This set of Analog Communications Interview Questions and Answers for Experienced people focuses on “Comparision of SSB Suppression Techniques”.
1. What is the expected modulation index in case of wide band FM?
a) less than 1
b) 1
c) 1⁄2
d) more than 1
View Answer
Explanation: For producing Narrow band frequency modulated wave, modulation index should be less than or equal to1. For wideband frequency modulated wave, modulation index should be greater than 1.
2. What is the expected modulation index in case of narrow band FM?
a) less than or equal to 1
b) infinite
c) 1.5
d) more than 1
View Answer
Explanation: For producing Narrow band frequency modulated wave, modulation index should be less than or equal to1. For wideband frequency modulated wave, modulation index should be greater than 1.
3. Which of the following statement is true about pulse position modulation system?
a) pulses have constant width but varying amplitude
b) pulses have constant amplitudes and constant widths
c) pulses have constant amplitude but varying widths
d) pulses have varying width and varying amplitude
View Answer
Explanation: Pulse Position Modulation (PPM) is a type of modulation process in which position of the pulse of the carrier wave is varied with respect to the instantaneous position values of the message signal. In pulse modulation, pulses have constant amplitude and widths.
4. IF stage is a receiver employs ________
a) impedance coupling
b) capacitive coupling
c) single tuned transformer coupling
d) double tuned transformer coupling
View Answer
Explanation: A frequency to which a carrier wave is shifted as an intermediate step is known as Intermediate Frequency. It employs double tuned transformer coupling.
5. In higher power AM transmission, modulation is done at _________
a) Source stage
b) Transducer Stage
c) Oscillator stage
d) RF power stage
View Answer
Explanation: RF power amplifier converts a low power radio frequency signal to high power. Modulation is done at RF power stage for high power AM transmission.
6. If modulation index of an AM was in changed from 0 to 1, then transmitted power ________
a) increases by 100%
b) increases by 50%
c) increases by 75%
d) increases by 25%
View Answer
Explanation: Modulation index indicates amount of modulation in the carrier signal. If modulation index changes to 1 from 0, its transmitted power increases by 50%.
7. In PCM system, output S/N increases ________
a) parabolically with bandwidth
b) exponentially with bandwidth
c) inversely with bandwidth
d) linearly with bandwidth
View Answer
Explanation: Pulse code modulation (PCM) is a digital form of communication. Pulse Code Modulation is a technique in which the amplitude of an analogue signal is converted to a binary value represented as a series of pulses. if we calculate the ratio of signal to noise ratio for different bandwidth then we observe that it increases exponentially with it.
8. Companding is used in PCM transmitters to overcome quantizing noise in PCM.
a) True
b) False
View Answer
Explanation: Companding is the process through which the signal to noise ratio of a wave is reduced by compressing and expanding the signal. It decreases the number of bits required to record the strongest signal. Companding also improves signal to noise ratio.
Sanfoundry Global Education & Learning Series – Analog Communications.
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