This set of Analog Communications Interview Questions and Answers for freshers focuses on “Representation of SSB-SC in Time & Frequency Domain”.
1. Which device is has more chance to be found in SSB transmitter?
a) tuned modulator
b) class A RF amplifier
c) class C audio amplifier
d) class B RF amplifier
Explanation: By tuning the circuit we ensure that the circuit will for particular frequencies only. In SSB tuned modulator is more likely to found.
2. The RF section of radio consists both oscillator and buffer stage.
Explanation: RF is electromagnetic wave frequencies in the range 3 KHz to 300 GHz. It generally refers to electrical rather than mechanical oscillations.
3. What is the frequency of audio modulation?
a) 1 KHz
b) 2 KHz
c) 3 KHz
d) 4 KHz
Explanation: Frequency of audio modulation is approximately close to 2KHz. It is also said standard frequency for audio modulation.
4. In telegraphy we generally use __________
a) Amplitude modulation
b) Frequency modulation
c) Pulse modulation
d) Vestigial side band modulation
Explanation: In pulse modulation, width or amplitude of pulses is varied. It is mostly used for telegraphy purpose.
5. In FM both the frequency and amplitude of carrier signal is varied in accordance with the instantaneous value of modulating signal.
Explanation: In FM the frequency of carrier signal is varied in accordance with the instantaneous value of modulating signal.
6. In the equation, 20cos(108 t+3 sin109 t) the modulation index is ________
Explanation: On comparing with the general equation Ac cos(2πfc t+kf sin2πfm t) where kf is modulation index. We find that the modulation index for this equation is 3.
7. Antenna can also be used as a receiver.
Explanation: Antennas can be used as transmitter and receiver both. Antenna transmits or receives electromagnetic waves only.
8. What is the advantage of IF modulation?
a) it uses SSB which further reduces its bandwidth
b) modular section and visual exciter can be of any state
c) it cannot be tuned
d) modular section and visual exciter can be solid state devices
Explanation: Advantages of IF modulation is that the modular section and visual exciter can be solid state devices. Its other advantages are it can use VSB filter that can be introduced at low power level. Moreover it is economical.
9. We can use either cone type or horn type loudspeakers in tape recorders.
Explanation: In tape recorders only cone type loudspeakers can be used. It not works well with the horn type loudspeakers.
10. The advantage of using mechanical filter in filter system of sideband suppression is good attenuation characteristics.
Explanation: The advantage of using mechanical filter in filter system of sideband suppression is smaller size, good band pass, good attenuation characteristics.
Sanfoundry Global Education & Learning Series – Analog Communications.
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