University of Mumbai 2008-4th Sem B.E Electrical and Electronics Engineering Comnication Engineering-I - Question Paper

Communication Engineering-I Sem IV June 2008

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Con. 2653-08.    (REVISED COURSE)    CO-9724

(3 Hours)    [Total Marks : 100

N.B.; (1) Question No. 1 Is compulsory.    M

(2)    Attempt any five questions including the compulsory question

(3)    Assume suitable data stating the same clearly

1 (a) State and prove frequency shifting property of Fourier transform Give its application    4

(b) List the advantages ol wideband frequency modulation.    4

<c) Describe briefly how frequency modulation can be used for generation of phase    6 modulation. List the parameter to be taken care off during operation/conversion,

(d) Describe in brief the operation of yagi d_a Antenna using suitable dlagramatic    6 representation and find the power that can be transmitted when used (or transmission.

2.    (a) For the three stage, double tuned RF amplifier with an RF equal to 1000 KHz 10

and coefficient of coupling k = 0 01,

Determine

(i) Bandwidth for each individual stage

(u) Bandwidth for the three stages cascaded together.

(b| Draw the block diagram ol a high level AMDSBFC transmitter. Represent waveform 10 at each stage. Explain in brief the function of each block in the receiver

3.    (a) Sketch the circuit and explain the working of Foster Seeley discriminator for FM 10

detection. Give phasor diagram and discriminator response curve

(b) For an angle modulated carrier :    10

V_c = 4 cos (2n 300 MHz t)    

With -75 KHz of frequency deviation due to modulating signal and a single frequency interfering signal V_n = 0-2 cos (2tt 300-015 MHz t)

Determine

(i)    Frequency of the demodulated interference signal.

(ii)    Peak and rms phase and frequency deviation due to interfering signal.

(iii)    S/N ratio at the output of the FM demodulator.

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5.    (a) The channel in the communication receiver is shared on time basis. Total bandwidth 10

of channel is 10 MHz. Find how many signals can be transmitted on the time sharing basis and bandwidth of each signal to be shared. Draw the block diagram arrangement for implementing the communication between transmitter and receiver Draw waveform for transmitted and received signal.

(b)    Explain intermodulation distortion in communication system using suitable waveform 5 representation

(c)    Define composite baseband signal draw and explain the composite baseband signal 5 transmission system for bandwidth of 48 KHz.

6.    (a) What is the meaning of Polarization of Antenna. Compare the performance ol 10

grounded and ungrounded antenna.

What are the advantages of using different type of polarization.

(b> Find the convolution of following function    10

U W =

i₂ (t) = u(t-2)

Use graphical convolution method.

7 (a) What is the traking error in a radio receiver. Explain three point traking.    5

(b) What is capture effect ? Use suitable waveform to represent it.    5

<c) Sketch the block diagram of Delta Modulation Transmitter Explain the following 10 with appropriate waveforms:

(i) Slope overload error (Ii) Hunting error Also state remedies for these error.

Attachment: university-of-mumbai-2008-b-e-electrical-and-electronics-engineering-51168-1.pdf

Earning:   Approval pending.