| COMMUNICATION SYSTEM-II |
| PAPER NO. 1 |
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| PUT ON: Dec, 2K2 |
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EC-304 COMMUNICATION SYSTEM-II (B.Tech 6th & 7th Semester, 2122) Time : 3 Hours Maximum Marks : 60 NOTE:- This paper consist of Three Sections. Section A is compulsory. Do any Four questions from Section B and any two questions from Section C Section-A Marks : 20 1(a) Plot typical examples of analog and digital signals. Explain their difference. (b) State Sampling Theorm. (c) Differentiate between Coherent and non-coherent FSK detector. (d) Explain Quadrature Phase shift keying. (e) Mention applications of spread spectrum modulation. (f) Explain autocorrelation of a PN sequence. (g) Enlist the various services of GSM. (h) What is the need of power control in cellular systems? (i) Enlist the various elements of switching. (j) Why do we use layered protocols in computer communication? Section-B Marks:5 Each 2. (a) Explain the operation of a data modulation system. How will you overcome limitations of this system? (b) Discuss the need for companding. 3. (a) With the help of block diagrams, explain direct sequence spread coherent binary phase shifting keying in brief. (b) What is clustering in a PN sequence? 4. (a) Describe the main methods of radio transmission in mobile communcation systems. (b) Give the operational features of a paging system. 5. (a) Give the block diagram of an OSI model (b) Mention the features of E-mail services. 6. A communication system is designed to have a BER of 10-5 or less. Find the minimum Eb/No decibels required to achieve an error rate of 10-5 for BPSK signaling. Section-C Marks : 10 Each 7. The information in an analog voltage waveform is to be transmitted over a PCM system with a +-0.1% accuracy (full scale). The analog waveform has an absolute bandwidth of 100 Hz and an amplitude range of -10 to +10 V. Determine (a) The minimum sampling rate needed. (b) Number of bits needed in each PCM word. (c) Minimum bit rate required in the PCM signal. 8. Explain the concept of frequency reuse channels. What is frequency reuse distance? Show that channel to interference ratios from the first tier of six interference with that from twelve interferers (first and second tiers) are given by 18.72 dB and 18.46 dB respectively. 9. Make a comparative study of BPSK, QPSK and DPSK-digital modulation technique Give the probability of error for QPSK when each signal s1, s2, s3 and s4 are equally likely to be transmitted. |
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