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EST (Electronics System and Technologies) > Single-Sideband communications systems (Chapter 6) > Flashcards

Single-Sideband communications systems (Chapter 6) Flashcards

1
Q

AM Double-Sideband Communications Systems have two inherent disadvantages:

A
  1. Carrier power constitutes two-thirds or more of the total transmitted power
  2. it utilizes twice as much bandwidth needed with single-sideband systems
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2
Q

Single sideband was mathematically recognized and understood as early as _____

A

1914

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3
Q

Single sideband during _____ was the patent granted and a successful communications link established between _____ and _____

A

1923
England
United States

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4
Q

A form of amplitude modulation
in which the carrier is transmitted at full power but only one of the
sidebands is transmitted.

A

AM Single-sideband Full Carrier

SSBFC

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5
Q

SSBFC transmissions require only ____ as much bandwidth as conventional double-sideband AM.

A

1/2 or half

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6
Q

In SSBFC, with 100% modulation, the carrier power (Pc) constitutes _____ of the total power transmitted (Pt) and only _____ of the total power is in the sideband.

A

80% or four-fifths

20% or one-fifths

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7
Q

For conventional double-sideband AM with 100% modulation, ____ of the total transmitted power is in the carrier and, _____ is in the sidebands.

A

67% or two-thirds

33% or one-third

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8
Q

SSBFC requires less bandwidth than DSBFC. True or False?

A

True

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9
Q

When the bandwidth is halved, what happens to the total noise power?

A

the noise power is halved

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10
Q

With SSBFC, the repetition rate of the envelope is ____ to the frequency of the modulating signal.

A

equal

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11
Q

With SSBFC, the depth of modulation is _____ to the amplitude of the modulating signal.

A

directly proportional

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12
Q

A form of amplitude modulation

in which the carrier is totally suppressed and one of the sidebands removed.

A

AM Single-sideband Suppressed

Carrier ( SSBSC )

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13
Q

SSBSC transmissions require only ____ as much bandwidth as conventional double-sideband AM.

A

half

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14
Q

In SSBSC with 100% modulation, the sideband power makes up to ____ of the total transmitted power

A

100%

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15
Q

A form of amplitude modulation
in which one sideband is totally removed and the carrier voltage is reduced
to approximately 10% of its unmodulated amplitude. Sometimes called
single-sideband reinserted carrier.

A

AM Single-sideband Reduced

Carrier ( SSBRC )

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16
Q

In SSBRC, _____ of the total power transmitted is in the unsuppressed sideband.

A

96%

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17
Q

To produce a reduced carrier component, the carrier is ______ during modulation and then ______ at a reduced amplitude.

A

totally suppressed

reinserted

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18
Q

SSBRC is often called as _____

A

single-sideband reinserted carrier

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19
Q

reinserted carrier is often called a ______ and is reinserted for demodulation purposes

A

pilot carrier

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20
Q

To demodulate a reduced carrier waveform with a conventional peak detector, the carrier must be ______, _______ and then ______ at a higher level in the receiver.

A

separated, amplified, reinserted

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21
Q

reduced carrier transmission is sometimes called ______

A

exalted carrier

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21
Q

Consequently, the signal-to-noise ratios for single and double sideband are ______

A

the same

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22
Q

In SSBRC, the carrier is transmitted at a ______ ,which also conserves power

A

reduced level

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23
Q

A form of amplitude modulation
in which a single carrier frequency is independently modulated by two
different modulating signals.

A

AM Independent Sideband ( ISB )

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24
Q

It is a form of double-sideband transmission in which the transmitter consists of two independent single-sideband suppressed carrier modulators

A

ISB (Independent Sideband)

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25
Q

ISB conserves both ______ and ______, as two information sources are transmitted within the same frequency spectrum, as would be required by a single source using conventional double- sideband transmission.

A

transmit power

bandwidth

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26
Q

A form of amplitude modulation
in which the carrier and one complete sideband are transmitted, but only part
of the second sideband is transmitted.

A

AM Vestigial Sideband ( VSB )

27
Q

In VSB, the lower modulating-frequencies are transmitted _____, and the higher modulating-frequencies are transmitted _____

A

double-sideband

single-sideband

28
Q

_____ system is the picture portion of a commercial television broadcasting signal, which is designated A5C by the FCC

A

VSB

29
Q

It determines the degree of intelligibility of a received signal

A

signal-to-noise ratio

30
Q

The three common AM transmissions systems:

A

Double-sideband full carrier (DSBFC)
Double-sideband suppressed carrier (DSBSC)
Single-sideband suppressed carrier (SSBSC)

31
Q

the repetition rate of the DSBFC envelop is ______ to the modulating signal frequency

A

equal

32
Q

The repetition rate of the DSBSC envelope is ______ the modulating signal frequency

A

equal to twice

33
Q

The SSBSC waveform forms an envelope. True or false?

