual audio and video components designed and configured to operate as one comprehensive system. Auditorium An auditorium is a room commonly used for delivering non-interactive presentations to large groups. It is used for diverse purposes such as school plays or assemblies. An auditorium normally has a stage or presentation platform with fixed seating radiating out from the presentation area. Authority Having Jurisdiction (AHJ) Authority Having Jurisdiction is an organization, office, or individual responsible for enforcing the requirements of a code or standard, or for approving equipment, materials, an installation, or a procedure. In some areas of the world, authority having jurisdiction is known as a "regional regulatory authority." Automatic Gain Control (AGC) Automatic gain control (AGC) is an electronic or logic feedback circuit that maintains a constant acoustic power (gain) output in response to input variables such as signal strength or ambient noise level. Automatic Private IP Addressing (APIPA) Automatic Private IP Addressing is a form of link-local addressing defined in the IETF standard RFC 3927. APIPA automatically assigns locally routable addresses from the reserved network 169.254.0.0/16 to devices that do not have or cannot obtain an IP address. This allows devices to communicate with other devices on the same LAN. APIPA operates at the Network Layer of the OSI model and the Internet Layer of the TCP/IP protocol stack. - 12 - Automation A method or product used to transition a component between two system states when one of the following conditions is detected: (1) device has ceased performance of all primary functions, (2) the last user interface command has been received (e.g., remote control, control system, physical human intervention), (3) a predetermined amount of time has elapsed, or (4) an established calendar or schedule is activated. AV Designer An AV Designer is a technical professional who documents customers' communication requirements, designs AV systems to meet those needs, and documents AV system designs. AV Infrastructure The AV infrastructure is the physical building components that make up the pathways, supports, and architectural elements required for audiovisual technical equipment installations. AV Rack An AV rack is a housing unit that protects and organizes electronic equipment. The inside of a typical AV industry rack is 19 inches (482.6 mm) wide. Many of the technical specifications for a rack, including size and equipment height, are determined by standards that have been established by numerous standard-setting organizations. The outside width of the rack varies from 21 to 25 inches (530 to 630 mm). AV Space An AV space is any environment equipped with audiovisual technology that addresses one or more audiovisual needs. AV Subsystem An AV subsystem is a piece of the larger system that only contributes to part of the communication objective. It is not until the AV subsystem is combined with a larger AV system that the full communication objective is met. - 13 - AV System An AV system is two or more pieces of AV equipment that work together to meet a communication need. AV System Programmer An AV System Programmer is a technical professional who writes software code for control systems and configures software-based AV devices. Audio Video Bridging (AVB) Audio Video Bridging (AVB) is a standards-based audiovisual Data Link Layer protocol defined under IEEE 802.1-AVB. It uses standard Ethernet cabling, but requires AVB-enabled switches and network components. AVB does not require separate network infrastructure or dedicated bandwidth; AVB components automatically prioritize data. B Background Music System A background music system serves to provide mostly subtle audio. This type of system is used in elevators, restaurants, malls, etc. Balanced Circuit A balanced circuit is a two-conductor circuit in which both conductors and all circuits connected to them have the same impedance with respect to ground. Balun Balun, short for BALanced-to-UNbalanced, is a transformer used to connect a balanced circuit to an unbalanced circuit. For example, a transformer used to connect a 300-ohm antenna cable (balanced) to a 75-ohm antenna cable (unbalanced). - 14 - Band Bands are a grouping or range of frequencies. Bandwidth Bandwidth is a measure of the amount of data or signal that can pass through a system during a given time interval. In the context of networking, bandwidth is the available or consumed data communication resources of a communication path, expressed in terms of bits per second. It is also called throughput or bit rate. Bandwidth Limiting Bandwidth limiting is the result of encoding a higher quality signal into a lower quality form, such as RGB converted into S-Video. Baseband Baseband is a video signal that has not been modulated. Baseline The initial measurement of power consumption recorded for each system state of an audiovisual system against which the basis of all change is measured. Benchmarking Benchmarking refers to the process of examining methods, techniques, and principles from peer organizations and facilities, which can be used as a basis for designing a new or renovated facility. - 15 - Bend Radius Bend radius is the radial measure of a curve in a conductor beyond which further bending has a measurable and/or negative effect on the signal being transported. Bend radius may be different in the same cable assembly depending on the signal type. Bi-directional Communication Bi-directional communication is a system that uses feedback to give users a status update on their devices. Bi-Directional Polar Pattern Bi-directional polar pattern is the shape of the region where some microphones will be most sensitive to sound from the front and rear, while rejecting sound from the top, bottom, and sides. Bill of Materials (BOM) A complete equipment list of components that must be procured in order to build the system as designed. The BOM lists the costs of components and materials needed to complete and implement the system. Binocular Vision Binocular Vision is the area where the visual field of two individual eyes overlaps. In this area, the central field is of greater magnitude than that possible by each eye separately. You can recognize words and symbols and interpret depth perception in this field. The binocular field is about 60° in each direction. 4 Bit Bit is the shortened form of binary digit, symbolized by 1s and 0s. It is the smallest unit of digital information. - 16 - Bit Error Rate (BER) The bit error rate (BER) is the total amount of error bits present in a signal after being sent across a cable. It is calculated by performing a BER test. 5 Bit Depth Bit depth is the number of bits used to describe a sampled voltage level. Bit depth is also known as "quantization" because it involves assigning a quantity to the signal being measured. Greater bit depth gives a more accurate representation of the sampled signal. Bit Rate Bit rate is the measurement of the quantity of information over time in a digital signal stream. The higher the bit rate, the better the signal quality will be. Bit Rate is quantified in bits per second (bit/s or bps). Blocking Blocking is pieces of wood that have been inserted between structural building elements to provide a secure mounting point for finish materials or products. Block Diagram In AV documentation, a block diagram is an illustration of the signal path through a given system. It maps the path of a signal from source to destination. It is also known as a signal flow schematic or an AV system flow diagram. Bluetooth Bluetooth is a wireless technology for low-cost, short-range radio links between mobile phones, computers, personal digital assistants (PDAs), and other consumer devices. It uses a short-range wireless connection WPAN (wireless personal area network), which allows devices with transceiver chips to talk to each other. - 17 - BNC Connector The BNC (Bayonet Neill–Concelman) connector is a termination for coaxial cable (RG-58, 59, to RG-179, RG-316), known for its reliability and ruggedness. BNCs are connected with a slight push and then a twist to lock them into place. They are used to transport many different types of signals such as radio, frequency, component video, time code, sync, and power. Boardroom A boardroom is a space in which interactive meetings are held, generally attended by the executives of a company. Often, boardrooms are defined by the scale and shape of the room table, which is often long and oblong. Bonding Bonding is a term for special measures taken to ensure that various components are electrically connected together by a low impedance connection, thus ensuring that they are of the same electrical potential (Giddings, pg 286). Bootstrap Protocol (BOOTP) Bootstrap Protocol (BOOTP) is an automatic IP address allocation protocol defined in the IETF standard RFC 951. When an enabled device boots up, it requests an address from the BOOTP server. BOOTP automatically assigns the device an IP address and network configuration parameters. BOOTP draws IP addresses and other network parameters from a manually created lookup table. BOOTP operates at the Network Layer of the OSI model and the Internet Layer of the TCP/IP protocol stack. Boundary Microphone A boundary microphone relies on reflected sound from a surrounding surface. A boundary microphone sits directly on a table or surface. They are also called "surface mount microphones." - 18 - The Box Sale Model The box sale model is a business model in which dealers solely focus on equipment sales. Branch Circuit A branch circuit is the circuit conductors between the final overcurrent device protecting the circuit and the outlet(s). 6 Breaker Box See Panelboard. Bridge A bridge is a network device or setting that connects multiple network segments along the physical and data link layers of the OSI model. It breaks up collision domains, where data packets collide. Only packets that are destined for a segment are forwarded to that segment. Brightness A subjective term for the way light intensity is perceived by the human visual system. Referring to our experience and impression of light, it is not a metric of its magnitude. As used in the ANSI/INFOCOMM 3M-2011 Standard, the term brightness is not to be confused with "brightness" controls on a projector. Brightness Brightness is the amount of light reflected or emitted from a display. Broadcast Domain A set of devices that can send Data Link Layer frames to each other directly, without passing through a Network Layer device. Broadcast traffic sent by one device in the broadcast domain is received by every device within the same domain. - 19 - Buffer Amplifier A buffer amplifier is an electronic device that provides some isolation between other components. Building Information Modeling (BIM) Building Information Modeling (BIM) is a data repository for building design, construction, and maintenance information, used by multiple trades on a single project. It includes CAD drawings, as well as information such as bid and contract documents, Bills of Materials (BOMs), timelines, specifications, price lists, installation and maintenance guides, cable lists, and cable label guidelines. 7 Bus A bus is a wiring system that delivers power and data to various devices. Busbar Busbar is an electrically conductive block or bar of metal, typically copper or aluminum, that serves as a common connection for two or more circuits. Buzz Buzz describes a mixture of higher order harmonics of the 60 Hz noise (hum) originating from the AC power system and audible in the sound system. Byte A byte is a group of eight bits. "B" is the abbreviation for byte. C C Signal The C signal is a combination of the R-Y and B-Y signals. C represents chrominance or chroma, meaning color. - 20 - Cable A cable is an assembly of more than one conductor (wire). Cable Tray A cable tray is an assembly of units made of metal or other noncombustible material to provide rigid continuous support for cables. Cache A cache is temporary local storage space for data that is used repeatedly. Caching Server A caching server is a type of proxy server that saves local copies of frequently or recently requested network resources. Caching servers have two benefits: they reduce latency by decreasing response time to repeated requests, and limit wide area bandwidth usage by keeping traffic within the local area network. CAD/BIM Operator A CAD/BIM operator is a technical professional who uses software programs to create computer models or drawings of the AV system design to show how it fits into the building. Camera Cameras are devices that capture visual information. These capture devices allow a large group to share the same viewing experience. Cameras can be routed to individual monitors, a single large screen display, streamed to a remote location, or recorded for future viewing. Candela A candela is the luminous intensity of a source that emits monochromatic radiation of frequency 540 × 1012 hertz, and has a radiant intensity in that direction of 1⁄683 watt per steradian. The candela has replaced the candlepower standard. - 21 - Candela per Meter Square Candela per square meter is the metric unit for measuring the luminance of a surface area. It is abbreviated as cd/m2. These units are sometimes known as "nits." Capacitance Capacitance is the ability of a non-conductive material to develop an electrical charge, which can distort an electrical signal. Capacitive Reactance Capacitive reactance is the opposition a capacitor offers to alternating current flow. Capacitive reactance decreases with increasing frequency or, for a given frequency; the capacitive reactance decreases with increasing capacitance. The symbol for capacitive reactance is X C . Capacitor A capacitor is a passive electrical component in which plates of conductive material are separated by a dielectric. For a given capacitance value, expressed in farads, a capacitor will have a greater opposition to AC current flow at lower frequencies than at higher frequencies. This property is known as capacitive reactance. Captive Screw Connector Captive screw connector, sometimes called a Phoenix( R ) or Euro-block connector, is a molded plastic connector. Termination requires a wire to be stripped and slid directly into a slot on the connector. A set screw then pushes a gate down to hold the wire in place. Capital Expenditure (Capex) Capital expenditure refers to expenses a business incurs to create future benefits, such as purchasing new buildings, or improvements and additions to existing facilities. - 22 - Card Readers Card readers are learning aids that allow users to swipe magnetic vocabulary cards in a reader which translates the data into spoken audio. Cardioid Cardioid is a heart-shaped region where some microphones will be most sensitive to sound predominately from the front of the microphone diaphragm and reject sound coming from the sides and rear. Carrier Carrier is a modulated frequency that carries video or audio signals. Casework Casework is similar to furniture, with the distinction that casework is built into the room. Casework includes such items as cabinets, credenzas, benches, and podiums. Category 5 Cable (Cat 5) Category 5 (CAT 5) is the designation for 100-ohm unshielded twisted-pair cables and associated connecting hardware whose characteristics are specified for data transmission up to 100 Mb/s. (Part of the EIA/TIA 568A standard.) Category 5e Cable (Cat 5e) Category 5e (CAT 5e) is an enhanced version of the CAT-5 cable standard that adds specifications for far-end crosstalk. (Part of the EIA/TIA 568A standard.) Category 6 (CAT 6) Category 6 (CAT 6) is a cable standard for Gigabit Ethernet and other interconnect that is backward compatible with Category 5 cable, CAT-5e and CAT-3. CAT-6 features more stringent specifications for crosstalk and system noise. (Part of the EIA/TIA 568A standard.) - 23 - Cathode Ray Tube (CRT) CRT or Cathode Ray Tube is the video display tube used in monitors and receivers, radar displays and video computer displays. The CRT is a high-vacuum tube containing an electron gun to produce the images seen on the face of the tube. Central Cluster Central cluster is a single source configuration of loudspeakers. In a central cluster, the sound is coming from one point in the room. The central cluster is normally located directly above (on the proscenium), and slightly in front of, the primary microphone location. Central Processing Unit (CPU) CPU, or Central Processing Unit, is the portion of a computer system that reads and executes commands. Center Line A notional horizontal or vertical line that bisects the screen, referenced in the example Viewing Area Plans provided in the ANSI/INFOCOMM 3M-2011 Standard. Used for defining location of objects relative to the screen. Center Tap Center tap is a connection point located half way along the winding of a transformer or inductor. Charged-Coupled Device (CCD) A Charged-Couple Device (CCD) is a semiconductor image-sensing device, commonly used in video and digital cameras, that converts optical images into electronic signals. - 24 - Chassis Chassis is an enclosure that houses electronic equipment and is frequently electrically conductive (metal). The metal enclosure acts as a shield and is connected to the equipment grounding conductor of the AC power cable, if so equipped, in order to provide protection against electric shock. Also called a cabinet or frame. Chassis Ground Chassis ground is the 0V (zero volt) connection point of any electrically conductive chassis or enclosure surrounding an electronic device. This connection point may or may not be extended to the earth ground. Chroma Chroma is the saturation, or intensity, of a specific color. It is one of the three attributes that define a color; the other two are hue and grayscale. Chrominance Chrominance is the color portion of a composite or S-Video signal. CIA Triad The confidentiality, integrity, and availability (CIA) triad represents the three main considerations in identifying required security measures. Circuit Switching Circuit switching is a method of data transmission in which a dedicated communication channel is established between any two nodes prior to data transmission. - 25 - Circulation Space Circulation space is the amount of area a person needs to turn around without disturbing other people. According to Fruin, this area is 10 to 13 square feet, or 0.93 to 1.21 square meters per person. 8 Classful Under IPv4, a classful network is a network that includes every host address in a full class network range. The size of a classful network is determined by its default netmask. A classful network can accommodate either 16.7 million devices (Class A), 65,536 devices (Class B), or 256 devices (Class C). Classless Inter-Domain Routing (CIDR) Classless Inter-Domain Routing (CIDR) is a method of IP addressing that allows variable length subnet masks. As opposed to the classful system, under CIDR, a network of any size can be issued on an as-needed basis. Clean Ground (Ambiguous term to be avoided). Client A client is a device, computer, or workstation, typically with limited processing power, that depends on a server to perform certain functions. Clipping Clipping is the deformation of an audio signal when a device's peak amplitude level is exceeded. - 26 - Closed Circuit Television (CCTV) Closed circuit television (CCTV) is a system of transmitting video signals from the point of origin to single or multiple points equipped to receive signals. Closest Viewer Viewer positioned at the shortest distance from the screen as defined by the viewing area. Clue A clue is a visual cue that allows a viewer to fill in the elements that are not easily viewable. Cluster A cluster is a group of loudspeakers that are suspended to cover a wide area. Each component of the cluster will be aimed specifically at a portion of the audience. Clock Adjustment Clock adjustment is also called timing signals, used to fine tune the computer image. This function adjusts the clock frequencies that eliminate the vertical banding (lines) in the image. Cloud Computing Cloud computing is a networking strategy for deploying groups of remote servers and software networks to allow different data sources to be uploaded for real time processing. Clouds can be classified as public, private or hybrid. Coaxial Cable A coaxial cable is a cable consisting of a center conductor surrounded by insulating material, concentric outer conductor, and optional protective covering, all of circular cross-section. Abbreviated coax. - 27 - CobraNet CobraNet® is a proprietary digital audio Data Link Layer protocol designed by Cirrus Logic®. It uses standard Fast Ethernet cabling, switches, and other components. CobraNet signals are non-routable. Code A code is an extensive compilation of standards that cover a broad subject matter that is often suitable for adoption into law. CODEC (Coder/Decoder) CODEC is an acronym for coder/decoder. It is an electronic device that converts analog signals, such as video and audio signals, into digital form and compresses them to conserve bandwidth on a transmission path. Color Burst A color burst is that part of an NTSC video signal that carries the color information. It is a signal consisting of several (8 to 10 in NTSC) cycles of unmodulated color subcarriers, superimposed at a specified location within the composite signal. Color Difference Signals Color difference signals are signals which convey color information such as hue and saturation in a composite format. Two such signals are needed. These color difference signals are R-Y and B-Y, sometimes referred to as Pr and Pb or Cr and Cb. Color Rendering Index (CRI) The effect a light source has on the perceived color of objects relative to an incandescent source of the same correlated color temperature, which has a CRI of 100. 9 - 28 - Color Temperature Color temperature is the quantification of the color of "white" light, as rated on a numerical scale. Low color temperature light (~2000K) has a warm (red-ish) look while light with a high color temperature (~6000K) has a colder (blue-ish) appearance. Collision Domain A collision domain is a set of devices on a Local Area Network (LAN) whose packets may collide with one another if they send data at the same time. Comb Filter Comb filter is a transversal filter that combs out a specific set of frequencies. Comb filters are very effective in separating the chrominance and luminance sidebands in an NTSC video signal. Combiner In a process called multiplexing, the combiner puts signals together onto one cable constituting a broadband signal. Common Carrier Topology In a common carrier Wide Area Network (WAN) topology, each Local Area Network (LAN) site runs a spoke to an Internet Service Provider (ISP) backbone. - 29 - Common-Mode Common-mode refers to either noise or surge voltage disturbances occurring between the power neutral (white wire) and the grounding conductor (green wire). Unwanted common mode disturbances exist as a result of noise injection into the neutral or grounding wires, wiring faults, or overloaded power circuits. Common-Mode Rejection Ratio (CMRR) Common-mode rejection ratio (CMRR) is the ratio of the common-mode interference voltage at the input of a circuit, to the corresponding interference voltage at the output. Communications Security Communications security ensures information cannot be intercepted in intelligible form as it travels from one point to another. This can be done through encryption or providing a secure tunnel for the communication to travel over. Community Antenna Television (CATV) CATV stands for Community Antenna Television system. Broadcast signals are received by a centrally located antenna and distributed by cable through a region. Compander A compander is a device that combines compression and expansion. Component Video Color video in which the brightness (luminance) and color hue and saturation (chrominance) are handled independently. The red, green, and blue signals—or more commonly, the Y, R-Y, and B-Y signals—are carried by three separate wires. Because these signals are independent, processing such as chroma keying is facilitated. - 30 - Composite Video Signal Composite video signal is the electrical signal that represents complete color picture information and all synchronization signals, including blanking and the deflection synchronization signals to which the color synchronization signal is added in the appropriate time relationship. Compression In the context of networking, compression is a process that reduces very large files to smaller, manageable sizes. Compressed files discard unnecessary information, which reduces the size of digital files and makes them easier to transmit and store. This process is used extensively in computer applications, such as streaming audio or visual content over the Internet. In the context of acoustics, compression is an increase in density and pressure in a medium, such as air, caused by the passage of a sound wave. 10 Compressor A compressor controls the dynamic range of a signal by reducing the part of the signal that exceeds the user-adjustable threshold. When the signal exceeds the threshold, the overall amplitude is reduced by a user-defined ratio, thus reducing the overall dynamic range. Compressor Ratio The compression ratio of an audio compressor determines how much the volume reduces depending on how far above the threshold the signal is. Compressor Threshold The compressor threshold sets the point at which the automatic volume reduction kicks in. When the input goes above the threshold, an audio compressor automatically reduces the volume to keep the signal from getting too loud. - 31 - Computer-Aided Design (CAD) Computer-aided design (CAD) is software used to create digital models or drawings. These models can be in the form of 2-D multiview drawings or as 3-D models, which are used for a wide variety of purposes. In the AV industry, CAD is used in the creation of AV system design documentation, such as in the case of architectural floor plans or detail drawings. 