Digital Communication Multiple Choice Questions and Answers for Practice

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

21. Timing jitter is

1. Change in frequency
2. Deviation in location of the pulses
3. Change in amplitude
4. All of the above

22. A linear code

1. All-zero code word is a code word
2. Minimum hamming distance between two code words is equal to weight of any non zero code word
3. Sum of code words is also a code word
4. All of the above

23. Parity bit coding may not be used for

1. Which bit is in error
2. Both a & b
3. Error in more than single bit
4. None of the above

24. Parity check bit coding is used for

1. Error detection
2. Error correction and detection
3. Error correction
4. None of the above

25. Run Length Encoding is used for

1. Bit error correction
2. Correction of error in multiple bits
3. Reducing the repeated string of characters
4. All of the above

26. The number of bits of data transmitted per second is called

1. Modulation rate
2. Coding
3. Data signaling rate
4. None of the above

27. Pulse shaping is done

1. by limiting the bandwidth of transmission
2. after line coding and modulation of signal
3. to control Inter Symbol Interference
4. All of the above

28. Nyquist criterion helps in

1. Reduction in transmission bandwidth
2. Increase in transmission bandwidth
3. Transmitting the signal without ISI
4. Both a and b

29. The Nyquist theorem is

1. Helps in quantization
2. Limits the bandwidth requirement
3. Relates the conditions in time domain and frequency domain
4. Both a and c

30. ASK modulated signal has the bandwidth

1. Half the bandwidth of baseband signal
2. Double the bandwidth of baseband signal
3. Same as the bandwidth of baseband signal
4. None of the above