Anna University Chennai 2005 B.E Electronics and Microprocessors DIGITAL COMMUNICATION - Question Paper

PART-A
1.State bandpass sampling theorem.
2.What is the SNR of PCM system if number quantization fault is 2^8
3.What is an ideal Nyquist channel
4.What is mean by intersymbol interference.
5.Compare the probability of fault of PSK with that of FSK.
6.State the difference ranging from coherent and noncoherent binary modulation technique.
7.What is convolutional code
8.What is meant by BCH code.
9.What are the application of spread spectrum modulation
10.Define frequency hopping.

PART-B
11(a)(i)With supporting derivation prove that if a signal contains no frequencies higher than W Hertz,
it may be reconstructed from its samples at a sequence of points spaced 1/2W seconds apart.
(ii)Explain the principle of Deltamodulation and derive an expression for avg. output noise power
in deltamodulation.
(b)Derive the expression for SNR in PCM system and compare it with deltamodulation.
discuss how can the SNR be improved in a PCM system.
12(a)(i)With neat sketches , discuss the duobinary signalling scheme.
(ii)Write briefly about eye trend and adaptive equalisation for data transmission
13(a)(i)Draw the block diagram of QPSK transmitter and QPSK coherent receiver and discuss their
operation.
(ii)Discuss briefly about minimum shift keying for a CPFSK signal.
(b)(i)With necessary equations and signal space diagram , discuss briefly about FSK system.
(ii)Obtain probability of fault in terms of Eb/No for QPSK.
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Earning:   Approval pending.