11 Computer-Video Interfaces A computer-video interface enables a client to connect a computer display output to the display system. Condenser Microphone A condenser microphone transduces sound into electricity using electrostatic principles. Conductor A conductor is a material that easily conducts an electric current because some electrons in the material are free to move. Conduit Conduit can mean any pathway, but in the AV and electrical industry it is a circular tube that houses cable. Cone Cone is the most commonly used component in a loudspeaker system. It's found in all ranges of drivers. Conference and Meeting Room A conference and meeting room is like a boardroom, which is intended for groups of various sizes to participate in interactive discussions for long periods. - 32 - Conferencing System A conferencing system uses technology that enables people separated by distance come together to share information. Conferencing systems may include projection, monitor displays, computers, satellite connections video and audio playback devices, and much more. Connector A connector is used on equipment to continue the pathway to the electronics. It is terminated onto cables. The type of connector used on a cable must be compatible with the connector type used on the equipment for a reliable connection. Console A console or workstation is used to organize & optimize audiovisual equipment in a central location for a specific purpose such as audio or video editing or production. Constant Voltage 1. Constant voltage (25V, 70V, 100V) is a method of distributing power to loudspeakers over a large area with less loss than a typical connection would provide. This can also be called a "high impedance system." 2. Also called a high-impedance system, this is a method of distribution over a large area with less loss than a typical connection would provide. Contact Closure A contact closure is the simplest form of remote control communication. It is a switch. This type of control point operates a device by opening or closing an electrical current or voltage loop. It has the most basic protocol language: “on” (closed circuit) or “off” (open circuit). Container A container is the structure of a file where the data is stored. It defines how the data is arranged to increase performance and which codecs are used. - 33 - Content Deliverables Content deliverables identify what must be delivered in terms of designs, plans, reports, instructions, training, operating and maintenance manuals. Also known as non-product deliverables. Content Delivery Network (CDN) A Content Delivery Network (CDN) is a distributed network of caching servers that can provide hosted unicast distribution of media for an organization. Continuity Continuity is the quality of being continuous (as in a continuous electrical circuit). Continuity of Operations Plan (COOP) A Continuity of Operations Plan (COOP) is a written document that establishes what services and personnel are critical to continuing the mission of the organization during an emergency. The plan may also detail changes in security and how the organization will continue to operate during the emergency. Contrast Absolute difference in luminance between the peak white and black levels, where white and black luminance is displayed simultaneously. As used in the ANSI/INFOCOMM 3M-2011 Standard, the term contrast is not to be confused with "contrast" controls on a projector. Contrast Contrast is the range of difference between the lightest and darkest areas of the display. - 34 - Contrast Ratio Contrast ratio describes the dynamic video range of a display device as a numeric relationship between the brightest color (typically white) and the darkest color (typically black) that the system is capable of producing. Two methods are used to specify contrast ratio; the full on/full off method describes the dynamic contrast ratio and the ANSI measures the static contrast ratio. Control Script A button-by-button control script is used to define what actions the control system will initiate when a specific function (button) is selected. Control System A control system is a subsystem that enables simplified operation of other complex systems such as an audiovisual and/or lighting systems. Control Track Control track is the portion along a length of a recorded tape on which sync control information is placed; used to control the recording and playback of the signal. Converters Converters are used to convert signals from one format to another such as from analog to digital or from low resolution to high resolution or vice versa. 3D converters convert images or video from two dimensional to three dimensional viewing. Coverage Pattern A coverage pattern is the predictable pattern of sound energy that every loudspeaker emits. The coverage pattern is based on the frequency of the sounds and the physical size of the loudspeaker. - 35 - Crash Switcher A crash switcher creates mechanical connections of the cables or circuit, like an on/off light switch. This type of switching creates a visible "glitch" in the video program. Critical Distance Critical distance (D c ) is the point where sound pressure level of the direct reverberant sound field are equal. Crossover A crossover is used to separate the audio signal into different frequency groupings and route the appropriate material to the loudspeaker or amplifier in order to ensure that the individual loudspeaker components receive program signals that are within their optimal frequency range. There are two types of crossovers: passive and active. Crosstalk Crosstalk is any phenomenon by which a signal transmitted on one circuit or channel of a transmission system creates an undesired effect in another circuit or channel. Critical path schedule The critical path schedule reveals the interdependence of activities and assesses resource and time requirements and trade offs. It also determines the project’s completion date and provides the capability to evaluate activity performance. Cue Systems Cue systems help the speaker communicate with the projectionist and vice versa during a presentation, but with today's presentation systems, the presenter can often control the projector & slides remotely. - 36 - Current Current is the rate of electrons flowing through a circuit per second. Current is measured in amperes. It is typically represented in math by "I" for "intensity" or "A" for "amperes." Curvature of Field A blurry appearance around the edge of an otherwise in-focus object (or the reverse) when the velocity of light going through the lens is different at the edges than at the center of the surface. Curvature of field can be caused by the flat sensors in digital cameras or by the lens design. D D-Sub Connector D-sub connector is a generic name for D-shaped serial connectors used in data communications. Dante DanteTM is a proprietary digital audio Network Layer protocol designed by Audinate. Dante sends audio information as Internet Protocol (IP) packets. It is fully routable over IP networks using standard Ethernet switches, routers, and other components. Dante traffic requires no separate infrastructure; it can coexist with other data traffic. Dante controller software manages data prioritization and audio routes. Dashboard A visual display for administration and monitoring of AV systems' power consumption. Data Interface A data interface is a method of retrieving information from the Cloud and passing it into the AV system within a space. - 37 - Day Parting Day Parting is the process of splitting a day of scheduled content into smaller time segments to reach specific audiences at specific times of day. DB SPL DB SPL is a measure of sound pressure level measured in dynes per centimeter squared. 0 dBSPL equals 0.0002 dynes/cm2. dB SPL is used as a measure of acoustical sound pressure levels, and is a 20log function. Dealer A dealer is a company that sells products that are manufactured by other companies directly to end users. Some manufacturers restrict their sales to a few authorized dealers. Decibel Decibel (dB) describes a base-ten logarithmic relationship of a power ratio between two numbers. A decibel uses a logarithmic scale to describe ratios with a very large range of values that can vary over several orders of magnitude. A decibel is also used for quantifying differences in voltage, distance, and sound pressure as they relate to power. Decoding In the context of video signals, decoding is the process in which a compressed or encoded signal is expanded into its components parts, including red, green, blue, horizontal sync, and vertical sync. Dedicated Ground (Ambiguous term to be avoided). Dedicated Power (Ambiguous term to be avoided). - 38 - Default Gateway The default gateway is a router on a TCP/IP network that serves as an access point to another network. It is used to send traffic out from a network when the destination IP address on a packet does not match any routes in the routing table. Deflection Coil Deflection coil is a uniform winding of wire used to electromagnetically direct an electron beam to draw an image on a cathode ray tube (CRT). Delay Delay is the retardation of a signal. In the context of audio processing, it is an adjustment of the time in which a signal is sent to a destination, often used to compensate for the distance between loudspeakers or the differential in processing required between multiple signals. If the delay is an unintended byproduct of signal processing, it is usually referred to as latency. Delivery Delivery is an administrative office that transports products to and from customer sites. Demodulator Demodulator is an electronic device that removes information from a modulated signal. Depth of Field Depth of field is the area in front of a camera lens that is in focus from the closest item to the camera to the farthest. Design Team Designs the buildings and systems. Architect, AV Designer, Interior Designer, Consultants (Electrical, Mechanical, Plumbing, Structural, Lighting, Data/Telecom, Life Safety, Acoustical, Security, etc.) - 39 - Detail Drawing A detail drawing enlarges small items to show how they must be installed. They depict items too small to see at the project's typical drawing scale. Device Management System (DMS) A device management system (DMS) is a network server that manages a particular type of device or devices by collecting status information and alarms. Dial Plan A dial plan is a set of configurations that instructs a gatekeeper or other call processing agent on how to route calls. Dielectric Constant Dielectric constant describes the ability of a material between two conductors to store an electrical charge. Dielectric strength is determined by the material’s type and thickness, and is the amount of voltage that insulation can stand before it breaks down. Differential-Mode Differential-mode refers to either noise or surge voltage disturbances occurring between the power hot and the neutral conductor. Most differential mode disturbances result from load switching within a building, with motor type loads being the biggest contributor. Differentiated Service Differentiated Service, also known as DiffServ, is a Network-Based Quality of Service (NQoS) strategy wherein data from specific applications or protocols are assigned a class of service. Flows assigned a high priority are given preferential treatment at the router, but delivery is not guaranteed. - 40 - Diffusion Diffusion is the scattering or random redistribution of a sound wave from a surface. It occurs when surfaces are at least as long as the sound wavelengths, but not more than four times as long. Diffusion Screen Material Diffusion screen material is rigid acrylic, glass, or a vinyl fabric, that is used as a surface in rear screen projection. This material provides a diffused, coated, or frosted surface on which the image is focused. The ambient light rejection of this material is moderate and is based on the viewer-side material's reflectivity or sheen. See also Screen Gain. Digital Digital is a method of storing or transmitting information by discrete, non-continuous impulses. Digital-to-Analog Converter Digital-to-analog converter is an electronic device that converts digital signals into analog form. Digital asset management system Digital asset management systems are comprised of hardware systems & software that support capture, storage, retrieval & distribution of media assets. Digital assets include everything from digital text & images to audio, video & animations. Digital Direct Drive Image Light Amplification (D-ILA) Is short for Digital Direct Drive Image Light Amplification projectors. - 41 - Digital Light Processing (DLP) DLP is short for Digital Light Processing(TM) by Texas Instruments. It is a projection system that has technology based on the Digital Micromirror Device (DMD). It uses thousands of microscopic mirrors on a chip focused through an optical system to display images on screen. Digital media player Digital media players are devices that allow users to playback or stream audio & video content from digital media servers, the Internet or computer hard drives. Digital Ramp Digital ramp is another form of control signal It is used with A-D and D-A (analog-to-digital and digital-to-analog conversion), volume control, and projector lenses. Digital Out of Home (DOOH) A Digital Out-Of-Home network is a digital signage network with many display screens located in high visibility areas that are operated and controlled remotely from a central network center. It also known as a place-based or location-based network. These networks are used for advertising and informational messaging. Examples include billboards on highways, wayfinding displays in transit areas, and menu boards in food courts. Digital Signage Digital signage is a way of communicating a customized message through the use of strategically located displays. Digital signage systems tend to use data networks with content delivered by servers. The content can be managed and organized from local or remote locations. Digital Signage Media Player A hardware device used to schedule and play digital signage content on displays via digital and analog connections, and over Ethernet networks. - 42 - Digital Signal Processor (DSP) A Digital Signal Processor (DSP) combines processor functions like mixers, limiters, and equalizers into a single piece of equipment. Digital Signage Template Digital signage templates are customizable layouts used for standardizing content on digital screens. They are often broken into zones for updating content within specific regions of a sign. Digital Signal A digital signal is a series of fluctuating "on" and "off" states. Digital Television (DTV) The digital transmission of audio and video television signals. Digital Video Disc or Digital Versatile Disk (DVD) A DVD, or Digital Video Disc / Digital Versatile Disk, is an optical storage medium for data or video. Digital Visual Interface (DVI) Digital Visual Interface is a connection method from a source (typically a computer) and a display device that can allow for direct digital transfer of data. The connection is limited to a distance of 5 meters for resolutions up to 1920x1200. Lower resolutions such as 1280x1024 can reach up to 15 meters. Dimmer A device used to control the intensity of light emitted by a luminaire by controlling the voltage or current available to it. 12 - 43 - Deutsche Industrie-Norm connector (DIN) A Deutsche Industrie-Norm (DIN) is a connector that follows the German standard for electronic connections. Direct Connection In a direct connection, the video source (DVD, live video feed, tuner, etc.) connects to a video displays input (a monitor, projector, or recording device). Direct Couple A direct coupled system is a loudspeaker system in which the amplifier is connected directly to the voice coil wires of the loudspeaker. If multiple loudspeakers are installed onto one power amplifier channel, they are wired in series, parallel, or a combination of series and parallel. This is done to make sure that the impedance of the loudspeaker circuit is at least the minimum rated impedance load of the power amplifier. Direct Current (DC) Direct current (DC) is the type of current that travels in one direction only. Direct Sound Direct sound is also known as near-field, it is sound that is not colored by room reflections. Direct View Display A direct view display houses the light producing elements and screen in one piece of equipment. Directivity Directivity, or Q, is the specific coverage pattern that designers must consider when determining the placement of loudspeakers required to provide full coverage for all of the listeners within a space. - 44 - Dirty Ground (Ambiguous term to be avoided). Disaster Recovery Plan (DRP) A Disaster Recovery Plan (DRP) is a written procedure explaining what to do after a catastrophic disaster results in the total destruction of original equipment and data. DISCONNECTED See System State. Discretionary Access Control (DAC) Discretionary Access Control (DAC) is a form of network access control wherein the system owner determines who can access what resources. Dispersion Dispersion can be seen when a white light beam passes through a triangular prism. The different wavelengths of light refract at different angles, dispersing the light into its individual components. Distributed Scheme A distributed scheme uses a distribution amplifier (DA) to route the signal to multiple devices simultaneously while maintaining signal quality. DAs may have as few as 2 or more than 12 outputs. Distributed System Distributed loudspeaker systems are suspended overhead, often in the ceiling, at regular intervals. Due to their even placement, they can provide even coverage throughout the listening area. - 45 - Distributed Sound Distributed sound is a sound system in multiple loudspeakers separated by distance and typically operates in a lower sound pressure level than a high pressure system. The loudspeakers are most often suspended over the heads of the listeners. Distribution Amplifier (DA) Distribution amplifier is an active device used to split one input into multiple outputs, while keeping each output isolated, and the signal level constant. Distributor A distributor acts as a sales force for manufacturers. Diversity Receiver A diversity receiver is an RF receiver that uses a pair of antennas to receive a transmitted RF signal. Diversity receivers constantly calculate phase differences between signals to dynamically shift between the two antennas and avoid cancellation. Divisible Rooms Divisible rooms, often called "zones," refer to a large area or room that can be sectioned off for concurrent adjacent use by different events. Dock Lifts Also known as dock levelers, these devices are installed in the dock and are used to raise or lower the dock to match the height of the truck. Dock Plates Dock plates typically are metal slabs with handles and are laid over the gap between the truck floor and the loading dock. Dock plates are designed with weight limits. - 46 - Document Camera A document camera is an imaging device used to create a video image of printed documents or three-dimensional objects. Domain Name System (DNS) A domain name system (DNS) is a hierarchical, distributed database that maps names to data such as IP addresses. A DNS server keeps track of all the equipment on the network and matches the equipment names so they can easily be located on the network or integrated into control and monitoring systems. The goal of the domain name system (DNS) is to translate, or resolve, a name into a specific IP address. DNS relies on universal resolvability in order to work: Every name in a DNS must be unique so that information sent to a domain name arrives only at its intended destination. Dome 1. A type of loudspeaker driver construction. Fabric or woven materials are used to create a dome-shaped diaphragm, and the coil is attached to the edge of the diaphragm. 