Download Principles of Telecommunications Technology

Principles of
Telecommunications
Technology
Chapter 2
Objectives
In this chapter, you will learn to:
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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
Atomic Charges
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Charge - the characteristic of a material that enables it to
exert force on another material.
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Neutrons - found at the center of an atom, possess no
charge and are said to be neutral.
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Protons - found at the center of an atom along with
neutrons, carry a positive charge.
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Electrons - orbit the center of an atom and carry a
negative charge
Atomic Charges
Static Electricity
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Static electricity - the release of an
accumulated charge in some material or object.
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Because the charges inherent in electrons and
protons are bound to balance each other
through static electricity, these charges are also
called electrostatic charges.
Electric Current
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Electric current - the controlled movement of
an electrical charge (or electrons) along the
atoms of a conductor.
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Circuit - a closed connection between an
electric source (such as a battery) and a load
(such as a lamp) over which current may flow.
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Signal - occurs when current manipulated to
transmit information.
Electric Current
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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
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Amperes - the amount of current (or charge flowing
through a wire each second ) is measured in
amperes, abbreviated as amps.
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Resistance - a material’s opposition to electric
current.
Electric Current
Conductors and Insulators
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Conductor - a material over which electric current readily
flows.
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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.
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Insulators - materials that do not allow electric current to
flow easily.
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Semiconductor - conducts electricity better than an
insulator, but not as well as a conductor.
Conductors and Insulators
Resistance
Calculating Voltage, Amps, and
Resistance with Ohm’s Law
Direct and Alternating Current
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Direct current
(DC) - an electrical
charge flows
steadily in one
direction over the
conductor.
Direct and Alternating Current
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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.
Direct and Alternating Current
Direct and Alternating Current
Capacitance
The ability for an electric circuit or component to
accumulate or store a charge.
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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.
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Capacitor - a device that stores electrical
charge (as the tank stores water).
Capacitance
Capacitance
Capacitance
Capacitance
Inductance
Inductance
Inductance
Inductance
Inductance
Inductance
Electrical Power
Electrical Power
Measuring Electricity
Measuring Electricity
Measuring Electricity
Passive Electronic Devices
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Passive device - a
component that
contributes no
power gain to a
circuit.
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Resistor - a
component inserted
into a circuit to
provide a specific
amount of
resistance
Diodes
Diodes
Transistors
Integrated Circuits
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Circuits that combine
the conductor and
the attached
components of a
circuit in one small
unit.
Analog Transmission
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Analog electromagnetic
signals that
continuously vary in
their strength and
speed.
Transmission Flaws
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Noise - unwanted interference from external sources, which can
degrade or distort a signal.
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Attenuation - the loss of a signal’s strength as it travels away from its
source.
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Amplifier - an electronic device that increases the voltage, or power, of
the signals.
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Regeneration - when digital signals are repeated, they are actually
retransmitted in their original, pure form, without any noise.
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Repeater - a device that regenerates a digital signal.
Transmission Flaws
Transmission Flaws
Encoding and the Numbering
System
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Encoding - the process of modifying data so
that it can be interpreted by the receiver.
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Methods for encoding data include:
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The Decimal System
The Binary System
Hexadecimal System
EBCDIC
ASCII
UNICODE
Measuring Data
Throughput and Bandwidth
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Throughput - the amount of data that a
communications channel can carry during a
given period of time.
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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.
Summary
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Electricity may exist as either static electricity, the
imbalance of charges, or as current electricity, the flow of
charge along a conductor.
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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.
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Electronic devices may be active or passive. Examples of
passive devices are capacitors and inductors. Examples
of active devices are transistors and diodes.