Digital Communications Systems

This set of Digital Communication Question Bank focuses on “PAM, PWM and TDM”

1. Flat top sampling of low pass signals
a) Gives rise to aperture effect
b) Implies over sampling
c) Leads to aliasing
d) Introduces delay distortion

2. In a delta modulation system, granular noise occurs when the
a) Modulating signal increases rapidly
b) Pulse rate decreases
c) Pulse amplitude decreases
d) Modulating signal remains constant

3. A PAM signal can be detected using
a) Low pass filter
b) High pass filter
c) Band pass filter
d) All pass filter

4. Coherent demodulation of FSK signal can be performed using
a) Matched filter
b) BPF and envelope detectors
c) Discriminator
d) None of the mentioned

5. The use of non uniform quantization leads to
a) Reduction in transmission bandwidth
b) Increase in maximum SNR
c) Increase in SNR for low level signals
d) Simplification of quantization process

6. Which of the following requires a synchronizing signal?
a) Single channel PPM system
b) PAM
c) DM
d) All of the mentioned

7. A PWM signal can be generated by
a) An astable multi vibrator
b) A monostable multi vibrator
c) Integrating a PPM signal
d) Differentiating a PPM signal

8. TDM is less immune to cross-talk in channel than FDM.
a) True
b) False

9. In an ideal TDM system, the cross correlation between two users of the system is
a) 1
b) 0
c) Infinity
d) -1

10. TDM requires
a) Constant data transmission
b) Transmission of data samples
c) Transmission of data at random
d) Transmission of data of only one measured

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