2. A concave surface used in video projection. Doubler, Quadrupler, or Scaler Doublers, quadruplers, or scalers convert bandwidth limited video signals, such as composite or S-Video into a signal format that can be displayed on a device that utilizes only full bandwidth video signals, such as RGBHV. Downstream Downstream refers to devices that are toward the sink of the HDCP signal. For example, a projector would be downstream from the DVD player. Driver In audio a driver is an individual loudspeaker unit. - 47 - Dry Closure Dry closures refer to a circuit that is formed when the two contacts of an open circuit are closed. This type of circuit is either open or closed. Dual Tone Multi Frequency (DTMF) Dual Tone Multi Frequency (DTMF) is the communication format used by standard telephonebased devices. DTMF is used by dialers, access controls, and home automation systems. Dual Channel In a measurement scenario, dual channel is used to indicate that two inputs are used for measuring something under test. The two channels used are a test reference signal and a measured signal. The test or reference signal can be internally or externally generated from the testing device. Inside the testing device, the measured signal will be compared against the reference signal and resultant output will be displayed. The resultant output could be many different displays such as; sum, difference, coherence, and other sophisticated mathematical algorithms. The result could be a number or series of numbers or a representative graph. Ducker A ducker is an audio compression circuit specifically designed to reduce the gain of a primary signal. It is triggered by a specified secondary signal. As an example, a public address system might reduce the volume of background music when a voiceover microphone is activated. Ducts Ducts can mean any pathway. For example, in the AV and electrical industry they can refer to rectangular tubes that house cable or HVAC ducts that carry air. - 48 - Duration Duration is "How Long" and is the combination of: Effort (number of work periods). Resource availability (other projects, operations, etc.). Number of resources (1 or 20 - more not always better). Personal / organizational calendars (weekends, holidays, etc.). DVI-D DVI-D is one of two common multi-pin connectors available for DVI signals. The DVI-D only carries digital video information. See connectors pictured below. DVI-D Male DVI-D Female DVI-I DVI-I is one of two common multi-pin connectors available for DVI signals. The DVI-I carries both analog and digital video to the connection. The DVI-I (interlaced) appearance is similar to the DVI-D Connector, but has a few more pins and allows an analog signal to be transmitted. DVI-I Male DVI-I Female - 49 - Dwell Time The amount of time a display maintains the attention of an audience. Dynamic Host Configuration Protocol (DHCP) Dynamic Host Configuration Protocol (DHCP) is an IP addressing scheme that allows network administrators to automate address assignment. When a device connects to the network, and the device has the “obtain IP address automatically” option activated, the DHCP service or server will take the MAC address of the device and assign an IP address to the MAC address that is unique within the domain address space supported by the DHCP service. The pool of available IP addresses is based on the subnet size and the number of addresses that have been allocated already. Addresses are leased for a preset amount of time. After the lease time has expired, the address may be assigned to another device. The network administrator sets the amount of the lease time. See also Reserve DHCP. Dynamic IP Address A dynamic IP address is a non-permanent address assigned to a network device automatically upon connection to the network. Dynamic Microphone A dynamic microphone is a pressure-sensitive microphone of moving coil design that transduces sound into electricity using electromagnetic principles. Dynamics Processor A dynamics processor is a device that adjusts the gain of an entire signal in response to preset parameters (i.e., they do not adjust only some frequencies). They may have several functions built into one device (limiter, compressor, expander, gate, etc.). Dynamic Range Dynamic range is the difference between the loudest and quietest levels of an audio signal. - 50 - E E.164 E.164 is the International Telecommunication Union (ITU) recommended scheme for numbering public telecommunication systems. It provides a universal dialing scheme. This is the numbering scheme that defines the format for telephone numbers. Early Reflected Sound Early reflected sound is created by sound waves which are reflected (bounced) off surfaces between the source and the listener. The sound waves arrive at the listener's ear closely on the heels of the direct sound wave. Earset Earsets allows the user to listen to an audio signal in a single ear as opposed to both ears in a headset. EBY Connector EBY connectors are commonly found on Kodiak Ektagraphic slide projectors and remote controls. Echo An echo is a reflected version of sound energy acoustically, or duplicated version of a signal electronically, that arrives to the listener with sufficient delay and separation from the original signal to allow the delayed signal to be perceived distinctly and later in time from the original signal. - 51 - Echo Cancellation Echo cancellation is a means of eliminating echo from an audio path. Efficacy The luminous efficiency of a light source expressed as lumen output per watt of power. 13 Effort Effort is "How Much" time it will take to complete a task in its entirety. This is often arrived at through perfect world or best-case estimating using the best resources with everything needed in place-an optimistic practice that usually increases the risk to the project and often leads to underbidding the labor component of the installation. Electronics Industries Alliance (EIA) EIA stands for Electronics Industries Alliance. This association determined recommended audio and video standards in the United States until 2011. Electret Microphone An electret microphone is a type of condenser microphone. It has prepolarized material, called "electret," which is applied to the microphone’s diaphragm or backplate. This provides a permanent, fixed charge for one side of the capacitor configuration. This permanent charge eliminates the need for the higher voltage required for powering the typical condenser microphone, so it can be powered using small batteries and normal phantom power. Electrical Service Electrical service refers to the conductors and equipment for delivering energy from the electricity supply system to the wiring system of the site served. - 52 - Electromagnetic Induction Electromagnetic induction is a process that transfers a current from an input to an output coil. This means that the current from the source, flowing through the first coil, creates a magnetic field. Elevation Drawing An elevation drawing is a two-dimensional view of a single surface. It is commonly used for creating a true picture of what a surface will look like. Electromagnetic interference (EMI) Electromagnetic interference (EMI) is the improper operation of a circuit (noise) due to the effects of interference from electric and/or magnetic fields. Electrical Nonmetallic Tubing (ENT) Electrical nonmetallic tubing (ENT) is an easily bendable PVC tube. It can be bent by hand, and pushed through walls and floors. Electrical Metallic Tubing (EMT) Electrical metallic tubing (EMT) is the most popular type of metal conduit you will come across. It is appropriately called "thinwall" because the tube is not very thick. Emissive Technology Emissive Technology is any display device that emits light to create an image. Encoded An encoded signal is one that has been compressed into another form to reduce size or complexity. - 53 - Encoding Encoding is the process of combining the signals to reduce the number of conductors. This is accomplished with electronic circuits, and results in "bandwidth limiting." Encryption Encryption is the process of transferring data into an unreadable format for transmission or storage. Encrypted data must be decrypted by the data recipient. End User An end user is a person or group of persons designated to operate the AV system. Energy Management Plan (EMP) A document that details a systematic approach to implementing the most effective power consumption methods and procedures to achieve and maintain optimum energy usage. ENG Camera ENG is an acronym for Electronic News Gathering typically for broadcasting. ENG cameras are used for shoots with lone reporters in the field, TV crews, production trucks and remote newscasts. Enterprise (AV) An enterprise is an end user environment consisting of 10 or more standardized AV spaces. Environmental Sustainability Environmental sustainability is the effort to create and maintain conditions under which humans and nature can exist in productive harmony, and fulfill the social, economic, and other requirements of current and future generations. - 54 - Equalizer An equalizer is a piece of electronic equipment that adjusts or corrects the frequency characteristics of a signal. Equipment Grounding Equipment grounding is the connection to ground (earth) or to a conductive body that extends that ground (earth) connection, of all normally non-current-carrying conductive materials enclosing electrical conductors or equipment, or forming part of such equipment. The purpose is to limit any voltage potential between the equipment and earth. In some jurisdictions the official term, as defined by code, is "earthing" rather than "grounding." Equipment Grounding Conductor (EGC) Equipment grounding conductor (ECG) is the conductive path installed to connect normally non-current-carrying metal parts of equipment together and to the system grounded conductor or to the grounding electrode conductor, or both. 14 Equipment Rack An equipment rack is a centralized housing unit that protects and organizes electronic equipment. Equivalent Acoustic Distance (EAD) EAD, or Equivalent Acoustic Distance, is the farthest distance one can go from the source without the need for sound amplification or reinforcement to maintain good speech intelligibility. It is a design parameter dependent on the level of the presenter and the noise level in the room. - 55 - Ergonomics Ergonomics, also known as Human Factors or Human Factors Engineering, is the scientific study of the way people interact with a system. It focuses on effectiveness, efficiency, reducing errors, increasing productivity, improving safety, reducing fatigue and stress, increasing comfort, increasing user acceptance, increasing job satisfaction, and improving quality of life. Ergonomics is different than a time and motion study, which focuses solely on productivity and efficiency. Ethernet Ethernet is a set of network cabling and network access protocol standards administered by the 802.3 subcommittee of the IEEE. Ethernet transmits data over local area networks at 10 Mbps, 100 Mbps, 1 Gbps, or 40/100 Gbps. Ethernet signals are transmitted serially, one bit at a time, over the shared signal channel. EtherSound EtherSound is a proprietary digital audio Data Link Layer protocol designed by Digigram. It uses standard 100 Mbps or 1 Gbps Ethernet cabling, switches, and other components. It requires a separate network with dedicated bandwidth. EtherSound signals are non-routable. Evacuation Cooling Evacuation cooling creates a vacuum within the rack using fans to draw air out of the rack, usually through the top vents. Expander Expander is an audio processor that comes in two types- a downward expander and a part of a compander. - 56 - EDID (Extended Display Identification Data) Extended Display Identification Data (EDID) is a data structure within a sink that is used to describe the sink's capabilities to a source. These capabilities include native resolution, color space information, and audio type (mono or stereo). External Configuration External configuration refers to the ability of one device to configure other devices and subsystems. F F Connector An F connector is a terminating connector used on coaxial solid-core cables such as RG-6u and RG-59u, typically with passband modulated signals such as cable, terrestrial, and satellite television. F-Stop F-stop is the ratio of focal length to the effective diameter of a lens; also called f-number, it represents how much light is able to pass through the lens. Far Field Far field is the sound field distant enough from the sound source so the SPL decreases by 6 dB for each doubling of the distance from the source (inverse square law). 15 Farthest Viewer Viewer positioned at the farthest distance from the screen as defined by the viewing area. - 57 - Fast Fourier Transform (FFT) The Fourier Transform is a mathematical filtering process that determines the spectral content of a time domain signal. The Fast Fourier Transform, or FFT, is a computationally efficient version of the same. 16 Feedback In the context of audio, feedback is unwanted noise caused by the loop of an audio system's output back to its input. In the context of control systems, feedback is data supplied to give an indication of status, i.e., on or off. A CPU sends out an instruction to a device, which executes the instruction and then replies back to the CPU. Feedback Stability Margin (FSM) The feedback stability margin is extra margin, added into the NAG formula, that represents extra gain that a sound system may need. It is the possibility of feedback due to the nonlinearity across the frequency band of a sound system. If the system has not been equalized, the FSM must include a 12 dB deficit to your calculation. If the system has been equalized, then a 6 dB deficit will need to be included. Fiber Optic Fiber optic technology uses glass or plastic threads or wires to transmit information. Field Field is one half of a video frame containing every other line of information. Each standard video frame contains two interlaced fields. File Server A file server is computer responsible for storage and management of data in a central location, so that other computers on the same network can access and share the same files. - 58 - Filter A filter removes or passes certain frequencies from a signal. Firewall A firewall is any technology, hardware, or software, that protects a network by preventing intrusion by unauthorized users and/or regulating traffic permitted to enter or exit the network. A firewall controls what traffic may pass through a router connecting one network to another. Firewalls control access across any network boundaries, including between an enterprise network and the Internet, or between LANs within an enterprise. Firmware Firmware is a type of software that has been permanently stored in a piece of hardware. Fixed Matrix Fixed matrix is display type composed of discreet rows of individual light emitting elements, such as pixels, which recreate an image. Fixed matrix displays replaced cathod-ray tube (CRT) displays, which employed a "scanning" display method. Fixture A fixture is a lamp housing that is mounted or fixed in place. Flex Life Flex life is the number of times a cable can be bent before it breaks. A wire with more strands, or more twists per inch, will have a greater flex life than one with a lower number of strands, or one with less twists per inch. Flexible Metal Conduit Flexible metal conduit, called flex for short, is typically connected to a movable piece of equipment. - 59 - Flow Chart A flow chart is a graphical representation of an algorithm. Fluorescent Light Fluorescent lights are very energy efficient bulb types that create a widely dispersed illumination within a room. These lights have a color temperature around 2,700 to 6,500 K. Focal Length Focal length, abbreviated "FL," is the distance, in millimeters, between the center of a lens and the point where the image comes into focus. The shorter the focal length, the wider the angle of the image will be. Use cursive F when stating FL: Focus Focus is the act of adjusting a lens to make the image appear clear, sharp, and well-defined. Font A font is a set of written letters, numbers, and symbols that share a similar size, weight, and style. Foot-Candle Footcandle, abbreviated "fc," is an English unit of measurement expressing the intensity of light illuminating an object. The illumination from one candle falling on a surface of 1 square foot at a distance of 1 foot. - 60 - Footlambert The footlambert (fl) is a U.S. customary unit of measurement for luminance. It is equal to 1/pi candela per square foot. Footprint A footprint indicates where possible mounting points are to join two pieces together, the total contact area, and how they may or may not fit together. Footprint is also the space required to house an equipment rack or device. Footprint is the coverage area of a communications satellite. Fork Lifts Fork lifts are used to bring palletized loads from the truck to ground level. To prevent damage to equipment cases the loads should be secured to pallets before being loaded into the truck. Frame Frame is an individual segment of film. Film is a complete video picture or image of odd and even fields; two fields equal one frame. Frame Rate Frame rate is the number of frames sent from a display source per second. Frequency Frequency is the number of complete cycles in a specified period of time. Formerly expressed as cycles-per-second (cps), now specified as Hertz (Hz). Frequency Domain The Frequency Domain views a signal as amplitude versus frequency. In other words, you can view the amount of energy at different frequencies. The energy can be divided into octaves or more often, in fractions of octaves. It allows you to view a signal's spectral energy. - 61 - Frequency Response Frequency response is a shortened way of expressing a device's amplitude response versus frequency characteristic. A frequency response is usually presented as a graph or plot of a device's output on the vertical axis versus the frequency on the horizontal axis. 17 Fresnel Lens Fresnel lens is a flat glass or acrylic lens in which the curvature of a normal lens surface has been collapsed in such a way that concentric circles are impressed on the lens surface; often used for the condenser lens in overhead projectors, in rear projection screens, and in studio spot lights. Front Screen Projection Front screen projection is a system that employs a light reflecting screen for use when the image will be projected from a source in front of the screen. Full Bandwidth Signal Full Bandwidth Signal is the highest quality analog video signal. This is because each signal l - R, G, B, H, and V - has its own cable. Full Bandwidth Signal is also known as an "unencoded signal." Full Duplex Full duplex communication is a form of bidirectional data transmission in which multiple messages may travel on the same medium simultaneously. Full HD Full HD is an HDTV high-definition video mode characterized by 1080 horizontal lines of vertical resolution and progressive scanning. It is commonly notated as 1080p. - 62 - Full On/Off Contrast Also known as "Sequential Contrast Ratio." The difference in intensity between the "FULL ON" and "FULL OFF" intensities of the display device. Contrast is measured in two separate tests. This version of contrast is not used in the ANSI/INFOCOMM 3M-2011 Standard. Fully Qualified Domain Name (FQDN) A Fully Qualified Domain Name (FQDN) is a domain name system (DNS) name that specifies the exact location of an object in the DNS hierarchical database. The FQDN must contain at least three levels, including the top-level domain name, preceded by the organizational name, preceded by a service or host name. Function A function is an individual action. For example, if you select “lights on” from a user interface, the lights in the room power on. Functional or Resource Manager Responsible for training, equipping and providing the internal resources (Labor, Materials, Equipment, Facilities) that make up the costs of a project. Typically responsible for Quality Assurance and Resource Utilization. Functions and Features In the context of a needs analysis, the functions and features are the specific capabilities the AV system or equipment must possess in order to perform the required tasks. Fundamental Frequency Fundamental frequency is the lowest frequency in a harmonic series. It is also known as "pure tone." - 63 - G Gain Gain refers to the electronic amplification of a signal. Gain Control A gain control is an electronic adjustment through which the operator can increase or decrease the amplitude of a defined signal element. Gain Sharing Automatic Mixers A gain sharing automatic mixer is an audio mixer that automatically turns up microphone channels that are in use, and turns down microphone channels that are not being used. Gate Gate is an audio processor that allows signals to pass only above a certain setting or threshold. Gated Automatic Mixer A gated automatic mixer is an audio mixer that turns microphone channels either up or all the way down automatically, like an on/off switch. Gateway A gateway is usually the highest router in the hierarchy of routers. It connects a local network to an outside network, and all traffic must travel through it. A gateway will pass traffic to the routers below, and the routers below look to the gateway to find names (DNS addresses) that are not found on the local network. Gauge Gauge is the thickness or diameter of a wire. - 64 - General Notes General notes provide general information related to the electrical components depicted within the electrical plans. Genlock Genlock locks the synchronization signals of multiple devices to a single source. Glass Bead Screen Glass bead screen is a screen covered with tiny glass beads, each of which provides a spherically reflective surface. Good Viewing Area The good viewing area is the best place to view a screen. It is typically defined as any point within 45 degrees to the left or right from on-axis. The total good viewing area is 90 degrees. Graphic Equalizer A graphic equalizer is an equalizer with an interface that resembles a graph comparing amplitude on the vertical with frequency on the horizontal. Graphic equalizers normally come in 2/3 octave, or, more often, 1/3 octave filters sets. Filters are usually set on ISO (International Organization for Standardization) defined center frequencies. Center frequencies and bandwidth are fixed for these filters, so named as the adjustments to the sliders offer a "graphic" representation of the frequency response. Active graphic equalizers can provide boost and cut capability. Graphic Adaptor Graphics adaptors, or "video cards," output computer signals. - 65 - Graphics Card A graphics card controls the coloring, shape, and level of detail of the computer display signal. Grayscale Test Pattern A grayscale test pattern displays the broadest range of intensities between black and white on the screen. Grayscale Grayscale is the brightness and darkness of a color. It is sometimes called "value." It is one of the three attributes of color; the other two are hue and chroma. Ground Ground is the earth. In the context of an electrical circuit, ground is the earth or some conductive body that extends the ground (earth) connection. In the context of electronics, ground is the 0 V (zero volt) circuit reference point. This electronic circuit reference point may or may not have any connection to earth. 18 Grounded Grounded (grounding) is connected to ground or to a conductive body that extends the ground connection. (See also equipment grounding and system grounding.) Grounded Conductor A grounded conductor is a system or circuit conductor that is intentionally grounded. It is commonly called the neutral. 19 - 66 - Ground Fault Ground fault is an unintentional, electrically conducting connection between an ungrounded conductor of an electrical circuit and the normally non-current-carrying conductors, metallic enclosures, metallic raceways, metallic equipment, or earth. Ground fault is the electrical connection between any ungrounded conductors of the electrical system and any noncurrentcarrying metal object. Ground-Fault Circuit Interrupter (GFCI) Ground-fault circuit interrupter is a device intended for the protection of personnel. It deenergizes a circuit or part of a circuit when a current to ground exceeds an established value. A class A ground-fault circuit interrupter trips when the current to ground is 6 mA or higher. The excess current is presumably caused by a ground fault. 20 Ground-Fault Current Path Ground-fault current path is an electrically conductive path from the point of a ground fault on a wiring system through normally non-current-carrying conductors, equipment, or the earth to the electrical supply source. Grounding See Grounded. Grounding Conductor Grounding conductor is a conductor used to connect equipment or the grounded circuit of a wiring system to a grounding electrode or electrodes. Grounding Conductor, Equipment See equipment grounding conductor. - 67 - Ground Lift Ground lift is the interruption of a cable shield connection by means of a switch or simple omission in an attempt to solve a hum or buzz problem from current flowing on a cable shield due to a Pin 1 problem, detrimental ground loop. Ground lift is the interruption of the connection between chassis ground and signal ground usually by means of a switch. Ground lift is an incorrect term used for a 3-pin to 2-pin AC adapter. (See also grounding adapter.) Ground Loop Ground loop is an electrically conductive loop that has two or more ground reference connections. They can be detrimental when the reference connections are at different potentials causing current flow within the loop (IEEE). Ground Plane Ground plane is a continuous conductive area. The fundamental property of a ground plane is that every point on its surface is at the same potential (low impedance) at all frequencies of concern. Ground Potential Ground potential is a point of no potential in a circuit. Ground Reference Ground reference is the 0 V (zero volt) reference point for a circuit. Grounding Adapter Grounding adapter is the correct term for a 3-pin to 2-pin electrical, the design of which is defined by NEC 406.9. The rigid tab or lug is to be used for equipment grounding and not left "floating." - 68 - Grounding Electrode Grounding electrode is a conducting object through which a direct connection to earth is established. 