Q&A - Digital Communication, Modulation & Modems

Answer /discuss the following 15 questions. Your answers should have detailed explanations. Topics: Digital communication, Pulse code modulation, line code, Frequency shift keying, phase shift keying, Quadrature amplitude modulation, constellation. 

Questions:

1) Define these acronyms PAM, PWM, PPM, PCM, TDM, FDM.

2) Is pulse modulation a real modulation? 

3) What are the advantages/disadvantages of PPM (Pulse Position/Phase Modulation), over PAM, PWM? 

4) In which digital modulation technique are the class-D power amplifiers used? 

5) What did Harry Nyquist in 1928 first demonstrate mathematically? 

6) Is this a correct statement? "Analog signals are quantized to the closest binary value provided in the digitizing system". 

7) What is "Aliasing" or "Foldover distortion"? 

8) What is the minimum periodic sampling rate required for perfect reconstruction, if the band-limited signal has 12 KHz bandwidth? 

9 What is it called If information is modulated on width of a pulse?

10) How do you reconstruct a baseband signal from its samples? 

11) What is an undesired byproduct of mixing called? 

12) What are the 3 steps of PCM (Pulse Code Modulation) coding?

13) Explain what digital sampling is.

14) What is the typical value of the S/H (Sample / Hold) circuit capacitor? 

15) What is the number of quantization levels of a 16-bit A/D?