# EC2301 Digital Communication May June 2014 Past Exam Paper

## Anna University Chennai EC2301 Digital Communication May June 2014 Past Exam Papers Free Download

Anna University Chennai
Question Paper Code:
B.E./B.Tech Degree Examination, May June 2014
Fifth Semester
Electronics and Communication Engineering
EC2301 Digital Communication
(Regulation 2008)
(Common to PTEC 2301 - Digital Communication for B.E. (Part-Time) Fourth Semester Electronics and Communication Engineering - Regulation 2009)
Time: Three Hours
Maximum: 100 Marks
Question Paper Type: Past Exam Papers
Note: New Subject Code in R-2013 is EC6501

PART - A (10 x 2=20 marks)
1. Classify communication channel?
2. State the demerit of digital communication.
3. What is the need for non-uniform quantization?
4. List any four speech encoding procedure?
5. Define hamming distance and hamming weight?
6. What are the requirements of line code?
7. What is ISI?
8. What is a matched filter?
9. What are the advantages of QPSK over PSK?
10. Draw the signal space diagram for QAM signal for M=8.

PART-B (5 x 16=80)
11.(a) i) Draw the block diagram of a digital communication system. Explain each block.
ii) Discuss the advantages of digital communication over analog communication.
Or
b) i) Define basis set. How they are useful in representing a signal?
ii) With an example. Explain how the basis set is determined by gram schemidt procedure.

12. (a) i) Explain non-uniform quantization techniques.
ii) Explain temporal waveform encoding technique.
Or
b) i) Describe the linear predictive coding technique in speech encoding.
ii) Explain model based encoding technique.

13. (a) Explain the Viterbi algorithm assuming a suitable convolutional coder and received bit stream.
Or
b) i) Brief about any one decoding procedure of linear block codes.
ii) Find a generator polynomial for a (7,4) cyclic code and hence find the code word for [1 0 0 0].

14. (a) i) Derive the expression for bit error probability of a matched filter.
ii) Explain a method of bit synchronization.
Or
b) Describe any one method for ISI control.

15. (a) i) Describe the following modulation methods:
1) PSK. 2) QAM. ii) Compare the performance of various digital modulation schemes.
Or
b) Discuss about the coherent detection of QPSK and non-coherent detection of ASK.