Frequency Hopping

Digital Communications Systems

This set of Digital Communications Multiple Choice Questions & Answers (MCQs) focuses on “Direct sequence and frequency hopping”.

1. DS/BPSK includes
a) Despreading
b) Demodulation
c) Despreading & Demodulation
d) None of the mentioned

2. In direct sequence process which step is performed first?
a) De-spreading
b) Demodulation
c) Despreading & Demodulation
d) None of the mentioned

3. The processing gain is given as
a) Wss/R
b) R/Wss
c) Wss/2R
d) R/2Wss

4. Chip is defined as
a) Shortest uninterrupted waveform
b) Largest uninterrupted waveform
c) Shortest diversion
d) None of the mentioned

5. Processing gain is given as
a) Wss/R
b) Rch/R
c) Wss/R & Rch/R
d) None of the mentioned

6. Which modulation scheme is preferred for direct sequence spread spectrum process?
a) BPSK
b) QPSK
c) BPSK & QPSK
d) None of the mentioned

7. The frequency hopping system uses ______ modulation scheme.
a) FSK
b) BPSK
c) MFSK
d) MPSK

8. The minimum spacing between consecutive hop positions gives the
a) Minimum number of chips necessary
b) Maximum number of chips necessary
c) Chip rate
d) None of the mentioned

9. Which system allows larger processing gain?
a) Direct sequence
b) Frequency hopping
c) Direct sequence & Frequency hopping
d) None of the mentioned

10. In which technique is phase coherence hard to maintain?
a) Direct sequence
b) Frequency hopping
c) Direct sequence & Frequency hopping
d) None of the mentioned

11. Which type of demodulator is used in the frequency hopping technique?
a) Coherent
b) Non coherent
c) Coherent & Non coherent
d) None of the mentioned

12. Robustness gives the inability of a signal to withstand the impairments.
a) True
b) False

13. Chips are the
a) Repeated symbols
b) Non repeated symbols
c) Smallest length symbols
d) None of the mentioned

14. Slow frequency hopping is
a) Several hops per modulation
b) Several modulations per hop
c) Several symbols per modulation
d) None of the mentioned

15. Fast frequency hopping is
a) Several modulations per hop
b) Several modulations per symbol
c) Several symbols per modulation
d) None of the mentioned

16. Which duration is shorter?
a) Hop duration
b) Symbol duration
c) Chip duration
d) None of the mentioned

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