MILLER | CHAP 4,5,6

An SSB signal with a maximum level of 200 V p-p into a 50 load results in a PEP rating of

a. 200 W

b. 50 W

c. 100 W

d. 800 W

c

State the chief advantage(s) of a standard SSB system.

a. Maximum signal range with minimum transmitted power

b. Easy carrier reinsertion

c. Elimination of carrier interference

d. a and c

d

The noise advantage of SSB over AM is

a. 3-5 dB

b. 5-7 dB

c. 8-10 dB

d. 10-12 dB

d

What is the difference between a balanced modulator and a regular modulator?

a. There is no carrier produced in the output of a balanced modulator.

b. In a balanced modulator, there is 180º phase shift between the upper and lower sidebands.

c. In a balanced modulator, only one sideband is produced.

d. In a balanced modulator, harmonics of the sidebands are suppressed.

a

In a balanced-ring modulator, the carrier suppression is accomplished by

a. A dual-gate FET having symmetry

b. Center-tapped transformers causing canceling magnetic fields

c. The nonlinearity of the diodes that are used

d. Symmetrical differential amplifier stages

b

Which cannot be used successfully to convert DSB-SC to SSB?

a. Crystal filter

b. Ceramic filter

c. Mechanical filter

d. Tank circuit

d

Another term for ripple amplitude for a ceramic filter is

a. The shape factor

b. The peak-to-valley ratio

c. The insertion loss

d. The quality factor

b

Which of the following is not an advantage of the phase method over the filter method in producing SSB?

a. The design of the 90º phase-shift network for the intelligence frequencies is simple.

b. Lower intelligence frequencies can be economically used, because a high-Q filter is not necessary.

c. Intermediate balanced modulators are not necessary, because high-Q filters are not needed.

d. It is easier to switch from one sideband to the other.

a

Once an SSB signal has been generated, it must be amplified by

a. A nonlinear amplifier to conserve bandwidth

b. A nonlinear amplifier to conserve energy

c. A linear amplifier to conserve bandwidth

d. A linear amplifier to avoid distortion

d

The advantages provided by carrier elimination in SSB do not apply to transmission of

a. Code

b. Music

c. Noise

d. All the above

b

Provide the approximate "outside-of-passband" attenuation of a Butterworth filter.

a. 3-dB slope per octave

b. 3-dB slope per decade

c. 6-dB slope per octave

d. 6-dB slope per decade

c

An SSB receiver recreates the original intelligence signal by

a. Mixing the USB with LSB signals and filtering out the resulting different frequencies

b. Filtering out the difference between either sideband and the internally generated carrier signal

c. Filtering out the harmonics of the received sideband signal frequencies

d. Amplifying the dc term produced by mixing action

b

Common types of balanced modulators include

a. Ring modulator

b. Phase modulator

c. Lattice modulator

d. All the above

a

14. Describe the oscilloscope waveform of an SSB transmitter's balanced modulator if it exhibits carrier leak-through.

a. Trapezoidal wave

b. Sinewave

c. FM wave

d. AM wave

d

The two-tone test is used to

a. Test carrier suppression

b. Test filter ripple

c. Test amplifier linearity

d. None of the above

c

Angle modulation includes the following types of modulation:

a. FM

b. PM

c. AM

d. All the above

e. a and b

e

The amount of frequency increase and decrease around the center frequency in an FM signal is called the

a. Index of modulation

b. Frequency deviation

c. Phase deviation

d. Bandwidth of the FM signal

b

The amount of frequency deviation is dependent on the intelligence frequency in

a. An FM signal

b. A PM signal

c. Both FM and PM signals

d. Neither FM nor PM signals

b

An FM signal has an intelligence frequency of 2 kHz and a maximum deviation of 10 kHz. If its carrier frequency is set at 162.4 Mhz, what is its index of modulation?

a. 10

b. 5

c. 2

d. 20

b

The amount an FM carrier frequency deviates for a given modulating input voltage level is called the

a. Frequency deviation

b. Index of modulation

c. Deviation constant

d. Deviation ratio

b

Standard FM broadcast stations use a maximum bandwidth of

a. 150 kHz

b. 200 kHz

c. 75 kHz

d. 15 kHz

b

Carson's rule is used to approximate the necessary

a. Frequency deviation

b. Bandwidth

c. Capture ratio

d. Modulation index

b

An FM transmitter has an output power of 500 W when it is not modulated. When intelligence is added, its modulation index is 2.0. What is its output power with a modulation index of 2.0?

