CE model1.doc
- 1. EC8395- COMMUNICATION ENGINEERING PART A 1. What is the need for modulation? 2. What is the relationship between frequency and phase modulation? 3. In a PCM system the number of bits per symbol is raised from 8 to 10. Then calculate the SNR improvement in dB. 4. Define the term slope overload noise. 5. How does pulse shaping reduce inter symbol interference? 6. Write the difference between DPSK and BPSK. 7. List out the properties of cyclic code. 8. State source coding theorem. 9. What is meant by slow frequency hopping and fast frequency hopping? 10. Mention any two features of spread spectrum modulation. 11. What are the advantages of SSB-SC modulation? 12. What are the main problems in TRF receivers? How are these problems overcome by superheterodyne receiver? 13. What is aliasing? 14. What is the principle of delta modulation? 15. What are the advantages of QPSK as compared to BPSK? PART B 16. With the help of neat block diagram explain about the generation of SSBSC wave and demodulation. 17. (i) Draw the block diagram of superheterodyne radio receiver and explain its operation. What are the advantages of this receiver? (ii) Differentiate between narrowband FM and wideband FM. 18. (i) Discuss about the generation of PAM and its demodulation. (ii) Explain the working of differential PCM with relevant diagrams. 19. (i) Explain delta modulation in detail with the help of transmitter and receiver and also Explain the limitations of DM. (ii) Explain about frequency division multiplexing. 20. Explain BPSK system with the help of transmitter and receiver and state its advantages and disadvantages over other system. 21. Explain QAM system with its transmitter, receiver and signal space representation. 22. A discrete source emits symbols with the following probabilities p(x)=(0.4, 0.19, 0.16, 0.15 and 0.15) using Shannon-Fano code and Huffman code determine the coding
- 2. Efficiency and redundancy. 23. (i) Write short note on linear block codes. (ii) Explain the viterbi algorithm for convolutional codes. 24. (i) Explain the method to generate a pseudo-noise sequence. (ii) What is CDMA? Compare its features with TDMA. 25. With a neat transmitter and receiver block diagram of direct sequence spread coherent Phase shift keying, explain its principle of operation. 26. With the help of a transmitter and receiver block diagram, explain the principle of operation (FH) frequency hopped spread spectrum system