Principles of Telecommunications Technology

Principles of Telecommunications TechnologyChapter 2

ObjectivesIn 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

Describe various electricity and data transmission measurements

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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

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Atomic Charges

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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.

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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.

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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.

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Electric Current

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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.

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Conductors and Insulators

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Resistance

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Calculating Voltage, Amps, and Resistance with Ohm’s Law

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Direct and Alternating Current

Direct current (DC) - an electrical charge flows steadily in one direction over the conductor.

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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.

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Direct and Alternating Current

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Direct and Alternating Current

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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).

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Capacitance

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Capacitance

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Capacitance

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Capacitance

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Inductance

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Inductance

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Inductance

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Inductance

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Inductance

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Inductance

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Electrical Power

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Electrical Power

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Measuring Electricity

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Measuring Electricity

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Measuring Electricity

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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

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Diodes

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Diodes

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Transistors

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Integrated Circuits

Circuits that combine the conductor and the attached components of a circuit in one small unit.

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Analog Transmission

Analog - electromagnetic signals that continuously vary in their strength and speed.

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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.

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Transmission Flaws

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Transmission Flaws

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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

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Measuring Data

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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.

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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.

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Telecommunications Principles

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