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Principles of Telecommunications Technology Chapter 2 Objectives In this chapter, you will: Describe the principles of electricity that underlie all telecommunications signaling Explain the concepts of current and voltage as they apply to telecommunications technology Describe the components on an integrated circuit Explain the difference between analog and digital transmission Use binary encoding to represent decimal numbers 2 Modified by : Brierley 5/23/2017 Describe various electricity and data transmission measurements Atomic Charges Charge - the characteristic of a material that enables it to exert force on another material. Neutrons - found at the center of an atom, possess no charge and are said to be neutral. Protons - found at the center of an atom along with neutrons, carry a positive charge. Electrons - orbit the center of an atom and carry a negative charge 3 Modified by : Brierley 5/23/2017 Atomic Charges 4 Modified by : Brierley 5/23/2017 Static Electricity Static electricity - the release of an accumulated charge in some material or object. Because the charges inherent in electrons and protons are bound to balance each other through static electricity, these charges are also called electrostatic charges. 5 Modified by : Brierley 5/23/2017 Electric Current Electric current - the controlled movement of an electrical charge (or electrons) along the atoms of a conductor. Circuit - a closed connection between an electric source (such as a battery) and a load (such as a lamp) over which current may flow. Signal - occurs when current manipulated to transmit information. 6 Modified by : Brierley 5/23/2017 Electric Current Voltage - the pressure that the electric current exerts on its conductor is known. It is commonly equated to the strength of the electric current, and is measured in volts Amperes - the amount of current (or charge flowing through a wire each second ) is measured in amperes, abbreviated as amps. Resistance - a material’s opposition to electric current. 7 Modified by : Brierley 5/23/2017 Electric Current 8 Modified by : Brierley 5/23/2017 Conductors and Insulators Conductor - a material over which electric current readily flows. Grounding - the use of a conductor (such as a wire) to divert unused or potentially harmful charges to an insulator, where they will be stopped or absorbed. Insulators - materials that do not allow electric current to flow easily. Semiconductor - conducts electricity better than an insulator, but not as well as a conductor. 9 Modified by : Brierley 5/23/2017 Conductors and Insulators 10 Modified by : Brierley 5/23/2017 Resistance 11 Modified by : Brierley 5/23/2017 Calculating Voltage, Amps, and Resistance with Ohm’s Law 12 Modified by : Brierley 5/23/2017 Direct and Alternating Current Direct current (DC) - an electrical charge flows steadily in one direction over the conductor. 13 Modified by : Brierley 5/23/2017 Direct and Alternating Current Alternating current (AC) - the electrical charge flows in one direction first, then in the opposite direction, then back in the first direction, and so on, in an alternating fashion over the conductor. 14 Modified by : Brierley 5/23/2017 Direct and Alternating Current 15 Modified by : Brierley 5/23/2017 Direct and Alternating Current 16 Modified by : Brierley 5/23/2017 Capacitance The ability for an electric circuit or component to accumulate or store a charge. Capacitance is measured in Farads (abbreviated as F), a unit named after English chemist and physicist Michael Faraday, who experimented with electricity in the early 1800s. Capacitor - a device that stores electrical charge (as the tank stores water). 17 Modified by : Brierley 5/23/2017 Capacitance 18 Modified by : Brierley 5/23/2017 Capacitance 19 Modified by : Brierley 5/23/2017 Capacitance 20 Modified by : Brierley 5/23/2017 Capacitance 21 Modified by : Brierley 5/23/2017 Inductance 22 Modified by : Brierley 5/23/2017 Inductance 23 Modified by : Brierley 5/23/2017 Inductance 24 Modified by : Brierley 5/23/2017 Inductance 25 Modified by : Brierley 5/23/2017 Inductance 26 Modified by : Brierley 5/23/2017 Inductance 27 Modified by : Brierley 5/23/2017 Electrical Power 28 Modified by : Brierley 5/23/2017 Electrical Power 29 Modified by : Brierley 5/23/2017 Measuring Electricity 30 Modified by : Brierley 5/23/2017 Measuring Electricity 31 Modified by : Brierley 5/23/2017 Measuring Electricity 32 Modified by : Brierley 5/23/2017 Passive Electronic Devices Passive device - a component that contributes no power gain to a circuit. Resistor - a component inserted into a circuit to provide a specific amount of resistance 33 Modified by : Brierley 5/23/2017 Diodes 34 Modified by : Brierley 5/23/2017 Diodes 35 Modified by : Brierley 5/23/2017 Transistors 36 Modified by : Brierley 5/23/2017 Integrated Circuits Circuits that combine the conductor and the attached components of a circuit in one small unit. 37 Modified by : Brierley 5/23/2017 Analog Transmission Analog electromagnetic signals that continuously vary in their strength and speed. 38 Modified by : Brierley 5/23/2017 Transmission Flaws Noise - unwanted interference from external sources, which can degrade or distort a signal. Attenuation - the loss of a signal’s strength as it travels away from its source. Amplifier - an electronic device that increases the voltage, or power, of the signals. Regeneration - when digital signals are repeated, they are actually retransmitted in their original, pure form, without any noise. Repeater - a device that regenerates a digital signal. 39 Modified by : Brierley 5/23/2017 Transmission Flaws 40 Modified by : Brierley 5/23/2017 Transmission Flaws 41 Modified by : Brierley 5/23/2017 Encoding and the Numbering System Encoding - the process of modifying data so that it can be interpreted by the receiver. Methods for encoding data include: The Decimal System The Binary System Hexadecimal System EBCDIC ASCII UNICODE 42 Modified by : Brierley 5/23/2017 Measuring Data 43 Modified by : Brierley 5/23/2017 Throughput and Bandwidth Throughput - the amount of data that a communications channel can carry during a given period of time. The physical nature of every communications channel determines its potential throughput. Bandwidth - a measure of the difference between the highest and lowest frequencies that a media can transmit. 44 Modified by : Brierley 5/23/2017 Summary Electricity may exist as either static electricity, the imbalance of charges, or as current electricity, the flow of charge along a conductor. The three main characteristics of a circuit are voltage, current, and resistance. If two of these characteristics are known, the third can be calculated using Ohm’s Law. Electronic devices may be active or passive. Examples of passive devices are capacitors and inductors. Examples of active devices are transistors and diodes. 45 Modified by : Brierley 5/23/2017 Telecommunications Principles END 46 Modified by : Brierley 5/23/2017