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PGT110 – MULTIMEDIA
TECHNOLOGY
Lecturer/PLV :
Email :
Mobile :
Mohd Fisol Bin Osman
[email protected]
019 - 3528363
Date and Time
 Lecture
Monday : 5 PM to 7 PM (2 Hours)
 Laboratory/Tutorial Session (3 Hours)
Divided into two groups :
Group 1 : Friday 4 PM to 7 PM
Group 2 : 12 Noon to 3 PM
Attendance will be recorded !
Course Outcomes (Cos)
 CO1 :
Ability to identify the fundamentals and concepts
of data, voice and video communications and the criteria
for choosing a communications medium.
 CO2 :
Ability to explain how networking media, devices and
software work together to provide data, voice and video
networking services and describes the benefits of various
types of media.
COs Continue..
 CO3 :
Ability to list and analyze wireless telecommunications
technologies and its structure
 CO4 :
Ability to evaluate and propose basic telecommunication
design structure based on conditions given
Course Contents
Chapter 1 – Overview of
Multimedia Systems (Concepts
and Definations)
 Dedicated, switched, and virtual circuits
 Two wires vs four wires circuits
 Analog vs Digital
 Amplifiers, Repeaters
 Modem and Codecs
 Multiplexers and Switchers
 Signaling and Controls
Preface
“What is the transmitter? It is an electrical ear which
receives the shock of the dancing molecules, just as does
the membrane of the human ear. . . . What is the
receiver? It is an electric mouth which can utter human
sounds. “
John Mills, The Magic of Communication: A Tell - You - How Story,
Information Department, American Telephone and Telegraph
Company
Telecommunications
General definition:
Telecommunications is the transfer of information ( communications ) from a
transmitter or sender to a receiver across a distance ( tele ) through a
transmission medium
 Electromagnetic energy is employed to represent the data, usually through a
physical/transmission medium,
such as:
 copper wire or glass fibre
What else?.
wired/ wireless ?
NEXT : INFORMATION
Information
 Information can be in many form
- electromagnetic energy
 Electric impulse
 Radiated energy
 The information can retain its original, or native, form during
transmission.
 Alternatively, the transmission process can alter the data in
some way in order to effect compatibility between the
transmit and receive devices and with various intermediate
network elements.
List several types/forms of information :
Information (Cont.)
 Audio/Voice
 Human voice, CDs, tape, records, radio etc
 Video
 movies, graphics and animation
 Data
 Emails, messages etc
 Image
 Combinations/Multimedia
Intermediate devices
 to establish and maintain the connection and to support the
information transfer.
Examples:
 modems or codecs,
 controllers,
 multiplexers
 bridges, switches, routers,
 Gateways
 ETCs..
Communication System
Transmitter
 The transmitter is a collection of electronic components
and circuits that converts the electrical signal into a signal
suitable for transmission over a given medium.
 Transmitters are made up of oscillators, amplifiers, tuned
circuits and filters, modulators, frequency mixers,
frequency synthesizers, and other circuits.
Communication Channels/
Transmission Mediums
 The communication channel is the medium by which
the electronic signal is sent from one place to another.
 Types of media include
 Electrical conductors
 Optical media
 Free space
Receivers
 A receiver is a collection of electronic components
and circuits that accepts the transmitted message
from the channel and converts it back into a form
understandable by humans.
 Receivers contain amplifiers, oscillators, mixers,
tuned circuits and filters, and a demodulator or
detector that recovers the original intelligence signal
from the modulated carrier
Transceivers
 A transceiver is an electronic unit that incorporates
circuits that both send and receive signals.
 Examples are:
• Telephones
• Fax machines
• Handheld CB radios
• Cell phones
• Computer modems
Noise
 random, undesirable electronic energy that enters the
communication system via the communicating medium and
interferes with the transmitted message.
Communication Systems – In
Depth
Souce
Other words for transmitter
 Device that originates the information transfer.
 Transmitters include voice telephones, data terminals,
host computer systems, and video cameras.
Sink
Other word for receiver/ destination
 target device, or destination device, that receives the
information transfer.
 Receivers can include telephones, data terminals, host
computers, and video monitors.
 Most devices are capable of both transmitter and
receiver functions (source/sink)
Circuit
 a communications path, over an established medium, between two
or more points, from end to end, between transmitter and receiver
 logical connection over a physical line
 Might include path, link, line , and channel , although such usage
can be specifi c to the underlying technology
 Circuits also may be for purposes of either access (from the
customer premises to the edge of the carrier network) or
transport (circuits are employed in the core , or backbone , of the
network for purposes of long - haul transmission)
 simplex (one - way), half - duplex (two - way, but only one way at
a time), or full - duplex (simultaneous two - way)
Link
 two - point segment of an end - to - end circuit (e.g.,
from terminal to switch or from switch to switch)
 Either single link or multiple links
 Example:
between a host computer and a peripheral,
such as a printer
Line
 Has several definitions
 In a Private Branch eXchange (PBX) environment, a
station line refers to the connection between the PBX
switch and the station user ’ s terminal equipment, such
as telephone, fax machine etc.
