# Pulse Code Modulation Viva Questions

Pulse Code Modulation:

1. What is PCM? Does PCM come under Digital Modulation technique?
2. What are the applications of PCM?
3. What is the need for Regenerative repeaters in PCM?
4. Draw the block diagram of PCM system.
5. Define µ-law and A-law. And draw the characteristics of two laws.
6. What is meant by Quantization?
7. Differentiate Uniform and Non uniform Quantization techniques.
8. What is meant by companding in PCM?
10. What is the difference between ADC & PCM?
13. What is slope overload distortion?
14. Draw the waveforms of PCM modulation and demodulation.
15. State sampling theorem.
16. What is aliasing?
17. Give the expression for aliasing error and the bound for aliasing error.
18. What is quantization?
19. What are the various steps involved in A/D conversion.
20. Define step size.
21. What is the importance of regenerative repeater?
22. List out the three basic functions of regenerative repeater.
23. What is companding?
24. Write the mean square quantization error if the step size is S.
25. What is a mid tread Quantizer?
26. What is a mid rise Quantizer?
27. What do you mean by quantizing process?
28. What will happen when sampling rate is greater than Nyquist rate?
29. What will happen when sampling rate is less than Nyquist rate?
30. Find the A/D Converter output for input DC voltage of 3.6V.
31. In digital telephony, (a) what kind of modulation is used? (b)Give the typical sampling rate, output data rate and speech signal Bandwidth.
32. Mention some applications of PCM.
33. What is the function of Sample and Hold circuit?
34. Write the expression for SNR in decibels of a PCM system.
35. For a DAC the required resolution is 25mv and the total input is 5V. the number of bits required would be——————————————.

## Author: Lakshmi Prasanna Ponnala

Completed M.Tech in Digital Electronics and Communication Systems.

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