Deck 4: Single-Sideband Communications

Question 1

In a push-pull modulator, the carrier suppression is accomplished by:

A) center-tapped transformers causing canceling magnetic fields.
B) the nonlinearity of the diodes that are used.
C) symmetrical differential amplifier stages
D) a dual-gate FET having symmetry.

Answer 1

A

Question 2

Which is not an advantage of SSB over AM?

A) SSB provides a more effective utilization of the available frequency spectrum
B) SSB has a resulting savings in power
C) simplicity in design
D) SSB is less subject to the effects of selective fading

Answer 2

C

Question 3

At 100% modulation, an AM signal has a total power of 1200 watts. If it was converted to SSB and the sideband component had the same amplitude as before, the total power would be:

A) 800 watts
B) 200 watts
C) 100 watts
D) 400 watts

Answer 3

B

Question 4

If the carrier and one of the sidebands are completely eliminated, the resulting signal is referred to as:

A) ACSSB
B) independent sideband
C) vestigial sideband
D) SSBSC

Question 5

Which of the following is NOT an advantage that the phase method of generating has over the filter method?

A) greater ease in switching from one sideband to the other
B) requires high Q filters
C) SSB generated directly at desired transmitting frequency
D) lower intelligence frequencies can be used

Question 6

In a linear integrated circuit balanced modulator such as the LM1496, carrier suppression is accomplished by:

A) the nonlinearity of the diodes that are used
B) a dual-gate FET having symmetry
C) symmetrical differential amplifier stages
D) center-tapped transformers causing canceling magnetic fields

Question 7

The type of sideband that involves having the upper sideband contain different information than the lower sideband is referred to as:

A) SSBSC
B) ACSSB
C) vestigial sideband
D) independent sideband

Question 8

Which of the following is required for SSB transmission?

A) elimination of one sideband
B) A and B
C) carrier elimination
D) none of the above

Question 9

Which of the following can be used as an SSB demodulator?

A) mixer
B) RF amplifier
C) audio amplifier
D) AGC circuitry

Question 10

SSB transmitters are usually rated in terms of:

A) power gain
B) modulation index
C) peak envelope power
D) voltage gain

Question 11

The major disadvantage of the phase method of SSB generation is:

A) does not use high Q filters
B) 90 degree phase-shifting network for intelligence signal
C) requires two balance modulators
D) all of the above

Question 12

The output of a balanced modulator in an SSB transmitter being modulated with a voice intelligence signal is:

A) sinewave at the carrier frequency
B) SSB
C) DSB-SC
D) conventional AM

Question 13

Which of the following will not work as a balanced modulator?

A) a push-pull modulator
B) a ring-diode modulator
C) an LM1496 integrated circuit stage
D) a dual-gate FET and a band-pass filter

Question 14

The most important advantage of SSB over AM is:

A) the resulting savings in power
B) simplicity in design
C) that it is a more effective utilization of the available frequency spectrum
D) that it is less subject to the effects of selective fading

Question 15

A more recently developed system of sideband that involves compressing the amplitude of the intelligence signal before modulation occurs is called:

A) ACSSB
B) vestigial sideband
C) SSBSC
D) independent sideband

Question 16

The type of sideband that is used for NTSC television video transmission is called:

A) independent sideband
B) SSBSC
C) vestigial sideband
D) ACSSB

Question 17

The PEP rating of an SSB transmitter is often misleading due to:

A) the PEP rating is the same rating no matter what type of waveform the transmitter is providing.
B) the fact that with normal voice signals, an SSB transmitter develops an average of only one-third to one-fourth of its PEP rating.
C) the SSB transmitter's power supplies and components are not always designed for continuous duty PEP power levels.
D) all of the above

Question 18

Crystal filters:

A) employ phasing capacitors to produce a rejection notch of undesired resonant frequencies
B) have Q values as high as 50,000
C) employ phasing capacitors to produce a rejection notch of undesired resonant frequencies
D) all of the above

Question 19

In an SSB transmitter having voice modulation using audio frequencies ranging from 100 Hz to 3 kHz, the upper and lower sidebands generated by the balanced modulator are separated by:

A) 40 Hz
B) 200 Hz
C) 6 kHz
D) 500 Hz

Question 20

Voice transmission requires an audio frequency range of:

A) 20 Hz to 20 kHz
B) 100 Hz to 3 kHz
C) 500 Hz to 1 kHz
D) 30 Hz to 10 kHz

Question 21

The signal processor that increases all negative dBm power levels and at the same time decreases all positive dBm power levels is:

A) a signal compressor
B) a signal expander
C) a phase-locked loop
D) a linear amplifier

Question 22

The main disadvantage of the phase method in generating SSB is:

A) the complex design of the 90 degree phase shifting network for the carrier signal
B) the complex method of mixing the carrier with the intelligence signal
C) the complex method used to amplify the resulting SSB signal
D) the complex design of the 90 degree phase shifting network for the intelligence signal

Question 23

Which is the most popular method used to generate SSB in transmitter design?

A) filter method
B) amplitude-compandoring method
C) phase method
D) lattice method

Question 24

Which is not an advantage of ceramic filters over crystal filters?

A) more rugged in construction
B) less expensive
C) smaller in size
D) higher Q values

Question 25

The standard SSB demodulator consists of:

A) a nonlinear diode and a low-pass filter
B) a beat frequency oscillator, nonlinear mixer, and low-pass filter
C) a sharp bandpass filter and an audio amplifier stage
D) an RF amplifier, nonlinear mixer, and IF amplifier stage

Question 26

ACSSB is:

A) a method of compressing the audio before modulation and to expand it following demodulation.
B) a new method of allowing narrow band voice communications with the performance of FM systems for the land-mobile communication industry
C) an acronym for amplitude compandored single-sideband
D) all of the above

Question 27

The ratio of the 60 dB and 6 dB bandwidths for a ceramic filter is known as:

A) the roll-off rate of the skirt
B) the shape factor
C) the ripple amplitude
D) the quality factor

Question 28

The variation in attenuation within the bandpass frequencies of a ceramic filter is called:

A) the shape factor
B) the ripple amplitude
C) the roll-off rate of the s
D) the quality factor

Question 29

The filter consisting of resonant disks, driving rods, bias magnets and transducer coils is the:

A) crystal filter
B) tank circuit
C) ceramic filter
D) mechanical filter

Question 30

In an SSB receiver, if the BFO drifts slightly off of the carrier frequency:

A) the output intelligence amplitude is reduced.
B) the output intelligence is badly distorted.
C) the noise level increases
D) harmonics are produced by mixing action of the nonlinear device

Question 31

The signal processor that decreases all negative dBm power levels and at the same time increases all positive dBm power levels is:

A) a linear amplifier
B) a phase-locked loop
C) a signal compressor
D) a signal expander

Question 32

Which is not a general method used to generate SSB in transmitter design?

A) lattice method
B) amplitude-compandoring method
C) filter method
D) phase method

Question 33

Why is the carrier signal needed in an SSB receiver?

A) It is needed for the demodulator to be able to recreate the intelligence
B) Without a carrier, the signal strength of the received station is zero
C) The carrier actually contains the intelligence signal
D) It is needed for the receiver to maintain its sensitivity and selectivity

Question 34

The first designed sharp filter used in SSB transmitters to produce SSB is the:

A) mechanical filter
B) ceramic filter
C) crystal filter
D) tank circuit