ece7 review presentation#7 chapter 6

8/18/2019 Ece7 Review Presentation#7 Chapter 6

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SINGLE – SIDEBAND

COMMUNICATIONS SYSTEMS

CHAPTER 6


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A form of amplitude

modulation in which thecarrier is transmitted at full

power but only one of the

sidebands is transmitted.

AM Single-sideband FullCarrier

( SSBFC )


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A form of amplitude

modulation in which thecarrier is totally suppressed

and one of the sidebands

removed.

AM Single-sidebandSuppressed Carrier

( SSBSC )


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A form of amplitude modulation

in which one sideband is totally

removed and the carrier voltage

is reduced to approximately

10% of its unmodulatedamplitude.

AM Single-sidebandReduced Carrier

( SSBRC )


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It is the reinserted carrier inSSB! for demodulation

purposes.

Pilot Carrier


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A form of amplitude

modulation in which a singlecarrier fre"uency is

independently modulated by

two different modulating

signals.

AM Independent Sideband

( ISB )


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A form of amplitude

modulation in which thecarrier and one complete

sideband are transmitted# butonly part of the second

sideband is transmitted.

AM Vestigial Sideband

( VSB )


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$$$$ is the picture portion of

a commercial television

broadcasting signal.

VSB System


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Advantages of singlesideband

suppressed and reducedcarrier transmission over

conventional double sideband

fullcarrier transmission.

Bandidt! Conser"ation

and Poer #$$iciency


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&his ratio determines thedegree of intelligibility of a

received signal.

Signal-to-%oise Ratio


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'ith doublesideband

transmission# the two sidebandsand carrier may propagate

through the transmission media

by different paths and therefore#

experience different transmission

impairments.

Selecti"e Fading


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Sideband Fading

A condition in double

sideband transmission where

one sideband is significantly

attenuated.


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A form of selective fading where

there is a reduction of thecarrier level of a 100%

modulated wave that will ma(e

the carrier voltage less than the

vector sum of the two

sidebands.

Carrier-Amplitude Fading


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A condition where the relative

positions of the carrier andsideband vectors of the received

signal change# causing a decided

change in the shape of theenvelope# causing a severely

distorted demodulated signal.Carrier or Sideband

P!ase S!i$t


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A product modulator where the

output signal is the product ofthe modulating signal and the

carrier.

AM Modulator


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)odulator circuits that

inherently remove the carrierduring the modulation

process.

&SBSC Modulators


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A circuit that produces adoublesideband suppressed

carrier signal.

Balanced Modulator


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A balanced modulator that is

constructed with diodes andtransformers. Sometimes

called balanced latticemodulator.

Balanced Ring Modulator


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&he small carrier componentthat is always present in the

output signal of a balanced

modulator.

Carrier 'ea


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&he operation of this balanced

modulator as the balanced ring

modulator# is completely

dependent on the switching

action of diodes *1 through *+under the influence of the carrier

and modulating signal voltages.Balanced Bridge

Modulator


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A doublebalanced

modulator,demodulator thatproduces an output signal that

is proportional to the productof its input signals.

'M*+, .+/

Balanced Modulator IC


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&he circuit where the carrier isreinserted.

'inear Summer


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&hree methods for singlesideband generation.

Filter0 P!ase-S!i$t0 and

1!ird Met!od


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&ypes of singlesideband

filters.

Crystal 'attice0

Ceramic0

Mec!anical0

Sa Filters


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Mec!anical Filter

A mechanically resonant

transducer that receiveselectrical energy# converts it to

mechanical vibrations# and thenconverts the vibrations bac( to

electrical energy at its output.


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-ilters that use acoustic

energy rather than electromechanical energy to provide

excellent performance forprecise bandpass filtering.

Sur$ace Acoustic 2a"e

Filters


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eflected energy that cancelsand attenuates the incident

wave energy.

&estructi"e Inter$erence


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eflected energy that aids the

incident wave energy.

Constructi"e Inter$erence


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A transducer which launchesthe acoustic wave in only one

direction.

3nidirectional

1ransducer


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Any difference between the

transmit and receive localoscillator fre"uencies

produces a $$$$$$$ in thedemodulated information

signal.

Fre4uency 5$$set #rror


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-ifty hert or more offset is

distinguishable by a normallistener as a $$$$$$$.

1onal Variation


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A narrowband / that trac(s the

pilot carrier in the compositeSSB! receiver signal and uses

the recovered carrier to generate

coherent local oscillatorfre"uencies in the synthesier.

Carrier Reco"ery Circuit


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An SSB receiver that uses a

/ carrier recovery circuitand a fre"uency synthesier

to produce coherent local andbeat fre"uency oscillator

fre"uencies.

Multic!annel Pilto Carrier


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Systems that provide narrowband

voice communications for land

mobile services with nearly the

"uality achieved with -) systems

and do it using less than onethirdthe bandwidth.

Amplitude-CompandoringSingle-Sideband

( ACSSB )


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&he process of combining

transmissions from more thanone source and transmitting

them over a common facility#

such as metallic or optical fiber

cable or a radiofre"uency

channel.

Multiple6ing


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Single-SidebandSuppressed-Carrier

1ransmission

A transmission that can be used to

combine hundreds or even

thousands of narrowband channels

into single# composite wideband

channel without the channelsinterfering with each other.


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Singlesideband transmitters

are rated in $$$$$$$$ and $$$$$$$$.

Pea #n"elope Poer

( P#P ) 7Pea #n"elope Voltage

( P#V )

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