21 Grounding Electrode Conductor Grounding electrode conductor is the conductor used to connect the system grounded conductor or the equipment to a grounding electrode or to a point on the grounding electrode system. Group Management Protocol (GMP) A group management protocol (GMP) allows a host to inform its neighboring routers of its desire to start or stop receiving multicast transmissions. Without a GMP, multicast traffic is broadcast to every client device on the network segment, impeding other network traffic and overtaxing device CPUs. 22 Group of Pictures (GoP) A group of pictures (GoP) is a set of successive frames that are required to display a complete series in a digital AV signal. It includes the visible picture, timing/sync information, and compression frames. Graphical User Interface (GUI) The graphical user interface, or GUI (often pronounced "gooey"), provides a visual representation of the system features and functions. H Handheld Microphone A handheld microphone can be held in the hand or mounted on a lectern or stand for handsfree operation. - 69 - Half-Duplex Half-duplex is a form of data transmission in which only one network node at a time sends data. Note that the International Telecommunication Union (ITU) uses this term to refer to simplex communications. Hardware Hardware is a piece of physical equipment or device. Hardware refers to the actual physical components of an electronic device. Harmonic Distortion Harmonic distortion is a multiple of a fundamental frequency which does not exist in the original signal. Harmonic distortion can occur in both the electronic components as well as loudspeakers, which makes it one of the most common types of distortion. Harmonics Harmonics are higher frequency sound waves that blend with the fundamental frequency. Heating, Ventilation, and Air Conditioning (HVAC) HVAC stands for "Heating, Ventilation, and Air Conditioning," and it refers to the technology associated with environmental comfort. HVAC systems control the temperature of a space, and they remove moisture, odors, smoke, heat, dust, airborne bacteria, or carbon dioxide from a room, while replenishing oxygen. 23 Hertz (Hz) Hertz (Hz) indicates cycles per second of an electrical signal. - 70 - HD-15 (15-pin VGA) Connector HD-15 (15-pin VGA) connector is a video connector that is typically associated with the output of a computer graphics card. It is often called a “VGA” connector. It has three rows of five pins, which carry analog red, green, blue, and sync signals along with display data channel information (see DDC). Female Male HDCP Key An HDCP Key is a long number that a program uses to verify authenticity and encode/decode content. HDCP processes use multiple types of keys. These keys are strongly protected by Digital Content Protection, LLC. HDCP Receiver HDCP Receiver is a device that can receive and decode the HDCP signals. A television is an example of a receiver. HDCP Repeater An HDCP repeater is a device that can receive HDCP signals and transmit them to another device, such as a switcher or distribution amplifier. - 71 - HDCP Sink An HDCP Sink is a device that receives and decodes the HDCP signals. HDCP Source An HDCP Source is a device that sends HDCP encoded signals and content. HDCP Transmitter HDCP Transmitter is a device that can send HDCP encoded signals and content. A Blu-ray player is an example of an HDCP Transmitter. Headend Headend is the equipment located at the start of a cable distribution system where the signals are processed and combined prior to distribution. Headroom Headroom is the difference in dB SPL between peak and average level performance of an audio system. For a speech application, the recommended value is 10 dB, and for program audio, the recommended value is 20 dB. 24 Heat Load Heat load is the heat that is generated and released by a piece of electronic equipment. It is measured in British Thermal Units. Heat Sink Heat sink is a device that absorbs and dissipates heat produced by an electrical component. - 72 - Hemispheric Polar Pattern Hemispheric polar pattern is the dome shape of the region that some microphones will be most sensitive to sound. Used for boundary microphones. High-Bandwidth Digital Content Protection (HDCP) High-Bandwidth Digital Content Protection (HDCP) is a form of digital rights management developed by Intel to control digital audio and video content as it travels across DVI or HDMI connections. It prevents transmission or interception of non-encrypted HD content. HDCP support is essential for the playback of protected HD content. Without the proper HDCP license, the material will not play. It is difficult but possible to distribute to multiple DVI or HDMI outputs; all the equipment used to distribute the material must be licensed. This is part of blanket negotiations between device manufacturers and film and media companies. High Definition Multimedia Interface (HDMI) HDMI, or High Definition Multimedia Interface, is a point-to-point connection between video devices, and it is the standard for high quality all-digital video and audio. HDMI signals include audio, control, and digital asset rights management information. It is a "plug-and-play" standard that is fully compatible with DVI. High Definition Television (HDTV) HDTV is the abbreviation for High Definition Television. High Pass Filter A high pass filter is a circuit that allows signals above a specified frequency to pass unaltered while simultaneously attenuating frequencies below the specified limit. Hiss Hiss is a broadband higher frequency noise typically associated with poor audio system gain structure. - 73 - Horizontal Blanking Horizontal blanking is the H sync pulse that tells the retrace electron beam to turn off at the end of each line. Horizontal blanking is only used in CRT technologies. In CRT displays, horizontal blanking interval is the time during which the electron beam is turned off so that it can move into position to begin the next scan line; usually a very brief period, lasting 5 -15 microseconds. Horizontal Blanking Interval Horizontal blanking interval is the time during which the electron beam is turned off so that it can move into position to begin the next scan line; usually a very brief period, lasting 5-15 microseconds. Horizontal Scan Rate The horizontal scan rate, also known as horizontal scanning frequency, is the number of horizontal lines a raster display device draws each second. It is measured in kilohertz (kHz) and is associated with analog display technology. Horns Horns are loudspeakers that reproduce mid to high frequencies. Host A host is a computer or other device that is connected to a network. Hot Plug Hot plug is a low-level signal sent by a source that indicates whether or not a sink or display is connected. 25 - 74 - Hot Spot A hot spot is the part of a displayed image that is unevenly illuminated, usually appearing as a bright area in the center. Hub A hub is a network device that connects multiple devices together on one shared network segment. Hub and Spoke Topology A hub and spoke wide area network (WAN) topology locates shared network resources on a local area network (LAN) in a central location, the hub. Smaller LANs, such as branch offices or remote workers, connect to the hub via a leased line, virtual private network, or other secure, managed means. Hue Hue is the attribute of a color that represents a red, a purple, a green, etc. It is one of the three attributes that define color; the other two are grayscale and chroma. Hum A hum is an undesirable 60 Hz noise emanating from a sound system or evidenced by a rolling "hum bar" on a display. Human Machine Interface (HMI) See User Interface. Human Resources Human Resources is an administrative office that handles employee paychecks, insurance, benefits, and taxes. It is also responsible for hiring new employees, promotion, and periodic performance review. Human Resources is is also known as "Pay Roll." - 75 - Hypertext Transfer Protocol (HTTP) Hypertext Transfer Protocol (HTTP) is an application layer protocol used for website communication. HTTP is encapsulated in Transmission Control Protocol (TCP) for reliable two-way communication. Further encapsulation in Internet Protocol (IP) allows HTTP to pass through the Internet. The primary language of HTTP is Hypertext Markup Language (HTML). I ICMP Echo Request ICMP echo request is an administration utility used to test network connectivity and response time. An origin host sends the echo request to a device destination and waits for a response. ICMP echo request is also referred to as PING. Illuminance Light falling on a surface, measured in Lux (lx) or Foot-Candle (ft-c or fc) [1 lux = 0.09 fc]. Not visible to human eye other than in the form of reflected luminance. Image Magnification (IMAG) Image Magnification, or IMAG, is a technique used in live-events to bring the presenter closer to the audience. A camera captures the presenter and routes the image to a large screen. IMAG is usually associated with large-screen projection. Imager An imager is a light-sensitive electronic chip behind a video camera's lens. This device is made up of thousands of sensors, called pixels, which convert the light input into an electrical output. In normal operation, an imager will output a frame of captured video at the frame rate of the video standard. There are two common types of imagers: Charged Coupled Device (CCD) and Complementary Metal Oxide Semiconductor (CMOS). - 76 - Image Resolution Image resolution is the total number of pixels of the display. It is normally expressed as a ratio of horizontal pixels to vertical pixels. Image Size Image size refers to the physical size in terms of width and height of a displayed image. Impact Insulation Class (IIC) Impact insulation class (IIC) is a rating used to quantify impact sound absorption. It is an average of the attenuation in decibels that occurs at frequencies ranging from 100 to 3150 Hz. The higher the IIC rating is, the better insulation from impact noise the material provides. Impedance Impedance is the total opposition to current flow in an AC circuit. Like a DC circuit, an AC circuit contains resistance but it also includes forces that oppose changes in current (inductive reactance) and voltage (capacitive reactance). Impedance takes into account all three of these factors. Impedance is frequency dependent, measured in ohms and is symbolized using the letter "Z." Impedance Matching Impedance matching means having an impedance value on an input that an output is expecting. It does not necessarily mean having comparable impedances on an input and an output. Impedance Meter An impedance meter is used to measure true impedance of an electrical circuit. - 77 - Incandescent Light Incandescent light is produced by heating a wire filament by passing sufficient electric current through it until it reaches a high enough temperature that it glows. These types of lights have a color temperature of about 2,800 K to 3,200 K, resulting in a warmer hue. Independent Group Management Protocol (IGMP) Internet Group Management Protocol (IGMP) is the IPv4 group management protocol. IGMPv1 allowed individual clients to subscribe to a multicast channel. IGMPv2 and IGMPv3 added the ability to unsubscribe from a multicast channel. Independent Sales Representative An independent sales representative is not tied to any one company, but may sell products from several manufacturers. Inductance Inductance is the property of a circuit that opposes any change in current. Induction Induction is the influence exerted by a magnetic or magnetic field upon a conductor. Inductive reactance (XL) Inductive reactance (XL) is in opposition to current flow offered by the inductance of a circuit. It is dependant upon frequency and inductance. Inductor An inductor is a passive electric component that resists changes in electric current. For a given inductance value, expressed in Henrys, the inductor will have a greater opposition to AC current flow at higher frequencies than at lower frequencies. - 78 - Infrared (IR) Infrared (IR) is a range of light frequencies used to send information. IR transmission requires line-of-site between transmitter and receiver. Infrared signals may be either wired or wireless. Inductor Inner duct is also nonmetallic tubing, but stiffer than ENT. It is used inside other conduits, creating multiple paths in the same conduit. Input An input is a connection point that receives information from another piece of equipment. Input Interface The input interface consists of the connections between the control system and the components. These connections can include electrical and mechanical interfaces. Input/Output Port (I/O Port) Typically, an input/output (I/O) port is used for input binary signals to a control system to indicate the state of a connected device, such as active or inactive, on or off, or connected or not-connected. An I/O port is complementary to a dry closure circuit. It is commonly constructed so each input is at a low voltage or neutral level. Inside Sales Inside sales are made when the customer comes to the AV company. Installation Team Provides construction and installation services. General Contractor, AV Integrator, Multiple Sub-Contractors (Electrical, Mechanical, Plumbing, Structural, Lighting, Data/Telecom, Life Safety, Acoustical, Security, etc.). - 79 - Institute of Electrical and Electronics Engineers (IEEE) IEEE is an abbreviation for The Institute of Electrical and Electronics Engineers. Insulation Insulation is a material applied to a conductor that is used to isolate the flow of electric current between conductors and to provide protection to the conductor. It is also known as dielectric. Intelligibility Intelligibility is an evaluation of a sound system's ability to produce a meaningful reproduction of sound. An intelligible sound reinforcement system can reproduce the vowels and consonants of a sound source accurately, which allows listeners to identify words and sentence structure. This gives sound meaning. 26 Interactive whiteboard Interactive Whiteboards are an essential tool in business and classroom communications. They are used to display text, data, and graphics from a computer or projector onto a large surface or display. Presenters and users can then interact with the image using a pen, stylus, finger, or other device. Intercom An intercom is a sound system that is used for inter-communication between people or rooms. It provides two-way communication where all participants can listen and talk at the same time. Interlaced Scanning Interlaced scanning is the scanning process that combines odd and even lines of pixels in a video image to produce a full frame of video signal. - 80 - Intermediate Metal Conduit (IMC) Intermediate metal conduit (IMC) is heavier than EMT. It has a threaded metal end to join pieces together with couplers. It offers much better physical protection and EMI protection. Internal Configuration Internal configuration refers to the setup and customization of management or control device. International Traffic in Arms Regulations (ITAR) The International Traffic in Arms Regulations (ITAR) restrict the movement of defense-related technology across international borders. This law prohibits particular security technology from being sold from one country to another. As a result, encryption technology cannot be sold internationally. Internet Assigned Names and Numbers (ICANN) Internet Corporation for Assigned Names and Numbers (ICANN) is a nonprofit organization chartered to oversee several Internet-related tasks. ICANN manages Domain Name System (DNS) policy, including the top-level domain space for the Internet. Internet Control Messaging Protocol (ICMP) Internet Control Messaging Protocol (ICMP) is a TCP/IP protocol defined in the IETF standard RFC 792. ICMP sends error messages and carries messages for network diagnostic programs. ICMP falls under the Internet Layer of the TCP/IP protocol stack and the Network Layer of the OSI Model. Internet Protocol (IP) Internet Protocol (IP) is a TCP/IP protocol defined in the IETF standard RFC 791. IP defines rules for addressing, packaging, fragmenting, and routing data sent across an IP network. IP falls under the Internet Layer of the TCP/IP protocol stack and the Network Layer of the OSI Model. - 81 - Internet Protocol Television (IPTV) Internet protocol television (IPTV) is a system that delivers television services over a packetswitched network such as a LAN or the Internet. Institute of Radio Engineers Unit (IRE Unit) IRE unit is an abbreviation of the Institute of Radio Engineers. A unit of measurement used as a reference to quantity video signal levels. Integrated Services Digital Network (ISDN) Integrated Services Digital Network (ISDN) is a communications standard for transmitting voice, video and data over digital phone lines or the traditional telephone network. Common applications of ISDN include telecommuting, Internet access, video conferencing & data networking. IFFT (Inverse Fast Fourier Transform) The Inverse Fast Fourier Transform takes a frequency domain signal as its input and produces a time domain signal. 27 Inverse Square Law The inverse square law states that the physical quantity or strength is inversely proportional to the square of the distance from the source of that physical quantity. This means that as the distance from a point source of energy (light or sound) doubles, the energy will be distributed over four times the area. The resulting energy will be one-fourth the original intensity. - 82 - Isolated Ground (IG) Isolated ground (IG) is an equipment grounding method permitted by the NEC for the reduction of electrical noise (electromagnetic interference) on the grounding circuit. Equipment grounding for isolated receptacles and circuits is accomplished via insulated equipment grounding conductors and run with the circuit conductors. The insulated equipment grounding conductor is usually identified by green jacket with a yellow stripe. This isolation between IG receptacles and circuits and the normal equipment grounding is maintained up to the point of the service entrance (or a separately derived system) where the grounded (neutral) conductor, equipment grounding and isolated equipment grounding conductor are bonded together and to earth ground. Often referred to as "technical ground" within the audiovisual industry. Isolated Grounding Circuit An Isolated grounding circuit allows an equipment enclosure to be isolated from the raceway containing circuits supplying only that equipment by one or more listed nonmetallic raceway fittings. The equipment is grounded via an insulated grounding conductor. (See NEC 250.96 (B) for additional information.) Isolated Receptacle An isolated receptacle is a receptacle in which the grounding terminal is purposely insulated from the receptacle mounting means. Isolated receptacles are identified by a triangle engraved on the face and are available in standard colors. The receptacle and thus the equipment plugged into the receptacle are grounded via an insulated grounding conductor. (See NEC 2008 250.146 (D) for additional information.) Isolated Star Ground InfoComm experts determine that this term is ambiguous. See isolated ground. J Jacket Jacket is the outside covering used to protect wires in a cable and their shielding. - 83 - Junction Box A junction box is a metal or plastic enclosure for enclosing the junction of electrical wires and cables. A junction box can be used as a termination point with a custom connector plate or interface plate. A junction box can also be installed and used as a pull box for longer cable runs. K Keystone Error Keystone error is the trapezoidal distortion of the perpendicular lines of a projected image. It is caused by the difference in projection distance from one side of the image to the other due to non-perpendicular placement of the projector relative to the projection surface. L Lamp A lamp is the bulb or source of light output. Latency Latency is response time of the network. It is expressed as the amount of time in milliseconds between a data packet's transmission from the source application and its presentation to the destination application. Lavalier Microphone Lavalier is a small microphone designed to be worn either around the neck or clipped to apparel. Law of Conservation of Energy The Law of Conservation of Energy says that the total energy cannot be created or destroyed. Energy can be transformed from one form to another, and transferred from one body to another, but the total amount of energy remains constant. - 84 - Layer In digital signage, layers are the order in which the graphics will be displayed on the screen. Layers may be placed in front of or behind one another. Learning lab Learning labs are typically classroom environments where students can receive specialized instruction or skills training. These labs rely on pro-AV equipment such as portable presentation systems, audio & video players, whiteboards, computer workstations, jackboxes, headphones and more. Least Favored Viewer (LFV) Least favored viewer (LFV) is the farthest usable seat from the image and is dependent upon the viewing angle toward the screen, image size, and content being displayed. LED Light LED (Light Emitting Diode) lights are low power lights used as indicator lights, within IR Lamps, or to illuminate signs, walkways or displays. LEDs have a long lamp life (30,00050,000 hours) with well-designed integral LED fixtures reaching 100,000 hours in ideal settings (cool, well-ventilated, etc.). Lenticular A lenticular is a screen surface characterized by silvered or aluminized embossing, designed to reflect maximum light over wide horizontal and narrow vertical angles. Must be held very flat to avoid hot spots. Lift gates Lift gates are hydraulic platforms that are installed to the back of a truck and are used to lower heavy items to the ground. - 85 - Lift mount Lift Mounts are mounted to a wall, the ceiling or a cabinet. They are commonly used with large flat-panel displays & projectors where aesthetics, utility and room space are a concern. Lifts Lifts are designed to raise or lower equipment for easy access and storage as needed. Light Light is a general term that includes the mount for the lamp, and the lamp itself. Lighting Fixture A lighting fixture is an installed lighting instrument. Limiter A limiter is an audio signal processor that functions like a compressor except that signals exceeding the threshold level are reduced at ratios of 10:1 or greater. Limiter Ratio The limiter ratio defines how much the limiter will compress signals that exceed its threshold. The limiter compresses only the portion of the signal that exceeds its threshold, after the signal has already passed through the compressor. Limiter Threshold The limiter threshold defines which portions of the signal the limiter will affect. All decibel levels below or equal to the threshold will pass through the limiter unchanged. All signals above the threshold will be compressed. - 86 - Line Driver Line drivers are used for gain and peaking in order to compensate for signal attenuation created by cable resistance for longer cable runs. Line Level Line level is the strength of an audio signal. Line level is used for all routing and processing between components. Liquid Crystal Display (LCD) A Liquid Crystal Display (LCD) is a video display that uses liquid crystals to produce an image. These devices do not emit light directly. Liquid Crystal on Silicon (LCoS) LCoS (liquid crystal on silicon) is a reflective, fixed-resolution LCD imaging technology. LCoS panels resemble LCD panels in size and function. A liquid crystal layer is applied inside an LCoS panel to a reflective Complementary Metal-Oxide Semiconductor (CMOS) mirror substrate. The LCoS chip has a fixed matrix of pixels, each backed by a mirrored surface. Listed Something is listed when equipment, materials, or services are included in a list published by a Nationally Recognized Testing Laboratory (NRTL), such as Underwriters Laboratory (UL), that is acceptable. 