 In rate and tariff terminology, line refers to a local loop
connection from the telephone company Central Office
(CO) switch to the user premises in support of
Customer Premises Equipment (CPE) other than a
switch.
Trunk
 a communications circuit, available to share among
multiple users, on a pooled basis and with contention
for trunk access managed by an intelligent switching
device
 trunks interconnect switches
 Trunks are directional in nature, with the options being
one - way outgoing (originating), one – way incoming
(terminating), or two - way (combination).
Dedicated, Switched and Virtual
Circuits
Dedicated Circuits between Seattle terminal and
New York Mainframe
Dedicated Circuits
 physical circuits dedicated to directly connecting devices
(e.g., PBXs and host computers) across a network
Advantages:
 serve a single - user organization only, rather than serving
multiple users
 Ability to condition dedicated circuits to deliver specific levels
of performance by adding amplification or other signal
processing enhancements to the line to optimize its
transmission characteristics, whereas you generally cannot
do so with switched circuits (not from end to end).
Dedicated circuits
Disadvantages:
 In terms of network efficiency because that circuit is taken out of
shared public use and, therefore, is unavailable for use in support
of the traffic of other users
 rather expensive - with their costs being sensitive to distance and
capacity
 susceptible to disruption, backup circuits often are required to
ensure effective communications in the event of either a
catastrophic failure or serious performance degradation.
 Could be difficult and lengthy design and configuration process. –
for huge connections
Switched Circuits
Example of circuit switched connections
Switched Circuits
 More flexible
Virtual Circuits
 logical, rather than physical, circuits.
 are established through the network based on options
and instructions defined in software routing tables
 Divided into two:
- Permanent Virtual Circuits (PVCs)
- Switched Virtual Circuits (SVCs)
 Will learn more in chapter 10 !..Broadband Network
Services
Two wires vs Four wires Circuit
Comparison of Two wires and Four wires Circuits
Two wires circuit
 carry information signals in both directions over the same
physical link or path
 The use of a single twisted pair, copper wire connection
 two wires are required to complete the electrical circuit, with
the current in one wire opposite to the current in the other,
and both wires carry the information signal
 generally cover a short distance
 gener-ally they are analog in nature; therefore, error
performance (quality) is relatively poor
Four wire circuit
 carry information signals in both directions over
separate physical links or paths and in support of
simultaneous, two - way transmission.
 Traditional – used copper wires, nowadays over a
variety of transmission media, including twisted pair,
coaxial cable, or fiber optic cable
 can be established without the use of any wires at all,
as in the case with a circuit established over
microwave, satellite, or infrared transmission systems.
Four wire circuit
Advantages :
 Can accommodate multiple, simultaneous
communications in a full - duplex mode, all
multichannel circuits are four wire. Multichannel
capability
 greater bandwidth, or capacity
 digital, rather than analog – improve error performance
Bandwidth
 measure of the capacity of a circuit or channel
 the total frequency on the available carrier for the
transmission of data.
 While the information signal (bandwidth usable for data
transmission) does not occupy the total capacity of a
circuit, it generally and ideally occupies most of it.
 The balance of the capacity of the circuit may be used
for various signaling and control (overhead ) purposes
Carrier
 continuous signal on a circuit that is at a certain
frequency or within a certain frequency range
 support of the information bearing signal (i.e., it carries
the information signal), which the transmitter impresses
on the carrier by varying the signal in some fashion and
which the receiver must detect and interpret
 support signaling and
 control information used to coordinate and manage
various aspects of network operations
Types of Communications
TX
Channel
TX
RX
RX
Channel(s)
RX
TX
Simplex:
One-way
Two-way
Half duplex:
Alternate TX/RX
Duplex:
Full duplex:
Simultaneous
TX/RX
Types of Communication Signals
Analog - smooth and continuous voltage variation.
Digital - binary or two voltage levels.
Time
Communications Signal Variations
 Baseband - The original information signal such
as audio, video, or computer data. Can be
analog or digital.
 Broadband - The baseband signal modulates or
modifies a carrier signal, which is usually a sine
wave at a frequency much higher than the
baseband signal.
Basic analog communications system
Baseband signal
(electrical signal)
Input
transducer
Transmitter
EM waves (modulated
signal)
Transmission
Channel
Modulator
EM waves (modulated
signal)
Carrier
Baseband signal
(electrical signal)
Output
transducer
Receiver
Demodulator
MODULATION
 An electronic technique in which a
baseband information signal modifies a
carrier signal (usually a sine wave) for
the purpose of frequency translation and
carrying the information signal via radio.
