02-11-2012, 06:28 PM
B.E/B.Tech EXAMINATIONS,NOVEMBER/DECEMBER 2009
COMPUTER SCIENCE AND ENGINEERING
CS36-ANALOG AND DIGITAL COMMUNICATIONS
Time:3hrs Maximum:100 marks
Answer all questions
PART A-(10X2=20 marks)
1.A carrier wave is represented by equation s(t)=12sinwt.Draw the wave form of an AM wave for depth of modulation of 0.5.
2.Compare FM with AM
3.What is coherent detection?
4.Why is binary ASK called on-off keying?
5.What are the errors in DM?
7. What are the two methods of error detection and correction?
8.What do you mean by signaling rate?
9.Define processing gain
10.What is CDMA?
PART A-(5X16=80 marks)
11.(a)(i)The output voltage of a transmitter is given by 500(1+0.4sin3140t)cos6.28X10^7t
This voltage is fed to a load of 600 ohms.Determine
3.Carrier power (9)
(ii)Explain i detail about superheterodyne receiver(7)
(b)(i)Carrier frequency modulated with a sinusoidal signal of 2kHz resulting in a
maximum frequency deviation of 5kHz.Find
2.Bandwidth of modulated signal (4)
(ii)Explain the method of generating FM signal using indirect method(12)
12.(a)(i)Explain the coherent binary FSK system with a neat diagram of transmitter and receiver(12)
(ii)Enumerate the advantages and disadvantages of FSK over PSK system(4)
(b)(i)Explain the generation and detection of coherent QPSK system in detail(12)
(ii)What is DPSK?Explain its bandwidth requirements.
13.(a)(i)Explain in detail about DPCM with suitable diagram(10)
(ii)1kHz signal is sampled by 8kHz sampling signal and the samples are encoded with 12
bit PCM system.Find
1.Required bandwdth for PCM system
2.Total number of bits in the digital output signal in 10 cycles(6)
(b)(i)Write short notes on ISI(6)
(ii)What is eye pattern?Explain how is the performance of a baseband pulse transmission
system measured with this?(10)
14(a)(i)Write short notes on error correcting codes
(ii)Find the generator polynomial of (7,4) cyclic code and find the codeword for the message
(b)Explain in detail about the serial interface with its control signals and timing information
15(a)(i)What are pseudo noise sequences?How are they generated?(6)
(ii)Explain dirct sequense spread spectrum system in setail(10)
(b)(i)Explain 2 types of FH spread spectrum systems with suitable diagrams(16)
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