This set of Analog Communications Multiple Choice Questions & Answers (MCQs) focuses on “Phase Shift Method”.
1. Which of the following is an indirect way of generating frequency modulated signals?
a) Armstrong modulator
b) Varacter diode modulator
c) Reactance FET modulator
d) Reactance bipolar transistor modulator
Explanation: The indirect way of generating frequency modulated signals was first proposed by Armstrong. A frequency modulator so designed is named as Armstrong modulator.
2. Which of the following determines carrier deviation in frequency modulation?
a) modulating voltage
d) either frequency or amplitude
Explanation: In frequency modulation, frequency of carrier varies with the modulating voltage. In frequency modulation, it is modulating voltage that is responsible for deviation of carrier.
3. Balance modulator is used to produce __________
Explanation: A balance modulator mixes audio signal and radio frequency carrier, but suppresses the carrier, leaving only sidebands. Double side band is usually produced by balance modulator.
4. Full AM signal is preferred over SSB in broadcasting purpose because ________
a) generation of full AM is easier
b) detection of full AM is simpler
c) requires large bandwidth
d) for both detection and generation of full AM
Explanation: SSB is preferred because of its low bandwidth. It reduces its bandwidth by removing one of two bands since both bands are exactly same and carries same information. But full amplitude modulation is sometimes preferred over it because in it detection of full AM is simpler.
5. Which among the following is not necessarily the advantage of SSB over AM?
a) required bandwidth for SSB is low
b) less power handled
c) complex circuit
d) simple circuit
Explanation: SSB is preferred because of its low bandwidth. It reduces its bandwidth by removing one of two bands since both bands are exactly same and carries same information. It has many more advantage over AM but it has not simple circuit.
6. Which filter is used to get back the original signal from sampled signal?
a) low pass filter
b) high pass filter
c) band pass filter
d) band reject filter
Explanation: Sampling is the conversion of continuous-time signal to discrete-time signal. Now to get back the original signal we have to use low pass filter.
7. Carson’s rule is used to ________
a) calculate Bandwidth of FM signal
b) calculate SNR
c) calculate Modulation index
d) calculate Figure of merit
Explanation: According to Carson’s rule, the required bandwidth is twice the sum of the maximum frequency deviation and the maximum modulating signal frequency or B = 2(fd +fm)Hz.
8. FM signals can be generated by using ________
a) Varacter diode
b) Laser diode
c) Backward diode
d) Gunn diode
Explanation: Varacter diode or tuning diode that has a variable capacitance. It is operated as reverse-biased and therefore no current flows. It is mainly used for generation of FM signals only.
9. Granular noise occurs in Delta Modulation, when ____________
a) pulse rate decreases
b) pulse amplitude decreases
c) modulating signal increases
d) modulating signal remains constant
Explanation: Delta modulation is used for transmission of voice information where quality is not the primarily importance. Its drawback is it has two noises namely slope overload and granular noise. So for getting rid from these noises we use ADM (Adaptive Delta Modulation).
10. DM stands for ________
a) Density Modulation
b) Delta Modulation
c) Doubling Modulation
d) Delta Medium
Explanation: DM stands for Delta Modulation. Delta modulation is used for transmission of voice information where quality is not the primarily importance.
Sanfoundry Global Education & Learning Series – Analog Communications.
To practice all areas of Analog Communications, here is complete set of 1000+ Multiple Choice Questions and Answers.