28 Live Microphone System A live microphone system is used to amplify the voice of a presenter, or other sound sources (e.g., musical instruments). - 87 - Local Area Network (LAN) A computer network limited to the immediate area, usually the same building or floor of a building. A LAN connects devices within a small geographical area, such as a building or campus. Local Monitor Local monitor is a device used to monitor the output of a signal from a system or other device in a local vicinity. Load Center Load center is an electrical industry term used to identify a lighting and appliance panelboard designed for use in residential and light commercial applications. Logarithm A logarithm is the exponent of base 10 that equals the value of a number. Logic Network Diagram The Logic Network Diagram is a tool that helps sequence and ultimately schedule the project's activities and milestones. It helps determine if all the activities necessary to complete the program are present. Looping Scheme A looping scheme features electronics with the ability of passing on the video signal to another device. Looping distributes a video signal to multiple devices (usually displays) simultaneously. - 88 - Lossless Compression Lossless compression is a process that retains the original quality of a file after it has been compressed and decompressed. WinZip(R), a popular file compression program, is an example of a program that uses lossless compression. Lossy Compression Lossy compression is a form of compression that gives an approximation of the original data by eliminating redundant or unnecessary information. Loudspeaker Loudspeaker is a transducer that converts electrical energy into acoustical energy. Loudspeaker components are primarily a driver within an enclosure. Loudspeaker Circuit A loudspeaker circuit is a group of wired loudspeakers. Each loudspeaker in the circuit will have an impedance value. Low Pass Filter A low pass filter is a circuit that allows signals below a specified frequency to pass unaltered while simultaneously attenuating frequencies above the specified limit. Low Voltage While low voltage is an ambiguous term, it may mean less than 70 VAC to an audiovisual contractor while an electrician may use the same term to describe circuits less than 600 VAC. The term may also be determined by the authority having jurisdiction (AHJ). - 89 - Low Voltage Light A low voltage light is used as a small spot light to light specific elements within a room. The lamps used within these types of lights are designated as MR-16. These offer high efficiency. Lumen Lumen is a measure of the light quantity emitted from a constant light source across one square meter. Luminaire A luminaire, sometimes called a lighting fixture, is a complete lighting unit consisting of a lamp(s) and ballast(s) (when applicable) together with the parts designed to distribute the light, to position and protect the lamps, and to connect the lamps to the power supply. Luminance Light emitted or reflected from an object, measured in Candelas per square meter (cd/m2, also referred to as a 'nit') or foot-Lambert (fL). [1 nit = 0.292 fL]. Lux Lux is a contraction of the words luminance and flux; 10.7 lux is equal to 1 footcandle. M MAC Address A MAC address is the actual hardware address, or number, of an NIC device. Each device has a globally unique Media Access Control (MAC) address to identify its connection on the network. Macro A macro is a set of functions, activated by one button. - 90 - Management Information Base (MIB File) A Management Information Base (MIB) file is a document that defines all of the objects and traps that a particular device or subsystem offers to an SNMP manager/collector. MIB files are text files, formatted according to the SNMP standard, that define a data interface between managers and devices or subsystems. Management Team Provides management services - represents Owner, Developer, Construction Manager, Building Management Agency, and Move Consultant. Manager of Managers (MoM) A Manager of Managers (MoM) is a Network Management System that can manage both devices and Device Management Systems in a unified user interface that can be accessed directly, or through a web interface, enabling use from remote locations. A Manager of Managers can also be configured to send alert messages to key personnel either through email, SMS, SNMP traps, or other notification protocols. Manufacturer Manufacturers create and produce products. Manufacturer Representative A manufacturer representative is employed directly by a manufacturer and sells only its products. Marketing Marketing is the strategy of interesting your potential customers in what you have to offer. - 91 - Master Antenna Television (MATV) MATV stands for Master Antenna Television system- a television system where broadcast programs are received via a master antenna array and then distributed to users over coaxial cable or fiber optic cable. Matrix Decoder A matrix decoder produces red, green, and blue from Y, R-Y, and B-Y. Matrix Switcher A matrix routing switcher is an electronic device with multiple inputs and outputs. The matrix allows any input to be connected to any one, several, or all of the outputs. Matte White Screen A matte white screen is a projection screen made of magnesium carbonate or a similar substance that provides a perfect diffuser for the redistribution of light. In other words, the light energy striking the screen surface is scattered identically in all directions. Matte White is a reference with a Screen Gain of 1.0 (unity gain) surface. Maximum Transmission Unit (MTU) Maximum transmission unit (MTU) is the size in bytes of the largest frame that can pass over a Data Link Layer connection. Any header information must be included within the MTU. Mechanical Switcher A mechanical switcher mechanically connects cables or circuits. It functions like a wall switch, meaning there is a mechanical connection or disconnection between two conductors. Media Retrieval System Media retrieval system is a system in a facility that allows for remote requests of content to be delivered from a headend location. - 92 - Meshed Topology In a fully meshed wide area network (WAN) topology, every local area network (LAN) connects to every other LAN. Metropolitan Area Network (MAN) A MAN is a communications network that covers a geographic area, such as a suburb or city. Mic Level Mic level is a very low level signal. It is only a few millivolts of electrical energy. Microphone A microphone is a device that transduces acoustic energy, sound, into electrical energy. Microphone Sensitivity Microphone sensitivity is a specification that tells how much electrical energy is derived from a specified sound level input. Middleware Middleware is software that provides services to applications that aren't available from the operating system. In a streaming system, for example, middleware software may perform transcoding, compression, or remote access authentication functions, enabling users to access content from diverse endpoints. - 93 - MIDI controllers MIDI controllers allow users to control electronic devices that send and transmit data using MIDI protocol. Controllers such as keyboards, samplers or synthesizers can then work in synchronization with other MIDI-compatible devices such as musical instruments, VCRs, multi-track recorders, computers, light show controllers and more. Midrange Midrange loudspeakers reproduce midrange frequencies, typically 300 Hz- 8,000 Hz. Milestone A milestone is a significant or key event in the project, usually the completion of a major deliverable or the occurrence of an important event, and can often be associated with payment milestones, and client approvals.They are typically created at the beginning or completion of a number of activities. Millwork Millwork refers to items that are custom cut for the project, such as moldings or trim. Mitigation Mitigation is an action taken to lessen or eliminate the impact of a risk. Mix-Minus System A mix-minus system is a type of speech reinforcement system that allows both meeting presenters and participants to be heard. Each loudspeaker is given a separate subsystem, which mixes the microphone signals, minus the closest microphone. Modulator A modulator converts composite or S-Video signals, along with corresponding audio signals, into modulated signals on a carrier channel. - 94 - Modular Connector A modular connector is one used with 4, 6, or 8 pins. Common modular connectors are RJ-11 and RJ-45. Mono Playback Mono playback is a type of playback that uses a single channel of sound. Monocular Vision Monocular vision refers to the visual field that an individual eye can see. In monocular vision fields, images do not appear sharply, depth perception is lost, and color discrimination is weak. 29 Monophonic A Monophonic uses input from all microphones and relays them from the electronic control system to the loudspeakers using a single path or channel. Mounting Mounting is the practice of suspending or attaching components to the structure of a building. MPEG-2 MPEG-2 refers to Moving Pictures Expert Group, a compression scheme that reduces the number of bits needed to code the video image. Multi-Protocol Label Switching (MPLS) Multi-Protocol Label Switching (MPLS) is a networking protocol that allows any combination of Data Link Layer protocols to be transported over any type of Network Layer. MPLS routes data by examining each packet’s MPLS label without examining packet contents. Implementing MPLS improves interoperability and routing speed. - 95 - Multi-Channel Playback Multi-channel playback, or surround sound, can have five or more channels. Multicast Streaming Multicast streaming is a one-to-many transmission: One server sends out a single stream that can then be accessed by multiple clients. Class D IP addresses are set aside for multicast transmissions. In multicast streaming: 1. A server sends the stream to a designated Class D IP address, called the host address. 2. The clients subscribe to the host address. 3. Routers send the stream to all clients subscribing to the host address. Multicast streams require UDP transport. They can only be sent over LANs or private networks; they cannot be sent over the open Internet. Multimeter A multi-meter is a multipurpose test instrument with a number of different ranges for measuring current, voltage, and resistance. Multiplexing Multiplexing is the process used by the combiner to put together a number of modulated signals. Multipoint Multipoint videoconferencing links many sites to a common gateway service allowing all sites to see, hear, and interact at the same time; requires a bridge or bridging service. Also called continuous presence. - 96 - MULTS MULTS (also called parallels) are simply multiple patch points in a horizontal row. They route or split signals to multiple destinations. Music Reinforcement System A music reinforcement system is a sound reinforcement system that is used to amplify and distribute sound from a live musical performance. Multicast Listener Discovery (MLD) Multicast Listener Discovery (MLD) is the IPv6 group management protocol. Multicast is natively supported by IPv6; any IPv6 router will support MLD. MLDv1 performs roughly the same functions as IGMPv2, and MLDv2 supports roughly the same functions as IGMPv3. N Named Path A named path specifies a unique location of a file in a computer's file system. The name given to a file allows an application to find it's exact location and retrieve it from the computer's directory. Native Resolution The native resolution is the number rows of horizontal and vertical pixels that create the picture. The native resolution describes the actual resolution of the imaging device and not the resolution of the delivery signal. National Television System Committee (NTSC ) The abbreviation for National Television System Committee; the standard for analog video transmission in North America. - 97 - Noise Criteria Rating (NC Rating) Originally developed by Leo Beranek in 1957, NC curves were developed to establish satisfactory conditions for speech intelligibility and general living environments. Measurements are taken at eight center octave frequencies from 63 to 8,000 Hz and plotted against a standardized curve. Near Field Near field is the sound field very close to the sound source, between the source and the far field. Technically, a distance less than one wavelength at the frequency of interest. 30 Nearest Viewer See Closest viewer. National Electrical Code (NEC) The National Electrical Code (NEC) is a set of standards for the installation of electrical wiring and equipment. It is adopted in many regions of the United States and published by the National Fire Prevention Association (NFPA). Need In the context of a needs analysis, a need is the basic communication requirement motivating the creation of a new AV system or space. Needed Acoustic Gain (NAG) NAG (Needed Acoustic Gain) is the gain the sound system requires to achieve an equivalent acoustic level at the farthest listener equal to what the nearest listener would hear without sound reinforcement. - 98 - Needs Analysis A needs analysis, also referred to as the programming phase, consists of identifying the activities that the end users need to perform, and then developing the functional descriptions of the systems that support those needs. Network A network consists of two or more nodes interconnected so that they can share data. Network Address Translation (NAT) Network Address Translation (NAT) is any method of altering IP address information in IP packet headers as the packet traverses a routing device. NAT is a TCP/IP service first defined in the IETF standard RFC 1631. The purpose of NAT is to resolve private IP addresses to public IP addresses and vice versa so that devices with private addresses can send data across the Internet. NAT is typically implemented as part of a firewall strategy. NAT operates at the Internet Layer of the TCP/IP protocol stack and the Network Layer of the OSI Model. See also: PAT (Port Address Translation) Network Analysis Network Analysis is the process of capturing network traffic for the purpose of troubleshooting and benchmarking communication that is traveling across the network, including network anomalies, with various tools and techniques. Network Analyzer A network analyzer is a tool that converts bits and bytes captured from a network into a readable format. - 99 - Network-Based Quality of Service (NQoS) Network-Based Quality of Service (NQoS) is a QoS strategy that involves managing data traffic so that the delivery of important or time-sensitive traffic is prioritized over other network traffic. Network Bridge A bridge connects two different types of networks together. It translates one network protocol to another protocol. An example of a bridge is a computer modem. A cable modem converts, or bridges, the Ethernet protocol to a cable TV protocol. Network Interface Card (NIC) An NIC (Network Interface Card or Network Interface Controller) is an interface that allows you to connect a device to a network. Many NICs are now integrated into the device’s main circuitry. Network Security Network security is security that controls access to the local area network (LAN) at the logical network boundaries. Network Segment A network segment is any single section of a network that is physically separated from the rest of the network by a networking device such as a switch, router, or hub. A segment may contain one or more hosts. Network Switch A network switch connects multiple devices together so they can communicate with the other devices that are also connected to the switch. As each device is connected, the switch collects and stores the MAC address of the device that it communicates with. When one device wants to communicate with a second device, the switch looks up the destination device's location in its memory, then sends the information to its destination. - 100 - Network Topology A network topology is the physical connection that aids in the communication between devices in an area network. Neutral Conductor See grounded conductor. Noise Noise is any electrical signal present in a circuit other than the desired signal. Noise Masking System A noise masking system actually introduces background noise to hinder communication and increase privacy. You might see this in a healthcare or other information sensitive type environment. These are also sometimes called “sound masking” or “speech privacy systems”. Noisy Ground Noisy ground is an electrical connection to a ground point that produces or injects spurious voltages into the computer system through the connection to ground. Number of Open Microphones (NOM) NOM stands for "number of open microphones." Within the context of PAG - NAG, NOM takes into account the increased possibility of feedback by adding additional live microphones in a space. Each time the number of open microphones is doubled, you lose 3 dB of gain before feedback. Nominal Impedance Nominal impedance is the low point in the usable frequency area in a loudspeaker. - 101 - Non-repudiation Non-repudiation is the concept of keeping accurate records of activity on a network. A nonrepudiated system tracks each person who accessed a system, and what they did while they had access. Notch Filter A notch filter "notches out," or eliminates, a specific band of frequencies. Nyquist-Shannon Sampling Theorem The Nyquist-Shannon Sampling Theorem states that an analog signal can be reconstructed if it is encoded using a sampling rate that is greater than twice the highest frequency sampled. For example, since the range of human hearing extends to 20 kHz, the sampling rate for digital audio should be greater than 40 kHz. O Octave An octave is a band, or group of frequencies. The relationship of the frequencies is such that the lowest frequency is half the highest: 200 Hz - 400 Hz is an octave, 4,000 Hz - 8,000 Hz is an octave. OFF See System State. Ohm's Law Ohm's law defines the relationship between current, voltage, and resistance in an electrical circuit as proportional to applied voltage and inversely proportional to resistance. - 102 - Omni-Directional Omni-directional describes the shape of the area for microphones that have equal sensitivity to sound from nearly all directions. ON See System State. On-Axis On-axis refers to the line perpendicular to the vertical center line of a screen or image. The on-axis position is considered to be the best location for optimum viewing. See also: Viewing Cone, Viewing Angle. Opaque projectors Opaque projectors are projectors that project images from opaque materials onto a screen. Open Systems Interconnection Model (OSI) The Open Systems Interconnection (OSI) model is a reference model defined by ISO (International Organization for Standardization) in ISO/IEC 7498-1, as a conceptual framework of standards for communication in the network across different equipment and applications by different vendors. Network communication protocols fall into seven categories, or “layers.” Each layer builds upon the next. - 103 - Operational Expenditure (Opex) Operating expenditures are expenses a business incurs in day-to-day operations. Examples of opex costs include employee wages, building utilities, and general maintenance of facilities. Operational Security Operational security is the security of site operations, including personnel access and sitespecific manual processes. Optical Screen Material Optical screen material is used in most permanent rear screen applications. This screen system is made up of a series of lenses formed into the screen material. Most common is the two-lens system. Optotype An optotype is a character used to assess a person's visual acuity. It looks like a block letter, and is drawn with specific and rigid geometric rules. Only 10 optotypes are used on the traditional Snellen eye chart: C, D, E, F, L, N, O, P, T, and Z. The perception of five out of six letters (or a similar ratio) is called the Snellen fraction. Operating System (OS) An operating system is a platform which enables software applications to communicate with the CPU. Organic Light-Emitting Display (OLED) An Organic Light-Emitting Display (OLED) is made of layers of organic compounds that emit light when an electric current flows through it. There are separate organic layers for red, green, and blue. OLEDs are emissive devices, meaning they create their own light, as opposed to LCDs, which require a separate light source. As a result, OLED devices use less power but produce a stronger brightness and fuller color than LCDs. - 104 - Oscilloscope An oscilloscope is a test device that allows measurement of electronic signals by displaying the waveform on a CRT. Output An output is a connection point that sends information to another piece of equipment. Outside Sales Outside sales are made when the AV sales professional goes to the customer. These are also known as product or project sales representation. Overcurrent Overcurrent is any current in excess of the rated current of equipment or the ampacity of a conductor. It may result from overload, short circuit, or ground fault. 31 Overcurrent Protection Device An over current protection device is a device such as a circuit breaker or fuse that is designed to open a circuit should the current reach a value that causes excessive or dangerous temperatures in conductors or conductor insulation. Overhead Projector An overhead projector is a device that produces an image on a screen by transmitting light through transparent acetate placed on the stage of the projector. Oversampling Oversampling refers to using a higher sampling rate than what is needed, often significantly higher than the Nyquist frequency. This will increase the rate of the signal, as well as improve resolution, reduce noise, and avoid aliasing and phase distortion. - 105 - Owner The designated responsible party with the authority to make final decisions on contract and technical issues, and provide final acceptance of the energy management plan according to the verification requirement of this standard. Owner Team The Buyer of the AV Systems. End-user, Facility Manager, AV Technology Manager, Building Committee, Purchasing Agent or Contract Representative. P Packet Capture (PCap) PCap, short for “packet capture,” is a low-level library that talks directly to the network card on layer 2, intercepting and capturing all the traffic it finds. Packet Filtering Packet filtering is a firewall technique that uses rules to determine whether a data packet will be allowed to pass through a firewall. Rules are configured by the network administrator, and implemented based on the protocol header of each packet. Packet Switching Packet switching is a method of data transmission in which data is divided into small individual units (i.e., packets) before it is transmitted. Paging System A paging system is a sound system that is used for one-way communication only. It is often used for communicating information to a large audience. The emphasis in a paging system is intelligibility - the clear, one-way communication of an intended message. - 106 - Panelboard A panelboard is a single panel or group of panel units designed for assembly in the form of a single panel, including buses and automatic overcurrent devices, and equipped with or without switches for the control of light, heat, or power circuits; designed to be placed in a cabinet, or cutout box placed in or against a wall, partition, or other support, and accessible only from the front. 