Direct-Sequence MCQ [Free PDF] – Objective Question Answer for Direct-Sequence in Digital Communication Quiz

1. DS/BPSK includes

A. Despreading
B. Demodulation
C. Despreading & Demodulation
D. None of the mentioned

Answer: C

DS/BPSK is a two-step process that includes despreading and demodulation.

 

2. In the direct sequence process which step is performed first?

A. De-spreading
B. Demodulation
C. Despreading & Demodulation
D. None of the mentioned

Answer: A

In the direct sequence process, the De-spreading correlator is followed by a modulator.

 

3. The processing gain is given as

A. Wss/R
B. R/Wss
C. Wss/2R
D. R/2Wss

Answer: A

The processing gain is given by the ratio of the minimum bandwidth of the data to the data rate.

 

4. Chip is defined as

A. Shortest uninterrupted waveform
B. Largest uninterrupted waveform
C. Shortest diversion
D. None of the mentioned

Answer: A

A chip is defined as the shortest uninterrupted waveform in the system.

 

5. Processing gain is given as

A. Wss/R
B. Rch/R
C. Wss/R & Rch/R
D. None of the mentioned

Answer: C

Processing gain is given both as the ratio of the minimum bandwidth of the data to data rate and also by the ratio of code chip rate and data rate as minimum bandwidth is approximately equal to code chip rate.

 

6. Which modulation scheme is preferred for the direct sequence spread spectrum process?

A. BPSK
B. QPSK
C. BPSK & QPSK
D. None of the mentioned

Answer: C

Both the modulation scheme BPSK and QPSK can be used for the direct sequence spread spectrum process.

 

7. The frequency hopping system uses a ______ modulation scheme.

A. FSK
B. BPSK
C. MFSK
D. MPSK

Answer: C

The frequency-hopping spread spectrum system uses an M-ary frequency-shift keying modulation scheme.

 

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

Answer: A

The minimum spacing between consecutive hop positions gives the minimum number of chips necessary in the frequency word.

 

9. Which system allows larger processing gain?

A. Direct sequence
B. Frequency hopping
C. Direct sequence & Frequency hopping
D. None of the mentioned

Answer: B

The frequency-hopping spread spectrum system allows greater processing gain than the direct sequence spread spectrum technique.

 

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

Answer: B

In the frequency-hopping spread spectrum phase, coherence is hard to maintain from hop to hop.

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