 The common types of modulation are
amplitude, frequency and phase.
Why modulation is needed?
 To generate a modulated signal suited and compatible to the
characteristics of the transmission channel.
 For ease radiation and reduction of antenna size
 Reduction of noise and interference
 Channel assignment
 Increase transmission speed
Modulation at the transmitter
AMPLITUDE MODULATION
The modulating (baseband) signal is a sinusoid in this example.
High-frequency carrier, normally much
higher than the baseband frequency
FREQUENCY MODULATION
The baseband signal controls the carrier’s frequency
and the carrier’s amplitude remains constant.
Carrier
Resting fc
Increasing fc
Decreasing fc
Increasing fc
Resting fc
Modulating signal
FM
MULTIPLEXING
 Multiplexing (MUX or MPX) - the process
of simultaneously transmitting two or
more baseband information signals over a
single communications channel.
 Demultiplexing (DEMUX or DMPX) - the
process of recovering the individual
baseband signals from the multiplexed
signal.
MULTIPLEXING AND
DEMULTIPLEXING
Single communications channel (radio or cable)
MUX
Original baseband
information signals
DEMUX
Recovered baseband
information signals
Modulation and Multiplexing
FREQUENCY AND WAVELENGTH
 Cycle - One complete occurrence of a
repeating wave (periodic signal) such as
one positive and one negative alternation
of a sine wave.
 Frequency - the number of cycles of a
signal that occur in one second.
 Period - the time distance between two
similar points on a periodic wave.
 Wavelength - the distance traveled by an
electromagnetic (radio) wave during one
period.
PERIOD AND FREQUENCY
COMPARED
T = One period
time
One cycle
Frequency = f = 1/T
Frequency and wavelength compared
+
T
0
time
f = 1/T

distance
CALCULATING WAVELENGTH
AND FREQUENCY
 = 300/f
f = 300/
 = wavelength in meters
f = frequency in MHz
(f = 300/)
Frequency
300 GHz
30 GHz
VHF UHF SHF EHF
Millimeter
waves
10-4 m
10-3 m
10-2 m
10-1 m
1m
10 m
102 m
103 m
104 m
105 m
106 m
107 m
Wavelength
3 GHz
HF
300 MHz
MF
30 MHz
LF
3 MHz
VLF
300 kHz
VF
30 kHz
ELF
3 kHz
300 Hz
30 Hz
THE ELECTROMAGNETIC SPECTRUM
FROM 30 HZ TO 300 GHZ
( = 300/f)
LOW AND MEDIUM
FREQUENCIES
 Extremely Low Frequencies - 30 to 300 Hz
 Voice Frequencies - 300 to 3000 Hz
 Very Low Frequencies - 3 kHz to 30 kHz
 Low Frequencies - 30 kHz to 300 kHz
 Medium Frequencies - 300 kHz to 3 MHz
HIGH FREQUENCIES
 High Frequencies




- 3 MHz to 30 MHz
Very High Frequencies
- 30 MHz to 300 MHz
Ultra High Frequencies
- 300 MHz to 3 GHz
(1 GHz and above = microwaves)
Super High Frequencies
- 3 GHz to 30 GHz
Extremely High Frequencies
- 30 GHz to 300 GHz
300 GHz
Cosmic rays
Gamma rays
X-rays
Ultraviolet
Visible
Infrared
Millimeter
waves
0.4 x 10-6 m
0.8 x 10-6 m
10-5 m
10-4 m
10-3 m
THE ELECTROMAGNETIC
SPECTRUM ABOVE 300 GHZ
Wavelength
OPTICAL FREQUENCIES
 Infrared - 0.7 to 10 micron
 Visible light - 0.4 to 0.8 micron
 Ultraviolet - Shorter than 0.4 micron
Note: A micron is one millionth of a meter.
Light waves are measured and expressed
in wavelength rather than frequency.
Limitations in communication
system
 Physical constraint
-Delay, attenuation, bandwidth limitation, etc
 Technological constraint
- hardware.
- Expertise
- economy, law
Frequency Spectrum &Bandwidth
 The frequency spectrum of a waveform consists of all
frequencies contained in the waveform and their
amplitudes plotted in the frequency domain.
 The bandwidth of a frequency spectrum is the range of
of frequencies contained in the spectrum.It is calculated
by subtracting the lowest frequency from the highest.
Frequency Spectrum &Bandwidth
(cont’d)
 Bandwidth of the information signal equals to the
difference between the highest and lowest frequency
contained in the signal.
 Similarly, bandwidth of communication channel is the
difference between the highest and lowest frequency
that the channel allow to pass through it