32 Parallel Circuit In a parallel circuit the voltage is the same across each load, but the current divides and takes all the available paths and returns to the source. Parallel Loudspeaker Circuit In a parallel loudspeaker circuit, the positive output of the amplifier connects to every loudspeaker's positive terminal, and each loudspeaker's negative terminal connects to the amplifier's negative terminal. Parameter A parameter is a value within computer programming code that defines a function or characteristic of an AV space. Ex: a specific room number stored in the Cloud. - 107 - Parametric Equalizer The parametric equalizer allows discrete selection of a center frequency and adjustment of the width, or Q, of the frequency range that will be affected. This can allow for precise manipulation with minimal impact of adjacent frequencies. Parametric Equalizers allow boost and cut adjustments, and they also allow the user to select the center frequency of the filter as well as adjust the bandwidth of the filter. A parametric equalizer allows the user to create their own filters using individual controls of frequency centering, amplitude, and width of the frequency range (bandwidth) to be controlled. Passive System A passive system is a system that does not require power. Peak The peak is the highest level of signal strength, determined by the height of the signal's waveform. Peaking Peaking is an adjustment method that allows compensation for high frequency loss in cables. Peaking Control Peaking controls are electronic adjustments within a video component that can be used to compensate for system losses, particularly in cable capacitance. Permissible Area Permissible area is the maximum amount of space that cables should occupy inside the conduit. - 108 - Personal Area Network (PAN) A PAN is a limited range wireless network that serves a single person or small workgroup. Phantom Power Phantom power is a means of supplying direct current (DC) to a condenser microphone. The amount of voltage depends upon the microphone. Phase Phase is an interval of time for any periodic function. For a point on a sine wave, it is a measure of that point's distance from the most recent positive-going zero crossing of the waveform. It is measured in degrees, with 0 degrees to 360 degrees being a complete cycle. Phase Alternate Line (PAL) PAL stands for Phase Alternate Line. It is the video standard for much of Europe and Australia. Phoenix Connector Phoenix(R) is a molded plastic, captive screw connector. Termination requires a wire to be stripped and slid directly into a hole on the connector. This creates a compression termination. Phone Connector A phone connector is an audio connector used as a loudspeaker connector. Common types are 1/4 inch and 1/8 inch. Phono Phono is the European name for an RCA connector. - 109 - Phosphor Phosphor is the substance which glows when struck by an electron beam, providing the image in a CRT. The higher the quality of the phosphor, the brighter and more vivid the image. PING See ICMP Echo Request. Pink Noise Pink noise is a random noise source characterized by a flat amplitude response per octave band of frequency (or any constant percentage bandwidth). It has equal energy, or constant power, at each octave. 33 Pink Noise Generator (PNG) A pink noise generator (PNG) is intended to provide an unintelligible noise source that represents an equal amount of energy per octave through a sound system. It is commonly used to evaluate and align a sound system in an environment. Pixel Pixel is an acronym for picture element. The small element used to build a digital image. Plan View A plan view is a drawing of a space from the "top view," taken directly from above. Examples include a floor plan and site plan. Plane of Screen Identification of image position on a plan or drawing relative to other plotted locations. It is a notional line, whether in plan view or elevation, that aligns with the front surface of the screen (i.e., image position) used as a datum to define viewers' relative positions. - 110 - Plasma Display Panel (PDP) A plasma display panel (PDP) is a direct view display made up of an array of cells, known as pixels, which are composed of three subpixels, corresponding to the colors red, green, and blue. Gas in the plasma state is used to react with phosphors in each subpixel to produce colored light (red, green, or blue) from a phosphor in each subpixel. Playback System A playback system is a music reinforcement system that has a wide frequency response bandwidth, and is capable of high sound pressure levels. A playback system does not include microphones; it simply plays prerecorded material. Plenum Space The plenum space is an area connected to air ducts that forms part of the air distribution system. Point-to-Point Point-to-point conferencing is a form of communication in which the two sites are directly linked. Point-Source Point-source is a sound system that has a central location for the loudspeaker(s), mounted high above, intended to cover a large area; typical of a performance venue or a large house of worship. Polar Pattern A polar pattern (or pickup pattern) is the shape of the area that a microphone will be most sensitive to sound. - 111 - Polar Plot A polar plot is a graphical representation of the relationship between a device’s directionality and its output. Polarizer A polarizer is a set of extremely fine parallel lines that act like a net, or filter. They block all light waves that are not parallel to those lines. Polling Polling is a request to a subsystem or a device to send back a specified set of information. Pooled Equipment Any devices that can provide functionality to multiple systems but only to one system at a time (e.g., a videoconferencing codec attached to a shared matrix switcher can be routed to and used with one of the systems). Pooled Equipment The measurement of an AC electric power system defined as the ratio of real power (watts) divided by the apparent power (VA). Power factor is a unitless number between 0.0 and 1.0, typically expressed in a decimal form. A pure resistive load has a power factor of 1.0. Point of Sale (POS) Digital signage located in areas where audiences are focused on making purchases. Point of Sale installations are commonly used to make audiences aware of relevant brand or product information in the context of a shopping experience. Point of Transit (POT) A Point of Transit (PoT) is a digital signage location where audiences are passing from one space to another. PoT locations have a very brief dwell time. - 112 - Point of Wait (POW) A Point of Wait (PoW) is a digital signage location where audiences are idle. POWs have a longer dwell time than other types of location, allowing for longer messages and more complex content. Port In a TCP/IP network, a port is a 16-bit number included in the TCP or UDP Transport Layer header. The port number typically indicates the Application Layer protocol that generated a data packet. A port may also be called by its associated service (e.g., port 80 may be called HTTP, or port 23 may be called telnet). Port Address Translation (PAT) Port Address Translation is a method of NAT (Network Address Translation) whereby devices with private, unregistered IP addresses can access the Internet through a device with a registered IP address. Unregistered clients send datagrams to a NAT server with a globally routable address (typically a firewall). The NAT server forwards the data to its destination and relays responses back to the original client. PAT is also known as One to Many NAT, Network and Port Translation (NAPT), or IP Masquerading. Post Tension Type Construction Post tension type construction is a type of structure that uses metal cables embedded within the concrete slab to support the structure. The cables act as a suspension support system that allows for wider spacing of columns within a building. Potential Acoustic Gain (PAG) PAG (Potential Acoustic Gain) is the potential gain that can be delivered by the sound system without ringing and before feedback occurs. It is based upon the number of open microphones, and the distances between source(s) (like a presenter) and microphone(s), microphones to loudspeakers, and listeners to loudspeakers. - 113 - Power Energy expended in one form manifests itself into another form - motion, heat, or light. This is power, or the rate at which work is done. It is represented by the letter "P" and is measured in watts (W). Power Amplifier A power amplifier boosts the audio signal enough to move the loudspeakers. Power conditioners Power conditioners enhance the quality of power going to equipment by regulating voltage, eliminating noise or correcting other issues. Power Cord The male connector terminates the end of the power cord. The female connector inserts into equipment. Power Distribution Unit (PDU) A power distribution unit (PDU) is a rack-mountable or portable electrical enclosure that is cord or cable connected to a branch circuit for distribution of power to multiple electronic devices. It may contain switches, overcurrent protection, control connections, and receptacles. Power sequencing Power sequencing is the act of powering on & off equipment that often requires warm-up or cool-down time. Sequencing also helps prevent tripping circuit breakers by limiting the excessive surge of electricity when devices are first turned on. - 114 - Preamplifier A microphone preamplifier, also known as a mic pre, amplifies a microphone level signal to line level for routing and processing. Pressurized Cooling Pressurized cooling is a method of cooling in which a rack is pressurized with air, and fans blow cooler air into the rack. Vents on the sides and top of the rack provide an escape for the hot air. Primary Optic Primary optic is the lens that focuses the image onto the screen. Prism A prism beam splitter filters the light into its red, green, and blue components. Processing Amplifiers (Proc Amps) A processing amplifiers (proc amps) is a video processing devices that allows the technician to adjust the luminance, chroma, and hue components of the video signal. Program Meeting A program meeting gathers and exchanges the information necessary to determine which functions are required to support the end users' applications. This information should reveal what the end users currently do, what they need to do, and what they want to do. Program Playback System Program playback systems are used to reproduce a pre-recorded audio program, such as a video soundtrack. - 115 - Program Report A program report is a document that describes the client’s specific needs, system purpose and functionality, and the designer’s best estimate of probable cost, in a non-technical format for review and approval by the owner. Also known as the AV narrative, or discovery phase report, return brief, or concept design report. Programmers Programmers write computer code and design the user interface. Progressive Scanning Scanning that traces the image’s scan lines sequentially, such as in an analog computer monitor. Project A project is a temporary endeavor undertaken to create a unique product, service or result. Temporary means every project has a definite beginning and end. The end can be either fulfillment of objectives or termination of the project. Requirements are often progressively elaborated and must be controlled. Project Client The purchaser of the project's deliverables within the organization requesting the project's existence. Has overall responsibility for the attainment of its operational value (purpose). Project Issues Project Issues are issues that are too big for the Project manager to resolve. Senior Management (Sponsor and Client) must be highly involved in the Project Issue management process. - 116 - Project Management Project Management is the application of knowledge, skills, tools, and techniques to project activities to meet project requirements. It includes: • Identifying requirements • Establishing clear and achievable objectives • Balancing the competing demands for quality, scope, time and cost • Adapting the specifications plans and approach to the different concerns and expectations of the various stakeholders Project Manager The individual with the authority and responsibility for delivering the documented project scope and quality requirements within predictable time and budget targets. Project Sponsor The primary owner of the project within the performing organization who establishes the project's priority.Has overall responsibility for its successful delivery. Project Team Members Functional specialists who use their skills to contribute to the project's deliverables. May work on more than one project at a time as well as operational or maintenance support tasks. Promiscuous Mode Promiscuous mode is a setting in network analyzers. It allows all unicast, broadcast, multicast, and miscellaneous traffic to be sent to a process or capture and analysis. - 117 - Protocol Independent Multicast (PIM) Protocol independent multicast (PIM) allows multicast routing over LANs, WANs, or even, theoretically, the open Internet. Rather than routing information on their own, PIM protocols use the routing information supplied by whatever routing protocol the network is already using: hence, protocol-independent. Pull Tension Pull tension is the maximum amount of tension that can be applied to a cable or conductor before it is damaged. Pure Tone See fundamental frequency. Pulse Width Modulation (PWM) Pulse Width Modulation (PWM) is a DC voltage signal that turns on and off in time. The variations in time are used to create different PWM languages and protocols. Q Q Factor The Q factor is the ratio of the height of the peak of the filter against the width of the filter at the 3 dB point. Quality of Service (QoS) Quality of Service (QoS) is a term used to refer to any method of managing data traffic to preserve system usefulness and provide the best possible user experience. Typically, QoS refers to some combination of bandwidth allocation and data prioritization. - 118 - Querier A querier is a switch or router in a multicast streaming setup that retrieves IGMP membership reports from active hosts. This is a method for a multicast host to know that at least one device on the network is actively listening to the multicast signal. Quiet Ground Quiet ground a point on a ground system that does not inject spurious voltages into the computer sytem, will be termed a "quiet ground." There are no standards to measure how quiet a quiet ground is. R Raceway A raceway is an enclosed channel of metal or nonmetallic materials designed expressly for holding wires, cables, or busbars, with additional functions as permitted in applicable code. Raceways include, but are not limited to, rigid metal conduit, rigid nonmetallic conduit, intermediate metal conduit, liquid-tight flexible conduit, flexible metallic tubing, flexible metal conduit, electrical nonmetallic tubing, electrical metallic tubing, under floor raceways, cellular concrete floor raceways, cellular metal floor raceways, surface raceways, wireways, duct, and busways. 34 Rack Blank Rack blanks are metal strips mounted in empty spaces between pieces of equipment. They direct airflow and aid in rack cooling. Rack Elevation Diagram A rack elevation diagram is a pictorial representation of the front of a rack and the location of each piece of equipment within that rack, typically labeling the number of RUs used for each piece of gear. - 119 - Rack Unit (RU) Rack unit (RU) is a unit of measure of the vertical space in a rack. One RU equals 1.75 inches (44.5 mm). Radio Frequency (RF) Radio frequency (RF) is the portion of the electromagnetic spectrum that is suitable for radio communications. Generally, this is considered to be from 10 kHz up to 300 MHz. This range extends to 300 GHz if the microwave portion of the spectrum is included. Radio Frequency Interference (RFI) Radio frequency interference (RFI) is radiated electromagnetic energy that interferences with or disturbs an electrical circuit. Radio Wave A Radio wave is an alternating current (AC) signal in the form of electrons or photons (wireless), and is classified as electromagnetic energy. These signals, or range of radio frequencies (RF), make up a small section of the electromagnetic spectrum. Any AC signal in the range from 3 kilohertz (kHz) to 300 gigahertz (GHz) falls into the RF spectrum (although, in the U.S., the FCC has not allocated any spectrum below 9 kHz). Random Access Memory (RAM) RAM or Random Access Memory is the most common computer memory used by programs to perform necessary tasks while the computer is on; an integrated circuit memory chip allows information to be stored or accessed in any order and all storage locations are equally accessible. Rarefaction Rarefaction is a decrease in density and pressure in a medium, such as air, caused by the passage of a sound wave. 35 - 120 - Raster Raster is the scanned or illuminated area of a CRT. Ratio A ratio is a mathematical expression that compares two values, e.g. aspect ratio which compares an image's width to its height. A ratio is typically written as X:Y or X/Y. It can also be expressed in decimal notation. For example, 16:9 can be expressed as 1.78. RCA Connector An RCA connector is a non-locking connector commonly used to carry analog video and analog or digital audio signals. It is sometimes called a phono connector or AV jack. Reactance Reactance is the opposition to alternating current resulting from capacitance and inductance in the circuit. Real Power Component of electrical power that performs true work; expressed in watts, it is equal to voltamperes multiplied by the power factor (W=VA*PF). Real-Time Control Protocol (RTCP) Real-Time Control Protocol (RTCP) is a Session Layer protocol used in conjunction with RTP to monitor QoS for streaming flows. RTCP periodically reports on packet loss, latency, and other delivery statistics. - 121 - Real-Time Transport Protocol (RTP) Real-Time Transport Protocol (RTP) is a Transport Layer protocol used in conjunction with UDP to provide additional robustness for streaming applications. RTP packets in include sequence, timing, and source information in addition to the data payload. Rear Screen Projection Rear screen projection is a presentation system in which the image is projected through a translucent screen toward the audience; projecting an image through a translucent screen material for viewing from the opposite side, as opposed to front projection. Read Only Memory (ROM) ROM or Read Only Memory is memory whose contents can be accessed and read but cannot be changed. Permanent memory that can only be entered once, normally by a manufacturer; may not be altered or removed. Reference Level In the context of decibel measurements, the reference level is the established starting point represented by 0 dB. The reference level varies according to linear unit and application. It is typically indicated by the decibel abbreviation: • 0 dB SPL = 0.00002 Pa • 0 dBV = 1 V • 0 dBu = 0.775 V • 0 dBW = 1 W • 0 dBm = 0.001 mW Reference Point Reference point is the point of no potential used as the 0 V (zero volt) reference for a circuit. - 122 - Reflected Ceiling Plan A reflected ceiling plan is used to illustrate elements in the ceiling with respect to the floor. It should be interpreted as though the floor is a mirrored surface, reflecting the features within the ceiling. Reflection Reflection is light or sound energy that has been redirected by a surface. Reflecting Server A reflecting server takes in a unicast stream and broadcasts out a multicast stream. It is often used for live data streams. Reflective Technology Reflective Technology is any display device that reflects light to create an image. Refraction Refraction is the bending or changing of the direction of a light ray when passing through a material, such as water or glass. How much light refracts, meaning how great the angle of refraction, is called the refractive index. Refresh Rate Refresh rate is the number of times per second a display-a monitor, television, or projectorwill draw the image sent to it. Relay Relays are a popular form of binary control, providing on and off functions. A closed relay passes a signal and an open relay stops a signal. - 123 - Release Time The release time of an audio compressor determines how quickly the volume increases when an audio signal returns below the threshold. Relocatable Power Tap Relocatable power tap is a cord-connected product rated 250 VAC or less and 20 A or less with multiple receptables. Intended only for indoor use and plugged directly into a branch circuit for general use. Not intended to be connected to another relocatable power tap. Reserve DHCP Reserve DHCP is a method of establishing static addresses on a DHCP server. Using reserve DHCP, a block of statically configured addresses can be set aside for devices whose IP addresses must always remain the same. The remaining addresses in the subnet may be assigned dynamically. The total pool of dynamic addresses is reduced by the number of reserved addresses. Resistance Resistance is the property opposition of the flow of electrical current. Resistance is measured in ohms. It is typically represented in math by the letter "R" for resistance. Resistor A resistor is a passive electrical component that produces equal impedance to current flow. Current passes through a resistor in direct proportion to voltage, independent of frequency, as outlined in Ohm's Law. Resolution Resolution is the amount of detail in an image and the number of picture elements (pixels) in a display. - 124 - Resource Reservation Protocol (RSVP) Resource Reservation Protocol (RSVP) is a transport layer protocol used to reserve network resources for specific applications. The reservation is initiated by the host receiving the data. It must be periodically renewed by the host in order to be maintained. RSVP is used in combination with Differentiated Service. Retrace Time Retrace time is the time it takes for the electron beam to turn off, travel to its next starting point, then turn back on to begin scanning again. Retro Unit Retro unit is a self-contained rear projection system. Return on Investment (ROI) Return on investment is a concept of performance measurement used to evaluate profits or outcomes in relation to investments. Return on Objectives (ROO) A concept of performance measurement used to evaluate goals met in relation to those expected. Reverberant Field A statistical reverberant field is reverberation that is well enough spatially diffused that it is essentially the same at all points in a room. Many of the formulas we use in acoustics and sound systems assume the existence of a statistical reverberant field, but this does not always exist. When we talk about the reverberation time (RT60) of a room we are assuming the room has a statistical reverberant field. - 125 - Reverberant Sound Reverberant sound is sound waves that bounce off multiple surfaces before reaching the listener, but arrive at the listener's ears quite a bit later than early reflected sound. Reverberation Reverberation is the combination of many acoustic reflections that are dense enough in time so as to not be audible as reflections but instead to act as a statistical sonic decay “tail” to sounds in the room. RF Control RF control is generally employed as a user interface to the control system. Some manufacturers' devices provide control links into their components using RF transmission, as this affords the ability to control devices when line of sight is not possible. RF System An RF system is a closed circuit system that becomes an RF system when the composite video and audio signals are modulated at a certain frequency, called a channel. RF systems require a display device (e.g. TV) with a tuner set to a selected channel to display the information modulated onto that frequency. RGBHV RGBHV refers to a high bandwidth video signal with separate conductors for the red signal, green signal, blue signal, horizontal sync, and vertical sync. RGBS RGBS refers to a four component signal comprised of a red signal, green signal, blue signal, and a composite sync signal. - 126 - RGsB RG S B refers to a three component signal comprised of a red signal, green signal with composite sync added to the green channel, and a blue signal. Often called "sync on green." Rigid Metal Conduit Rigid metal conduit, called rigid, is the heaviest conduit and offers the best physical and EMI protection. Rigid Nonmetallic Tubing Rigid nonmetallic tubing is very stiff with a thick wall, but lightweight. It is similar to plumbing tubing. Because it is not flexible, it is available in pre-formed pieces at various angles. Ring A ring is a network topology that connects terminals, computers, or nodes in a continuous loop. It does not require connectivity to a central hub. Risk A risk is the potential for a problem. A risk exists when there is a probability that a threat will exploit a vulnerability in your system or project. - 127 - Risk Analysis Risk Analysis is a list of risk sources, events, their impact and an assessment of which risks require handling. Risk analysis gives the organization the ability to make informed choices regarding: Threats to respond to Threats to accept Opportunities to pursue Opportunities to ignore. Risk Identification Risk Identification is the process of identifying as many risk events and triggers as possible which may impact the project. Risk identification can be achieved through various methods: Brainstorming Interviewing Checklists / Diagramming Techniques Assumptions Analysis. Room Configuration Room configuration is the overall shape of a space, especially in relation to furniture positions and wall locations. Room Criteria Rating (RC Rating) Developed by Warren Blazier in 1981 and based upon an American Society of Heating, Refrigeration, and Air-Conditioning Engineers (ASHRAE) study of heating, ventilating, and air conditioning noise in office environments. Measurements are taken at eight center octave frequencies from 31.5 to 8,000 Hz and the RC is the average of the measurements taken from 500, 1,000, and 2,000 Hz and includes additional steps to rate the background noise as (N) for neutral, (R) for rumbly or (H) hissy. Room Mode A room mode (a.k.a. standing wave) occurs between parallel surfaces of an enclosure (could be a room, a loudspeaker cabinet, etc.) where the dimension between those parallel surfaces equals one-half wavelength (and the harmonics thereof). The wave is thus reflected back on itself out of polarity creating location specific areas of maximum and minimum pressure. - 128 - Root Cause Analysis Root cause analysis is the ability to isolate and identify a problem and determine the cause of the problem using all of the pertinent available data. Router A router is a device that works on the OSI layer above the network and transport layers. A router knows the IP address of sent packets, and it can send them to specific locations on the network. The IT manager can use a router to change how the network works and allows for redundancy in the network. RS-232 RS-232 is the interface between data terminal equipment and data circuit-terminating equipment employing serial binary data interchange. It supports a single-ended mode of operation with one driver and one receiver. It supports a maximum cable length of 50 feet (15 m) with a data rate of 20 kb/s. RS-422 RS-422 provides the electrical characteristics of balanced voltage digital interface circuits. It is a balanced signal with one driver and 10 receivers with multi-drop capability. The maximum cable length for RS-422 is 4,000 feet (1,220 m) with a data rate of 10 Mb/s. RS-485 RS-485 supports a differential mode of operation with 32 drivers and 32 receivers and multidrop capability. The maximum cable length for RS-485 is 4,000 feet (1,220 m) with a data rate of 10 Mb/s. RsGsBs RsGsBs contain red, green, and blue signals with composite sync added to each color channel; referred to as "RGB sync on all three." It requires three cables to carry the entire signal. - 129 - RT60 RT 60 is the time taken for the energy in an initially steady reverberant sound field to decay by 60 dB after the source of the sound ceases. 