Digital Modulation

Wireless & Mobile Communications

This set of Wireless & Mobile Communications Multiple Choice Questions & Answers (MCQs) focuses on “Digital Modulation”.

1. Modern mobile communication systems use analog modulation techniques.
a) True
b) False

2. Which of the following is not an advantage of digital modulation?
a) Greater noise immunity
b) Greater security
c) Easier multiplexing
d) Less bandwidth requirement

3. A desirable modulation scheme provides _________ bit error rates at __________ received signal to noise ratios.
a) Low, low
b) Low, high
c) High, high
d) High, low

4. The performance of modulation scheme is not measured in terms of __________
a) Power efficiency
b) Bandwidth efficiency
c) Cost and complexity
d) Transmitted power

5. In digital communication system, in order to increase noise immunity, it is necessary to increase _________
a) Signal power
b) Signal amplitude
c) Signal frequency
d) Signal magnitude

6. Which of the following is the ratio of signal energy per bit to noise power spectral density?
a) Bandwidth efficiency
b) Spectral density
c) Power efficiency
d) Power density

7. Increasing the data rate implies the increase in pulse width of digital symbol.
a) True
b) False

8. Which of the following is the ratio of the throughput data rate per Hertz?
a) Bandwidth efficiency
b) Spectral density
c) Power efficiency
d) Power density

9. Which of the following is defined as the range of frequencies over which the signal has a non zero power spectral density?
a) Null to null bandwidth
b) Half power bandwidth
c) 3 dB bandwidth
d) Absolute bandwidth
.

10. _______ is equal to width of main spectral lobe.
a) Null to null bandwidth
b) Half power bandwidth
c) 3 dB bandwidth
d) Absolute bandwidth

11. Half power bandwidth is also called ______
a) Absolute bandwidth
b) Null to null bandwidth
c) 3 dB bandwidth
d) Zero dB bandwidth

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