A

False

it is not a waveform but rather a single-frequency sinusoid equal in frequency to the unsuppressed sideband frequency

34
Q

A conventional AM wave with 100% modulation contains ____ unit of carrier power and ____ unit of power in each sidebands for a total transmitted peak power of 1.5 units

A

1

0.25

35
Q

A single sideband transmitter rated at ___ unit of power will produce a the same S/N ratio at the output of a receiver as ___ units of carrier plus sideband power from a double-sideband full-carrier signal

A
  1. 5

1. 5

36
Q

Advantages of Single-Sideband transmission

A

Power conservation
Bandwidth conservation
Selective fading
Noise reduction

37
Q

Disadvantages of Single-sideband transmission

A

Complex receiver

Tuning difficulties

38
Q

With double-sideband
transmission, the two sidebands and carrier may propagate through the
transmission media by different paths and therefore, experience different
transmission impairments. This condition is called

A

Selective Fading

39
Q

A condition in double-sideband

transmission where one sideband is significantly attenuated.

A

Sideband Fading

40
Q

The most common and most serious form of selective fading
A condition where the relative
positions of the carrier and sideband vectors of the received signal change,
causing a decided change in the shape of the envelope, causing a severely
distorted demodulated signal.

A

carrier-amplitude fading

41
Q

A product modulator where the

output signal is the product of the modulating signal and the carrier.

A

AM Modulator

42
Q

Modulator circuits that

inherently remove the carrier during the modulation process.

A

DSBSC Modulators

43
Q

A circuit that produces a

double-sideband suppressed-carrier signal.

A

Balanced Modulator

44
Q

A balanced modulator that is
constructed with diodes and transformers. Sometimes called balanced lattice
modulator.

A

Balanced Ring Modulator

45
Q

The small carrier component

that is always present in the output signal of a balanced modulator.

A

Carrier Leak

46
Q

The operation of this balanced
modulator as the balanced ring modulator is completely dependent on the
switching action of diodes D1 through D4 under the influence of the carrier
and modulating signal voltages.

A

Balanced Bridge Modulator

47
Q

A double-balanced
modulator/demodulator that produces an output signal that is proportional to
the product of its input signals.

A

LM1497 / 1596 Balanced

Modulator IC

48
Q

The circuit where the carrier

is reinserted.

A

Linear Summer

49
Q

Three methods for

single-sideband generation.

A

Filter, Phase-Shift, and Third

Method

50
Q

Types of single-sideband

filters.

A

Crystal Lattice, Ceramic,

Mechanical, Saw Filters

51
Q

A mechanically resonant
transducer that receives electrical energy, converts it to mechanical
vibrations, and then converts the vibrations back to electrical energy at its
output.

A

Mechanical Filter

52
Q

Filters that use acoustic
energy rather than electro-mechanical energy to provide excellent performance
for precise bandpass filtering.

A

Surface Acoustic Wave Filters

53
Q

Reflected energy that cancels

and attenuates the incident wave energy.

A

Heterodyne

54
Q

Reflected energy that aids the

incident wave energy.

A

Constructive Interference

55
Q

A transducer which launches the

acoustic wave in only one direction.

A

Unidirectional Transducer

56
Q

Any difference between the
transmit and receive local oscillator frequencies produces a _______ in the
demodulated information signal.

A

frequency offset error

57
Q

Fifty hertz or more offset is

distinguishable by a normal listener as a _______.

A

tonal variation

58
Q

A narrowband PLL that tracks
the pilot carrier in the composite SSBRC receiver signal and uses the
recovered carrier to generate coherent local oscillator frequencies in the
synthesizer.

A

Carrier Recovery Circuit

59
Q

An SSB receiver that uses a PLL
carrier recovery circuit and a frequency synthesizer to produce coherent
local and beat frequency oscillator frequencies.

A

Multichannel Pilot Carrier

60
Q

Systems that provide narrowband
voice communications for land-mobile services with nearly the quality
achieved with FM systems and do it using less than one-third the bandwidth.

A

Amplitude-Compandoring Single-Sideband

ACSSB

61
Q

It is the process of combining transmissions from more than one source and transmitting them over a common facility, such as metallic or optical fiber cable or a radio frequency channel

A

Frequency-Division Multiplexing (FDM)

62
Q

It is a multiplexing method that uses double-sideband suppressed-carrier transmission to combine two information sources into a single composite waveform that is then transmitted over a common facility without the two channels interfering with each other

A

Quadrature Multiplexing (QM)

63
Q

A transmission that can be used
to combine hundreds or even thousands of narrowband channels into single,
composite wideband channel without the channels interfering with each other.

A

Single-Sideband

Suppressed-Carrier Transmission

64
Q

Single-sideband transmitters

are rated in ________ and ________.

A

Peak Envelope Power ( PEP )

& Peak Envelope Voltage ( PEV )

EST (Electronics System and Technologies) (4 decks)

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