36 S Safety Ground See equipment grounding conductor (EGC). Sales or Account Manager Responsible for generating and capturing opportunities that fulfill the client's requirements and generate value for the performing organization.Can be measured based on revenue, anticipated or realized profit, etc. Sampling Rate The sampling rate is how many times, per second, a digital sample is taken of the analog signal. Satellite and Master Antenna Television (SMATV) SMATV is an abbreviation for Satellite and Master Antenna Television system; a television system where satellite and broadcast programs are received via a master antenna array and distributed to users over coaxial cable or fiber optic cable. Satellite Television Satellite television is a method of transmitting television signals. This can be an entertainment or business system such as Direct TV or a signal entity such as a television network distribution center such as CNN, NBC, ESPN, etc. Some major corporations may have their own satellite distribution systems as well. - 130 - Scale Scale is defined as one number being equivalent to another number in a ratio, for example, 1/4 inch = one foot. Scaler A scaler is a feature in a display device that changes the size of an image without changing its shape. Scaling may be required when the image size does not fit the display device. Scan Conversion Scan conversion is the process of changing the horizontal scan rate of one device to that of another. Usually used to describe changing the scan rate of a computer to match the television (NTSC/PAL/SECAM) video format for the purpose of recording or viewing on television video equipment. Scan Rate Scan rate is the frequency of occurrence of a display drawing one line of information. Scattering Scattering occurs when light hits a textured surface, the incoming light waves get reflected in multiple angles because the surface is uneven. Scene A scene or preset is a recallable configuration of lighting levels for one or more zones. Scope Statement A scope statement is a written agreement between the client, the project sponsor, the key stakeholders, and the project team that defines the boundaries of the project. - 131 - Screen Gain Screen Gain describes the reflective properties of a screen. A perfect diffusion screen is used as a reference point as it uniformly reflects light and it is said to have a gain of 1.0. A gain of less than 1.0 typically refers to a screen that is gray instead of white and it is used to increase the contrast of the image. Screens with a gain higher than 1.0 do not scatter the light perfectly but reflect a majority of the light energy back in a specific direction. Higher gain screens are more tolerant of higher ambient light conditions. Section Drawing A section drawing is a view of the interior of a building in the vertical plane. Section drawings show a bisected wall, which allows you to view what is behind it. Secure Remote Management and Monitoring (SRMM) Secure Remote Management and Monitoring (SRMM) is the process of managing a complex array of devices and systems without having to physically interact with any piece of inventory, while ensuring security and accountability. Sensitivity Specification Sensitivity specifications are a way to determine a device's ability to convert one form of energy into another form of energy. It is used to define the device's efficiency in converting from one form to another. Separately Derived System Separately derived system is a premises wiring system whose power is derived from a source of electric energy or equipment other than a service. Such systems have no direct electrical connection, including a solidly connected grounded circuit conductor, to supply conductors originating in another system. Some examples of a separately derived system may include a generator, a battery, converter windings, a transformer, and a solar photovoltaic system provided they "have no direct connection" to another source. 37 - 132 - Séquentiel Couleur Avec Mémoire (SECAM) SECAM stands for Séquentiel Couleur Avec Mémoire (Sequential Color with Memory). It is the video standard in France. Serial Digital Interface (SDI) SDI is an uncompressed, unencrypted, standardized digital video signal. Series/Parallel Loudspeaker Circuit In a series/parallel loudspeaker circuit, groups of loudspeakers called “branches” are wired together in series. Typically, loudspeakers in the same branch have the same impedance. Each branch is connected to the positive and negative lines of the amplifier in parallel. Series Circuit In the series circuit all of the current supplied by the source will flow through the entire circuit. You can think of it this way – all of the electrons leaving the source of power (the negative terminal of the battery in this case) go through each component of the circuit and return to the source (the positive terminal of the battery). While all of the current flows through all of the circuit, the voltage is divided between the three resistors (loads) as well as the wire that connects them. (Wire has resistance therefore it is considered to be a load in the circuit.) - 133 - Series Loudspeaker Circuit In a series loudspeaker circuit, each loudspeaker’s coil is connected to the next loudspeaker in the series, in sequence. The power amplifier’s positive output terminal connects to the positive terminal of the first loudspeaker. The first loudspeaker’s negative terminal connects to the second loudspeaker’s positive terminal. The second loudspeaker’s negative terminal connects to the third loudspeaker’s positive terminal, etc. The last loudspeaker’s negative terminal completes the circuit by connecting to the amplifier’s negative terminal. Server A server is a powerful computer, typically with large amounts of storage and more memory, computing capacity, and redundancy than a desktop computer. Service A service is any means of helping customers achieve their goals without the customer having to directly own all the risks and costs of that means. Service Level Agreement (SLA) A service level agreement (SLA) is used to document agreements between an IT service provider and a customer. It describes the services to be provided; documents service level targets; and specifies the roles and responsibilities of the service provider(s) and the customer(s). An SLA may cover one service or many, and may apply to one customer or many. Service Provider A service provider checks, cleans, maintains, and repairs AV equipment. - 134 - Service Technicians A service technician is a technical professional who performs preventative maintenance, troubleshoots, and repairs systems in the shop or the field. Shared equipment Any devices that provide functionality to multiple systems simultaneously (e.g., a central matrix switcher with inputs and outputs to multiple systems). Shear Shear refers to the tendency of the mount to tear or cut off from the structure. Shield A shield is a metallic partition placed between two regions of space. It is used to control the propagation of electric and magnetic fields from one of the regions to the other. Shields are used to contain electric and magnetic fields at the source or to protect the receiver from electric and magnetic fields. It can be the chassis, or metallic box, that houses an electronic device, or the metallic enclosure (eg., aluminum foil or copper braid), that surrounds a wire or cable. Shipping and Receiving Shipping and Receiving is an administrative office that handles incoming merchandise and operational materials. It also manages the stockroom, ships products, and loads trucks. Short Circuit A short circuit is the electrical connection between any two conductors of the electrical system from line-to-line or from line-to-neutral. (Mike Holt, Basic Electrical Theory). A short circuit is not the same as a ground fault. - 135 - Shotgun Microphone A shotgun microphone is a long, cylindrical, highly sensitive, unidirectional microphone used to pick up sound from a great distance. Sightline A sightline is the unobstructed view between a person and the object he needs to see. A sightline study determines the most appropriate seating layout for a clear field of view, including the lowest visible point on the display wall, nearest viewers’ line of sight, farthest viewers’ line of sight, distortion of image from off-axis seat locations, and other ergonomic factors for a preferred field of vision and viewing comfort tolerances. Signal A signal is the desired information that is sent through the system. Signal Flow Signal flow is the traceable path of signals through a system. In an AV system there are separate “signal flows” for video, audio, and control. Signal Generator A signal generator is a test equipment instrument that produces calibrated electronic signals intended for the testing or alignment of electronic circuits or systems. Signal Ground Signal ground is the 0 V (zero volt) point of no potential that serves as the circuit reference. Signal Management System A signal management system is a group of devices, cables, wires, and connectors that work together to achieve effective signal transfer. - 136 - Signal to Noise Ratio (S/N Ratio) Signal to noise ratio is the ratio, measured in decibels, between the audio or video signal, and the noise accompanying the signal. Simple Network Management Protocol (SNMP) The Simple Network Management Protocol (SNMP) is a set of Internet Engineering Task Force (IETF) standards for network management, including an Application Layer protocol, a database schema, and a set of data objects. SNMP exposes management data in the form of variables on the managed systems, which describe the system configuration. These variables can then be queried, and sometimes set, by managing applications. Simplex As defined by the American National Standards Institute (ANSI) simplex is a form of data transmission wherein communication is available in only one direction. Data is sent from one node to others, but the other nodes cannot respond. The International Telecommunication Union (ITU) uses the term "half-duplex" to refer to this type of data transmission. Single-Phase Power Single-phase power is alternating current electrical power supplied by two current carrying conductors. For residential and some light commercial applications. Single Channel In a measurement scenario, single channel is used to indicate that only one input is used for measurements. No other signals are compared; only the single input is used for measurement. The source signal used for testing is assumed to be of a given type, such as pink noise, and it is not measured. - 137 - Smooth Switcher A smooth switcher monitors the sync information for the second signal, synchronizing the transition when it is in vertical retrace. This feature means that transitions as you go from source to source are clean and transparent. Smooth switchers are used in presentation systems when visual quality should not be compromised. Society of Motion Picture and Television Engineers (SMPTE) SMPTE is an abbreviation for the Society of Motion Picture and Television Engineers. Socket In a TCP/IP network, a socket is the combined port number, Transport Layer Protocol Identifier, and IP addresses of communicating end systems. A socket uniquely identifies a session of a given transport protocol. Software Software is data in the form of a set of instructions that directs a computer to perform specific operations. Solder Solder is a conductive metallic alloy that behaves like a fast acting, very strong glue. Soundfield systems (IR and RF audio) Soundfield systems are sound amplification systems typically used in classrooms to improve the sound distribution or "field of sound" of a teacher's voice. Sound Pressure Level (SPL) In the context of the ANSI/INFOCOMM 1M-2009 Standard, all sound pressure levels are expressed in unweighted dB. - 138 - Sound Pressure Level (SPL) Sound pressure level (SPL) is a measurement of all the acoustic energy present in an environment. It is typically expressed in decibels (dB SPL). Sound pressure refers to the pressure deviation from the ambient atmospheric pressure caused by the vibration of air particles. Sound Pressure Level refers to that variation of level above and below ambient atmospheric pressure and is referenced to 20 µPa or 0.0000204 dynes/cm2, the threshold of human hearing. Sound pressure levels are expressed in decibels to correlate with the human perception of changes in loudness. Sound Reinforcement System Sound reinforcement is the combination of microphones, audio mixers, signal processors, power amplifiers, and loudspeakers that are used to electronically amplify and distribute sound. Source-Specific Multicast (SSM) Source-specific multicast (SSM) allows clients to specify the sources from which they will accept content. This has the dual benefit of reducing demands on the network while also improving network security. Any device that has the host address can try to send traffic to the multicast group, but only content from the specified source will be forwarded to the group. This is in contrast to any-source multicast (ASM), which sends all multicast traffic sent to the host address to all subscribed clients. Speakon Connector Speakon connectors are commonly used to connect amplifiers to speakers in temporary audio system setups. A larger version of this connector is used for power. The connectors are designed with two types of locking systems: Twist loc or Clip lock. - 139 - Specification A specification is a written, precise description of the design criteria for a piece of work. Specifications define the level of qualitative and/or quantitative parameters to be met and the criteria for their acceptance. All specifications must be formulated in terms that are specific, measurable, and verifiable and unambiguous. Specular Reflection A specular reflection is mirror-like; most of the energy is reflected back in a single direction. Speech Privacy Systems Speech privacy system is a sound system that adds background noise to an environment to cover up human speech and prevent privacy issues. Speech Reinforcement System Speech reinforcement systems reinforce or amplify a presenter’s voice so that he or she will be heard over a larger audience. Single-Point Ground (SPG) Single-point ground (SPG), in the context of IEEE Std. 1100, refers to implementation of an isolated equipment grounding configuration for the purposes of minimizing problems caused by circulating current in ground loops. Spherical Aberration Light passing through the edge of a lens can have focal lengths different from light passing through the center. This distortion is called spherical aberration. Splitter A splitter is an electronic device that divides a signal into different pieces to route to different devices. - 140 - Spot Photometer A type of meter used to measure luminance. In the ANSI/INFOCOMM 3M-2011 Standard, the defined specification of such meters includes an acceptance angle of 2° or less. STANDBY See System State. Standard Definition Television (SDTV) Abbreviation for Standard Definition Television. Standing Waves A standing wave occurs between parallel surfaces of an enclosure (this could be a room, a loudspeaker cabinet, etc.) where the dimension between those parallel surfaces equals onehalf wavelength (and the harmonics thereof). The wave is thus reflected back on itself out of polarity creating location specific areas of maximum and minimum pressure. Synonym: Room Mode. Star Ground Star ground is a conductor connection by which separate electrical circuits or equipment are connected to earth at one point (IEEE 1100-2005). Star ground is a grounding configuration where grounds from different circuits are insulated from one another and referenced (connected) to a single point. - 141 - Star Topology A star is a network topology where all network devices are connected to a central network device that is usually a hub or a switch. Static IP Address A static IP address is a manually assigned permanent IP address. Stereophonic Stereophonic, commonly shortened to "stereo," input from all microphones is split into at least two channels before driving the signal through the loudspeakers. Storage Area Network (SAN) A SAN is a high-speed special-purpose network (or subnetwork) that interconnects different kinds of data storage devices. Stranded Conductor A stranded conductor is made of multiple solid conductors of a smaller size that are wound or braided together. The finer the strands, the more flexible the conductor is, which enables easier handling and installation. Streaming media Streaming media is traditionally the transfer of audio & video files which are played at the same time they are temporarily downloaded to a user's computer. - 142 - Streaming Video and Audio Streaming video and audio is a sequence of "moving images" or "sounds" sent in a continuous, compressed stream over the Internet and displayed by the viewer as they arrive. With streaming video or audio, a web user does not have to wait to download a large file before seeing the video or hearing the sound. Subnet A subnet is a logical group of hosts within a local area network (LAN). A LAN may consist of a single subnet, or it may be divided into several subnets. Additional subnets may be created by modifying the subnet mask on the network devices and hosts. Subnet Mask A subnet mask is a binary number whose bits correspond to IP addresses on a network. Bits equal to 1 in a subnet mask indicate that the corresponding bits in the IP address identify the network. Bits equal to 0 in a subnet mask indicate that the corresponding bits in the IP address identify the host. IP addresses with the same network identifier bits as identified by the subnet mask are on the same subnet. For example, subnet mask 255.255.255.0 would indicate that the first three octets of any corresponding IP addresses are the network address and the last octet is the host address. Subsystem An AV subsystem is two or more pieces of AV equipment that work together. Subwoofers Subwoofers are loudspeakers that reproduce lower frequencies, typically 20 Hz - 200 Hz. Super Cardioid Polar Pattern Super cardioids polar pattern is the exaggerated heart-shape of the area that a highly directional microphone is most sensitive to sound. - 143 - Surface Mount Microphone Surface mount microphone is also called a boundary microphone, placed on a table to pick up sound. Used in boardrooms and other environments where a number of talkers must be "picked up" and where the microphone needs to remain unobtrusive. Surround Sound Surround sound are more complex stereo playback systems that use from two to five channels for realistic sound production. The popular term used to describe an experience where the sound 'surrounds' you. This is best achieved using surround-encoded material, a receiver, and surround loudspeakers. S-Video S-Video, also known as Separate Video or Y/C, is a two-channel, standard definition analog video signal. Y (luminance) and C (chrominance) are transmitted on separate conductors. S-Video Connector Typically used for sending and receiving video signals. Found on laptops, S-VHS players and recorders. Switch A switch is a computer networking device that connects devices together on a computer network. It receives, processes, and forwards data packets to their destination host. - 144 - Switcher A switcher is a peripheral or sometimes integrated device used to select one of a group of signals. Sync Sync preserves the time relationship between video frames and correctly positions the image horizontally and vertically. Synchronizer Synchronizers provide sophisticated timing control of workstations for audio-video production and post-production facilities and recording studios. Controllers and synchronizers automate the start, stop and cueing of video tape recorders, hard disk recorders, consoles, editing systems, mixers and other devices. Synthesizers Synthesizers or synths are electronic instruments that mix and modify frequencies or waveforms to create a wide variety of sounds. Syslog Syslog sends real time messages to a log collection server. Essentially, it is a data dump of a system log. System A system is a compilation of multiple individual AV components and subsystems interconnected to achieve a communication goal. - 145 - System Black System Black is the lowest level of luminance a system is capable of producing for its task operating conditions. The system includes projector, screen, the light the projector produces, and ambient light. System Contrast Ratio Contrast expressed as the function of the combination of a projector, screen, and ambient light. System Grounding System grounding is the intentional grounding of one of the current carrying conductors in a manner that will limit the voltage imposed by lightning, line surges, or unintentional contact with higher-voltage lines and that will stabilize that voltage to earth during normal operation (NEC 2008 Handbook). System Integrator A system integrator is responsible for AV system installation, setup, and user training. A system integrator is also known as an Audiovideo Contractor (AVC), installer, or dealer. System Interface Any mechanism used to alter the state of the system (e.g., turning on/off, manual switches, scheduled events, remote control.). A system interface may have, but is not limited to, physical human intervention, and hardware and software providing interaction between the audiovisual system and other systems. - 146 - System State An individual component power state based on the functional requirements of the AV system's operation. DISCONNECTED The AV system components are not consuming any power beyond a minimal amount required to facilitate remote transitioning via the control system to the OFF state. OFF The AV system components are in the most power-conserving mode, still enabling the system to be turned to a power-saving state or an ON state via a system interface. Some system components may be in the ON state while the system is in the OFF state (e.g., control system, processor, Ethernet switch). STANDBY The AV system components are in a power-conserving mode and have a short transition time to the ON state. ON The minimum AV system components required to perform the necessary function are enabled for use. T Table Box/Floor Box A table box or floor box provides the client with a wide range of interface options, from inputs such as component video, to digital and fiber optic. It also provides AC power for notebook computers and network connection points. Tag Protocol Identifier (TPID ) The Tag Protocol Identifier (TPID) is a 16-bit field in the VLAN identifier frame tag defined in IEEE 802.1Q. It distinguishes frames tagged as belonging to a VLAN from untagged frames. The field is set to a value of 0x8100 in order to identify the frame as an IEEE 802.1Q-tagged frame. The TPID is located at the same position as the EtherType/Length field in untagged frames. - 147 - Tap Taps are connections to the transformer windings that allow you to select different power levels from the transformer. Task In the context of a needs analysis, a task is an AV system or process used to support the end user's required application(s). Task Lighting Lighting directed to a specific surface or area that provides illumination for visual tasks. Technical Ground Technical ground is a term used in the audiovisual industry for an isolated ground system. (See isolated ground.) Technical Power 1. Technical power is a term used in the audiovisual industry for lines of power that exclusively serve an audiovisual system. The exact definition is country and projectdependent. 