University of Mumbai 2007-4th Sem B.E Electrical and Electronics Engineering Comnication Engineering -I - Question Paper
(%> flwtun icuJ'i'-i Z/yT-Con/2347-07. (REVISED COURSE) J ND-9383
(3 Hours) [Total Marks : 100
N.B.: (1) Question No. 1 is compulsory.
(2) Attempt any four questions from the remaining six questions
(3) Figures to the right indicate full marks.
t. (a) Draw the block diagram of super heterodyne AM receiver and explain function of 12 each block.
(b) Explain with examples any two properties of Fourier transform. 8
2. (a) Sketch the block diagram of Delta modulation transmitter. Explain the following with 10
appropriate waveforms.
(i) Slope overload error
(ii) Hunting error.
(b) Explain the circuit of Foster Seely Discriminator with the help of a neat circuit diagram 10 and phasor diagram.
3. (a) An amplitude modulated waveform has the form 10
X.(t) = 10 (1 -f 0.5) Cos 20007tt + 0.5 Cos 4000*1) Cos 20.000Ttt 1 (i) Sketch the amplitude spectrum of Xc (t)
(ii) Find the average power content of each spectral component including the carrier.
(b) Sketch the block diagram of PCM system with compander and explain its working. 6
(c) What is quantization noise ? 4
4. (a) Draw the block diagrams of Low level modulation and High level modulation and 10
differentiate between the two.
(b) Classify noise in communication system used in radio-wave propagation and explain 6 in brief.
(c) With suitable waveform explain inter modulation distortion. 4
5. (a) Explain in brief grounded and ungrounded antenna. 8
(b) What are 'tracking' and 'alignment' in communication receivers ? 8
(c) Why is the over modulation In AM system undesirable ? 4
6. (a) State and explain the Sampling theorem. 6
(b) What is a double conversion communications receiver ? State its advantages. 6
(c) Explain any two single sideband amplitude modulated systems. 8
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| Earning: Approval pending. |
