Osmania University (OU) 2006-2nd Sem B.E Electronics & Tele-Communication Engineering 3/4 (E.C.E)(ESTER)SUPPLEMENTARY ,emr, Digital communication systems - Question Paper
B.E 3/4 (E.C.E)(II-SEMESTER)SUPPLEMENTARY EXAMINATION,December,2006
Digital communication systems
VI W"' M
B.6. 3/4 (ECE) Ii Semester (Supplementary) Examination, December 2006 Subject: Digital Communication Systems
Time : 3 Hours} {Max. Marks : 75
Note : Answer AH questions of Part - A and Answer any five questions from Part-B, Assume any data if missing .
PART-A (25 Marks)
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1. |
Discuss about maximum length shift register codes. |
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2. |
Explain the terms processing gain and jamming. |
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3. |
Define PN sequence and give an example. |
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4. |
Define information and entropy of a discrete memory less source. |
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5. |
List the advantages of convolution codes over block codes. |
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6. |
Distinguish between base band transmission and band pass | |
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transmission. |
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Calculate the capacity of a low pass channel with a usable band | ||
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width of 3 KHZ and S/N = 100 at the channel output. |
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8. |
What is companding ? Draw the input - output characteristics of | |
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compressor. |
(3) | |
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9. |
List the advantages and disadvantages of Delta modulation over | |
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PCM. |
(3) | |
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? |
(2) |
library
PART B (50 Marks) vi V S R Engg, Collars
t>erV<u HYDERABAD
11 .(a) v JMeStgthe expression for optimum gain in DPCM.
(b) Derive the condition for optimum quantization step In case of (I) Uniform quantization
(ii) Non- uniform quantization
12.(a) Derive the channel capacity of a binary symmetric channel with a symbol transmission error probability P*.
(b) Find the channel capacity for the channel shown below.
13.(a) Define channel coding theorem and explain the need of channel coding,
(b) Consider the (15,11) Cyclic Hamming code generated by g(x) = 1+ x + x4
| (i) Determine the parity polynomial h(x) of this code
(ii) Determine the generator polynomial of its dual code (Hi) Find the generator and parity matrices in symmetric form
14.(a) Consider the (3,1,2) convolution code with g(1) * (110), g(2) * (101), g<3>*(111),
(I) Draw the encoder block diagram (iS) Find the generator matrix *G
(b) Compare binary and quaternary modulation schemes.
15.(a) Describe the structure of feed back shift register for generating PN sequences.
(b) Discuss about synchronization and tracking of frequency HOP spread spectrum signals.
16.(a) Compare correlation receiver with matched fitter receiver,
(b) Derive an expression for bit error rate for coherent binary FSK.
17. Write short notes on the following : LIBRARY
MVSR Engg. College,
(a) p - law and A-Law HYDERABAD
(b) BCH codes
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Attachment: |
| Earning: Approval pending. |
