Engineering BE Electronics and Computer Science Sem 5 December 2019 2019 Digital Communication Question Paper - Mumbai University | munotes

Questions asked in this paper

1. Q1 Question number ONE is compulsory
2. Q2 Attempt any THREE questions from remaining questions
3. Q3 All questions carry equal marks
   • a) Show that the mean of the sum of random variables is the sum of the means of the
   • c) Explain Binary Symmetric Channel 5
   • d) Derive the condition for maximum entropy of a source. How does entropy vary with
4. Q2 a) Draw the signal constellation for 16-QASK and hence find its Euclidean distance Compare it with the Euclidean distance of 16-QPSK. 10
   • b) With reference to 8-PSK explain transmitter and receiver with neat block diagram along with mathematical expression for transmitted signal. Draw constellation diagram and find its
5. Q3 a) A discrete memory less source has an alphabet of five symbols with their probabilities a shown
6. Q1 Construct Huffman code for each symbol and determine the following parameters: Entropy, Average code word length, code efficiency and code redundancy
   • ii) Determine the above parameters for Shannon-Fano code. 10
   • b) Explain FHSS giving appropriate diagrams. If the direct sequence spread spectrum system has the following parameters: Data sequence bit duration, PN chip duration, Tc= 1.5us, The probability of error is less than then calculate the Processing gain and Jamming Margin. 10
7. Q4 a) Explain the necessity of line codes. State different types of line codes. Plot power spectral density of NRZ signal. 10
   • b) Explain Duo binary encoder-decoder with a neat sketch. What is significance of precoder
8. Q5 a) Draw block diagram of BPSK transmitter and receiver and explain. Sketch signal space diagram and PSD of BPSK. 10
   • b) A (7,4) cyclic code is generated using the polynomial Find the code word if the data word is i) 0011, i1) by long division method. Draw the encoder and generate the code word for the same data tracing the path through the encoder. 10
9. Q6 Write short notes on following 20 marks
   • a) AWGN Channel
   • c) Eye Pattern
   • d) Matched Filter

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