Digital Communication Multiple Choice Questions and Answers

11. In PCM, the parameter varied in accordance with the amplitude of the modulating signal is

1. Frequency
2. Phase
3. Amplitude
4. None of the above

12. The error probability of a PCM is

1. Gaussian noise + error component due to inter symbol interference
2. Calculated using power spectral density
3. Calculated using noise and inter symbol interference
4. All of the above

13. In Delta Modulation, the bit rate is

1. N times the modulating frequency
2. N times the nyquist criteria
3. N times the sampling frequency
4. None of the above

14. DPCM is a technique

1. Where difference between successive samples of the analog signals are encoded into n-bit data streams
2. Where digital codes are the quantized values of the predicted value
3. To convert analog signal into digital signal
4. All of the above

15. Granular noise occurs when

1. Step size is too large
2. There is interference from the adjacent channel
3. Step size is too small
4. Bandwidth is too large

16. The digital modulation technique in which the step size is varied according to the variation in the slope of the input is called

1. PCM
2. Adaptive delta modulation
3. Delta modulation
4. PAM

17. In Adaptive Delta Modulation, the slope error reduces and

1. Quantization error increases
2. Quantization error remains same
3. Quantization error decreases
4. None of the above

18. Matched filters may be used

1. In parameter estimation problems
2. To estimate the distance of the object
3. To estimate the frequency of the received signal
4. All of the above

19. Information rate is defined as

1. Average number of bits of information per second
2. rH
3. Information per unit time
4. All of the above

20. Entropy is

1. Information in a signal
2. Amplitude of signal
3. Average information per message
4. All of the above