Transcript ch 02 Principles of Telecommunications Technology

Principles of
Telecommunications
Technology
Chapter 2
Objectives
In this chapter, you will:

Describe the principles of electricity that underlie all
telecommunications signaling
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Explain the concepts of current and voltage as they apply to
telecommunications technology
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Describe the components on an integrated circuit
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Explain the difference between analog and digital transmission
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Use binary encoding to represent decimal numbers
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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.

Electrons - orbit the center of an atom and carry a negative charge
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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.
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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.
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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.
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Electric Current
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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.
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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
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Direct current (DC)
- an electrical charge
flows steadily in one
direction over the
conductor.
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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.
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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.
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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
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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
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Diodes
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Diodes
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Transistors
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Integrated Circuits
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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
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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.
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Transmission Flaws
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Transmission Flaws
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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
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Measuring Data
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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.
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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.
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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.
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Telecommunications
Principles
END
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