Anna University Chennai 2005 B.E COMMUNICATION ENGINEERING - Question Paper
Sunday, 24 February 2013 12:30Web
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Q.3 a. Show that the signal (7)
represents an SSB-SC
(i) obtain the expression for the missing side band.
(ii) Write expression for the DSB-SC.
b. If v(t) above is multiplied by , and then sent through a low-pass filter to recover the modulation (7)
(i) Show that the modulation is completely recovered if the cutoff
frequency of the low -pass filter is .
(ii) If the multiplying signal were , obtain the recovered
signal?
Q.4 a. How do we generate an FM signal? describe modulation index for single tone modulated FM signal. Under what conditions FM signal becomes narrow band FM. (7)
b. An FM broadcast station uses maximum frequency deviation of 75 KHz. The maximum signal frequency is limited to 15 KHz. Estimate the bandwidth of the FM signal. What would be the estimated bandwidth if the maximum signal frequency is limited to four KHz. (7)
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b. A telephone signal has maximum frequency of four KHz. It is limited in voltage ranging from -1V and +1V, and has unit variance. It is transmitted by using PCM. The needed signal to quantisation noise ratio is 40 dB. What is the minimum bandwidth needed for transmission? (7)
Q.6 a. With the help of neat diagrams, discuss the principle of Delta Modulation (DM) system. elaborate its main disadvantages? How does Adaptive Delta Modulation (ADM) overcomes the issues of DM system? (7)
b. What is meant by sampling? discuss the reasons to prefer flat-top sampled signals as compared to the natural - sampled ones. (7)
PART I
ans any 3 ques.. every ques. carries 14 marks.
Q.7 a. Explain the operation of a Pulse Radar with the help of block diagrams. elaborate the salient parameters of a Radar and how do every of these affect the Radar performance, discuss in brief. (7)
b. Derive Radar Range formula. What parameters affect the maximum radar range? (7)
Q.8 a. The auto correlation of a real-valued wide sense stationary process is described by
(6)
Show that
(i.e. is an even function)
b. Explain the terms : Entropy, mutual info capacity, channel capacity. elaborate their significances in communication? (8)
Q.9 a. What is the channel capacity of a white, band limited gaussian channel. Derive expression giving channel capacity of a noisy channel when bandwidth tends to be very large. (7)
b. How does coding help for fault detection and fault correction in the received signal? discuss the use of Block codes and discuss how coding/ decoding is done? (7)
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b. Name a few TV cameras and describe, in detail the operation & limitations
of 1 such camera. (7)
Q.11 Write short notes on any 2 of the following:
(i) A sonar system.
(ii) Radio direction finder.
(iii) Sampling theorem. provide its proof.
(iv) Generation of single side band and its detection. (7+7)
| Earning: Approval pending. |