2. (InfoComm experts determine that this term is ambiguous). Technical power is a term used in NEC article 647 entitled "Sensitive Electronic Equipment" referring to a separately derived power system that is 120 volts line-to-line and 60 volts to ground. Technical power is a term used in the audiovisual industry for power that serves an audiovisual system exclusively. Technical Professional A technical professional has specialized knowledge and skills that relate to the AV services the organization provides. - 148 - Technical Trainer A technical trainer is a technical professional who educates other technical professionals on best practices, new technologies, and workplace safety. Tensile Strength Tensile strength is the maximum force that a material can withstand before deforming or stretching. Thin Server A thin server is a server that offers only one service. Typically, a thin server resides on a dedicated hardware or virtualized instance configured with only the functionality required to perform the service. Threat A threat is an entity that might exploit a vulnerability. Three-Phase Power Three phase power is alternating current electrical power supplied by three current carrying conductors, each offset by 120 degrees from one another. A fourth conductor, a neutral, is used as the return conductor. For commercial and industrial applications. Threshold Theshold is the level at which the desired function becomes active. Generally speaking, a lower threshold level means it will activate earlier. Recommended starting threshold for most line level (post preamp) functions is 0dBu. Throw Distance Throw distance is the distance from a projector to a focusing surface or the screen. The measurement point on the projector varies by manufacturer. - 149 - Time and Motion Study A Time and Motion Study is a survey that focuses solely on worker productivity and efficiency. It is a critical evaluation of the actual amount of time it takes for a worker to complete a task, as well as an analysis of the motions taken to complete it. The objective of a time and motion study is to reduce work-load and improve efficiency of a specific process. It does not take human comfort, or ergonomics, into consideration. Time Base Corrector (TBC) Time base corrector (TBC) is the circuitry, or a standalone component, used to stabilize the horizontal lines of an analog video image (typically originating from tape). Time Code Time code is a method of numbering video frames according to SMPTE standards; the 8-digit address representing hour, minute, second, and frame, recorded on the videotape's control track. Time Delay Setting For a dual channel measurement to be accurate, the reference signal must be compared to the measured signal in a common time space. The reference signal must be delayed in time because the measured signal will always lag the reference. The amount of time delay required is based on the time it takes for sound to get from the loudspeaker to the test microphone. Many test instruments have an automated method for calculating the delay time. Time Domain The Time Domain views a signal as amplitude versus time. In other words, you can view the amount of energy over a period of time. It allows you to view the signal over time. In audio, it is used to analyze the loudspeaker response and the acoustic response of the environment. - 150 - Time Window Sometimes referred to as the Time Record, the time window refers to the finite amount of time for the measurement to be initiated and completed. The amount of time is determined by the information needed to be collected, such as the direct sound from the loudspeaker, the frequency resolution desired, or a combination of the loudspeaker and room. In a loudspeaker measurement, the window should be long enough to capture the direct sound, yet short enough that reflections are not included in the measurement. Tip, Ring, Sleeve (TRS) TRS (Tip, Ring, Sleeve) is a three-conductor design of a phone connector that can be terminated as balanced or unbalanced. Tip, Sleeve (TS) TS (Tip, Sleeve) is a two-conductor design of a phone connector used for an unbalanced circuit. Total Cost of Ownership (TCO) Evaluation of sum costs pertaining to implementation, operation, and maintenance of an AV solution. Traffic Policing Traffic policing is a bandwidth management strategy that drops any excess packets beyond a preset maximum throughput. It may be applied to either inbound or outbound traffic. Traffic Shaping Traffic shaping is a bandwidth management strategy that places any excess packets beyond the preset maximum throughput in a queue and schedules them for later transmission. This "smooths out" traffic to a predictable average throughput. Traffic shaping can only be applied to outbound traffic. - 151 - Training and Classrooms Training rooms and classrooms tend to be multi-functional spaces. Participants are seated classroom-style at desks, or theater style in rows of seats. Presentations are given at the front of the room, commonly from a lectern, with the presentation screen to either the right or the left of the presenter. Transduction Transduction is the changing of one type of energy to another. Transfer Function The transfer function is the result of the comparison measurement between the signal input into a device and the signal measured from the output of the device. The device's response, either in time or frequency, is called the transfer function. Note that the transfer function is not the same as the transform between time and frequency domains. Transform A transform function is a mathematical map that views information gathered in one domain, such as the time domain, and it allows you to view it in a different domain, such as the frequency domain. Fast Fourier Transform (FFT) is one such transform function and is used in some audio measurement equipment. Transformer A transformer is a passive electromagnetic device commonly consisting of at least two coils of wire (inductors) with no electrical connection between them. Most often, these coils share an iron-based core. This common core aids in concentrating the magnetic lines of force created by the current flow in one coil (primary), thereby inducing a voltage into the other coil (secondary). Transmission Transmission is the passing of sound energy through partitions or structure borne vibrations. A partition's ability to transmit sound energy will vary with frequency. - 152 - Transmission Control Protocol (TCP) Transmission Control Protocol (TCP) is a connection-oriented, reliable Transport Layer protocol. TCP transport uses two-way communication to provide guaranteed delivery of information to a remote host. It is connection-oriented, meaning it creates and verifies a connection with the remote host before sending it any data. It is reliable because it tracks each packet and ensures that it arrives intact. TCP is the most common transport protocol for sending data across the Internet. Transmission Loss Transmission loss is attenuation that occurs when sound goes through a barrier or partition, expressed in decibels, and is affected by the barrier or partition's mass, stiffness, and damping. Transmissive Technology Transmissive technology is any display device that creates images by allowing or preventing light to pass through it. Transient Disturbance Transient disturbance is a momentary variation in power such as a surge, spike, sag, blackout, noise. or other type of transient. Trap A trap is a mechanism within a subsystem or device programmed to generate an alert after an error or other specified event has taken place. Troubleshooting Troubleshooting is a process for investigating, determining, and settling problems. - 153 - Trough Troughs, also called wireways, are sheet metal wells with hinged or removable covers for housing cables. They are typically used for power and lighting services. Truck Ramps Truck ramps are made of steel, aluminum or fiberglass. They are made to bridge the gap between the truck floor or deck and the ground. TRS Connector A TRS connector (tip, ring, sleeve) is typically used for analog signals including audio. Tweeter Tweeters are loudspeakers that have high frequencies, typically 2,000 Hz - 20,000 Hz. Twisted Pair Twisted pair is any number of wires that are paired together and twisted around each other. They can be shielded or unshielded. U Ultra HD Ultra HD is an umbrella term used to describe video formats with a minimum resolution of 3840 x 2160 pixels in a 16x9 aspect ratio. Two common Ultra HD formats are 4K and 8K. - 154 - Unbalanced Circuit An unbalanced circuit is a two-conductor circuit in which one conductor carries the signal and the other conductor carries the return. The return conductor is usually the cable shield and is a low impedance connection as it is connected to the signal ground and possibly also earth ground. The impedance of the signal circuitry is quite different than the return circuitry, hence the impedance of the two conductors are quite different - the impedances are unbalanced with respect to one another. Uni-directional Communication Uni-directional communication is a system that allows a CPU to communicate with a device. A command is sent to or sent out from a device, but there is no return acknowledgement to verify that the command was executed. Unicast Streaming Unicast streaming is a one-to-one connection between the streaming server sending out the AV data, and client devices listening to the stream. Each client has a direct relationship with the server. The client sends a request to the server, and the server sends the client a stream in response. Since the server is sending out a separate stream for each client, each additional client takes up more bandwidth. Streaming media to three clients at 100 Kbps actually uses 300 Kbps of bandwidth. IP Unicast streams may use either UDP or TCP transport, although with TCP transport, there will always be some buffering. Unity Gain Unity gain is derived from the number 1. Unity gain refers to no change in gain. User Datagram Protocol (UDP) User Datagram Protocol (UDP) is a connectionless, unacknowledged Transport Layer protocol. UDP begins sending data without attempting to verify the origin device’s connection to the destination device, and continues sending data packets without waiting for any acknowledgment of receipt. - 155 - User Interface A user interface is the visual, audible, or other method by which operators of an AV space interact with the systems that control the space. Unshielded Twisted Pair (UTP) Unshielded twisted pair (UTP) cable is typically used for data transfer. It contains multiple 2conductor pairs twisted at regular intervals, employing no external shielding. For more information, see STP (Shielded Twisted Pair). Upstream Upstream refers to devices that are towards the source of content. For example, a DVD player would be upstream of a television. User Interface 1. A type of system interface referring to the method by which humans interact with the operation of the system. Also known as Human Machine Interface (HMI). 2. The user interface is the only part of the control system that the users need to touch. V Value-Added Reseller (VAR) A Value-Added Reseller (VAR) is a dealer that focuses on selling services alongside equipment. Variable Voltage Control The variable voltage control is an analog form of control communication. A voltage of specific parameters is applied to the control point of the device to adjust a level by a specific ratio of voltage value to device level. This is also called a "voltage ramp generator." - 156 - Vectorscope Vectorscope is a specialized oscilloscope used in video systems to measure chrominance accuracy and levels. Vertical Banking Vertical Blanking is the action of turning off the trace on an analog CRT during vertical retrace. Vertical Interval Switcher A vertical interval switcher is a "seamless switcher" that synchronize video transitions when in vertical retrace to ensure that transitions between sources are clean. Vertical Market A vertical market is a group of similar businesses or customers. Vertical Scan Rate The vertical scan rate describes the number of complete fields a device draws in a second. This may also be called the frame rate, vertical sync rate, or refresh rate. The vertical scan rate is measured in hertz (Hz) or cycles per second. Video Video is electronically captured, transported, and displayed images. Videoconferencing Videoconferencing is the live communication of two or more parties via video and audio. - 157 - Videoconferencing Room A videoconferencing room is a space designed for "long distance" meetings. Presentations are made from specific locations in the room, which are transmitted to viewers in different locations. Video Reflector A streaming video reflector (sometimes called a relay) subscribes to a video stream and retransmits it to another address. Video wall A video wall features several monitors, video screens, display cubes, video projectors or TV sets that are set up on top of each other or side by side to form a single, large contiguous display. Viewer A person with normal/corrected vision, or normal visual acuity. 38 Viewing Angle Viewing Angle refers to the maximum off-axis viewer position from which the images on screen are legible. The generally accepted maximum off-axis viewing angle is 45 degrees. Viewing Area Volume of usable viewing space determined by application and design. Viewing Area Plan Plan view drawing of the viewing environment that identifies five viewing locations as defined in the requirements section of the ANSI/INFOCOMM 3M-2011 Standard. - 158 - Viewing Cone Viewing cone is the best viewing area for the audience. The term cone is used because there is width, height, and depth to the best viewing area, and this area emanates from the center of the screen. Visual Field The visual field is the point of space that can be seen when a person’s head and eyes are absolutely still. It is measured in angular magnitude, or degrees. The visual field of a single eye is termed monocular vision and the visual field where the perceived image from both eyes overlap is called binocular vision. Visual Resolution See acuity. Virtual Local Area Network (VLAN) A virtual local area network (VLAN) is created when network devices on separate LAN Segments are joined together to form a logical group that can communicate via switching. Devices on a VLAN form a single, isolated broadcast domain. VOIP Systems VOIP Systems or Voice over Internet Protocol are protocols and technology that allow the digital transmission of phone calls and multimedia over the Internet and other networks. VOIP is relayed over smartphones and other internet devices and requires equipment such as VOIP routers, phone adapters, telephone sets and more. - 159 - Volatile Organic Compounds (VOCs) VOCs, or volatile organic compounds, are the amount of carbon compounds that participate in atmosphere photchemical reactions and vaporize (become a gas) at normal room temperatures, measured in grams per liter. VOCs off-gas from many materials, including adhesives, sealantans, paints, carpets, and particle board. Limiting VOC concentrations protects the health of both construction personnel and building occupants. 39 Volt Volt is the basic international unit of potential difference or electromotive force; symbolized by an upper case V. Voltage Voltage is the electrical potential to create current flow in a circuit. It is represented in math by the letter "V" for "volts" or "E" for "electromotive force." Virtual Private Network (VPN) A virtual private network (VPN) uses the Internet to create a tunnel between two or more local area networks (LANs). VPNs are used to create virtual wide area networks (WANs), and for remote monitoring, troubleshooting and control. VPNs are typically controlled and configured by the enterprise network administrator. Each host requires the proper software, access rights, and password to log into the client network. Vulnerability A vulnerability is a specific weakness in a system. W Watt A Watt is the measurement of the amount of power consumed by a system. It's represented in math by the symbols "P" or "w." - 160 - Waveform Monitor Waveform monitor is a specialized oscilloscope used to display and analyze the video signals sync, luminance, and chroma levels. Wavelength Wavelength is the distance between two corresponding points of two consecutive cycles. Wayfinding Wayfinding is the use of visual guides or signage in strategic locations to help travelers more easily navigate to a destination. Webcasting Webcasting allows the broadcast of digital media such as audio or video over the Internet, which audience members can stream live or access on demand. Essential equipment for webcasting includes computers, streaming servers, production software, recording gear, appliances and more. Webconferencing Webconferencing combines audioconferencing with computer graphics for sharing over the Internet. Web Service Integration (WSI) Web Service Integration (WSI) is an interdevice communication method that treats every device or subsystem on a network as a "service." Any other device or system on the same network can interact with the service through "Post" or "Get" messages through the XML protocol using open standards of message formatting. White Noise White noise is a sound that has the same energy level at all frequencies. - 161 - Wide Area Network (WAN) A wide area network (WAN) is a network that spans large geographical distances, connecting several local area networks (LANs) via leased line, packet switching, virtual private network (VPN), or other means. LANs are connected to a WAN through use of a router. Window Function The Fourier transform requires that the signal value be at zero at the beginning and at the end of the measurement. To prevent truncation errors, the window function determines how the endpoints of the measurement are brought to their zero value. There are numerous types of window functions, and some examples include Gaussian, Hamming, Hanning (Hann), Blackman, Blackman-Harris, etc. Use the window function recommended by the manufacturer of the measurement system. Note that the window function is not the same as time windowing. Wire Wire is a single conductive element intended to carry a voltage or electronic signal. Wired Microphone A Wired Microphone is directly connected to the audio mixer by a cable terminated with XLR connectors. These microphones tend to be used at fixed locations, such as on a gooseneck attached to a lectern or on a table stand at a panel table. Wireless Local Area Network (WLAN) WLAN or Wireless Local Area Network is a network that shares information by radio frequency (RF). Wireless Microphone Wireless Microphone systems require two parts: a transmitter and a receiver. The microphone is directly wired to a transmitter which operates on a battery. - 162 - Woofer Woofers are loudspeakers that have low frequencies, typically 20 Hz - 200 Hz. Work Breakdown Structure (WBS) The work breakdown structure is a deliverable-oriented grouping of project elements which will ultimately organize and define the total scope of the project. Each descending level represents an increasingly detailed definition of a project component. X XLR Connector An XLR connector is a popular type of audio connector featuring three leads: two for the signal and one for overall system grounding. A secure connector often found on high quality audio and video equipment; sometimes called a Canon connector. XLR or Cannon Connector Used for sending audio signals, control signals, and supplying power. Found on microphones, mixers, amplifiers and other audio processing devices. Y Y/C Y/C is a video signal, also known as S-Video. Y is the luminance and C is the chrominance. Y and C are transmitted on separate synchronized conductors. - 163 - Z Zero Reference InfoComm experts determine that this term is ambiguous. See reference point (circuits) or reference level (decibels). Zoom Lens A zoom lens is a lens that allows the operator to adjust focal length for sizing or distance. - 164 - Sources 1 Morfey, Christopher. "The Dictionary of Acoustics". Dictionary of Acoustics, 2000, Academic Press. 2 NES Handbook, 8th Edition, page 87. 3 Nomenclature and Definitions for Illuminating Engineering, 2010, Illuminating Engineering Society. 4 Julius Panero and Martin Zelnik . Adapted from Human Dimension & Interior Space. 5 Xiaozheng Lu. " Understanding HDMI Eye Pattern, BER, and Cliff Effect". http://www.audioquest.com/resource_tools/downloads/whitepapers/HDMI_eyepattern_B ER_and_cliffeffect_rev_1_00.pdf. August 28, 2007. Audioquest. 6 NEC 2008 Handbook. 7 United States National BIM Standard V1 P1, Jan 2008. 8 Fruin. Pedestrain Planning and Design, 1971. 9 Fundamentals of Lighting for Videoconferencing. 2005. Illuminating Engineering Society. 10 Rane Pro Audio Reference. 11 Madsen, David A., Engineering Drawing and Design, 5th ed, 2012. Delmar Cengage Learning. 12 ANSI/IES RP-16-10 Nomenclature and Definitions for Illuminating Engineering. 2010. Illuminating Engineering Society. 13 Fundamentals of Lighting for Videoconferencing. 2005. Illuminating Engineering Society. 14 NEC 2008 Handbook. 15 Rane. 16 Handbook for Sound Engineers, 4th Edition. 17 Audio Dictionary. 18 NEC 2008 Handbook. 19 NEC 2008 Handbook. 20 NEC 2008 Handbook. 21 NEC 2008 Handbook. - 165 - 22 http://tools.ietf.org/html/rfc4604. 23 ASHRAE Standard: Ventilation for Acceptable Indoor Air Quality. 24 Ballou, Glen M., Handbook for Sound Engineers, 3rd ed. 2002. Page 1241-1242. Focal Press. 25 Kendall, Neal, Troubleshooting HDMI Systems: Diagnostic Principles & Techniques. 2011. CEDIA and Quantum Data. 26 Ballou, Glen M., Handbook for Sound Engineers, 3rd Ed. Page 1249. 27 Handbook for Sound Engineers, 4th Edition. 28 NEC 2008 Handbook. 29 Julius Panero and Martin Zelnik, Human Dimension: Interior Space. 30 Rane. 31 NEC 2008 Handbook. 32 NEC 2008 Handbook. 33 Rane Pro Audio Reference. 34 NEC 2008 Handbook. 35 Rane Pro Audio Reference. 36 Dictionary of Acoustics. 37 NEC 2008 Handbook. 38 “Visual Acuity Measurement Standard". 1984. The International Council of Ophthalmology. 39 Green Building and LEED Core Concepts Guide. - 166 -