a. 250 W

b. 500 W

c. 1000 W

d. 2000 W

b

Another way to describe the modulation index is using the

a. Deviation ratio

b. Deviation constant

c. Capture ratio

d. Maximum deviation

a

The inherent ability of FM to minimize the effect of undesired signals operating at the same or nearly the same frequency as the desired station is known as the

a. Capture effect

b. Signal-to-noise ratio

c. Noise figure

d. Bessel function

a

In a Crosby FM transmitter, an FM signal having a center frequency of 2.04 Mhz and a deviation of 69 Hz is passed through four cascaded frequency multiplier stages: two triplers, one doubler, and one quadrupler. What type of signal appears at the output of the last multiplier stage?

a. Center frequency of 2.04 Mhz and deviation of 4.96 kHz

b. Center frequency of 146.88 Mhz and deviation of 4.96 kHz

c. Center frequency of 2.04 Mhz and deviation of 69 Hz

d. Center frequency of 146.88 Mhz and deviation of 69 Hz

b

The circuitry used to increase the operating frequency of a transmitter up to a specified value is called the

a. Multiplier

b. Expander

c. Pump chain

d. All the above

c

The purpose of the matrix network in a stereo FM broadcast transmitter is to

a. Mix the 38-kHz pilot carrier with the L - R audio

b. Convert the L and R channels to L + R and L - R channels

c. Separate the left channel from the right channel

d. Modulate the L + R and L - R signals with the carrier signal

b

An FM signal has an intelligence frequency of 5 kHz and a maximum deviation of 25 kHz. Its index of modulation is

a. 125

b. 0.2

c. 5

d. 6

c

Frequency multipliers

a. Are used to multiply the frequency of the carrier signal of an FM signal

b. Consist of a class C amplifier followed by a tank circuit that filters out a single harmonic

c. Are used to multiply the frequency deviation of an FM signal

d. All the above

d

A difference between AM and FM receiver block diagrams is that the FM version includes a

a. Limiter

b. Discriminator

c. Deemphasis network

d. All the above

d

An FM receiver rarely works satisfactorily without an RF amplifier because

a. FM receivers typically work with smaller input signal levels due to the noise characteristics

b. FM receivers have a narrower bandwidth.

c. FM receivers do not have very much gain in their IF amplifier stages.

d. FM receivers need RF amplifier stages to be able to decode stereo signals.

a

A certain FM receiver provides a voltage gain of 113 dB prior to its limiter. The limiter's quieting voltage is 400 mV. Its sensitivity is approximately a. 2 uV

b. 1 uV

c. 0.9 uV

d. 0.7 uV

c

The use of dual-gate MOSFETs in RF amplifier stages

a. Offers increased dynamic range over those of JFETs

b. Produces higher-frequency responses than do JFETs

c. Produces higher values of voltage gain than do JFETs

d. Is not compatible with AGC

a

The Foster-Seely detector design is superior to the ratio detector in that it

a. Does not respond to any undesired amplitude variations

b. Also provides an output AGC signal

c. Offers superior linear response to wideband FM deviations

d. Does not need a limiter stage

c

Local oscillator reradiation refers to radiation through the

a. Receiver's wiring

b. IF transformer

c. Antenna

d. All the above

c

Which is not one of the three stages in which a PLL can be operated?

a. Free-running

b. Capture

c. Locked/tracking

d. Searching

d

A PLL is set up so that its VCO free-runs at 8.9 Mhz. The VCO does not change frequency unless its input is within 75 kHz of 8.9 Mhz. After it does lock, the input frequency can be adjusted within 120 kHz of 8.9 Mhz without having the PLL start to free-run again. The capture range of the PLL is

a. 75 kHz

b. 120 kHz

c. 150 kHz

d. 240 kHz

c

Slope detection is seldom used due to

a. Nonlinearity

b. Attenuation

c. Complexity

d. All the above

a

In an FM stereo receiver, what is the purpose of the 23-53-kHz filter?

a. To filter out the SCA signal at the output of the discriminator

b. To filter out the L - R signal at the output of the discriminator

c. To filter out the L + R signal at the output of the discriminator

d. To produce separate L and R signals from the L + R and L - signals

b

A dual audio amplifier is rated to provide 65 dB of channel separation. If the right channel has 4 W of output power, how much of this power could be due to the left channel intelligence?

a. 4 W

b. 79 nW

c. 1.26 W

d. 2.25 mW

c

The hold-in range for a PLL concerns the

a. Range of frequencies in which it will remain locked

b. Allowable range of dc voltage

c. Allowable range of ac input voltage

d. Satisfactory range of operating temperatures

a

The input signal into a PLL is at the

a. VCO

b. Low-pass filter

c. Comparator

d. Phase detector

d

The square-law relationship of the FETs input versus output

a. Allows for greater sensitivity in an FM receiver

b. Provides improved noise performance

c. Reduces shot noise

d. Minimizes cross-modulation

d

When troubleshooting a stereo demodulator, the input signal should be about to

a. 10 uV rms

b. 100 uV rms

c. 1 mV rms

d. 100 mV rms

d