M.Sc. (Semester (CBCS) Examination Oct/Nov-2017
Electronic Science
COMMUNICATION SYSTEM
Day Date: Tuesday, 21-11-2017 Max. Marks: 70
Time: 10.30 AM to 01.00 PM
Instructions: Q.1 and Q.2 are compulsory.
Attempt any three questions from Q. 3 to Q.7.
All questions carry equal marks.
Use of nonprogrammable calculator is allowed.
Q.1 Select the correct alternatives:- 08
When modulation index of an AM wave is increased from 0.5 to the
transmitted power
Remains the same Increases by 25%
Increases by 33.3% Increases by 50%
Quantizing error occurs in
TDM FDM
PCM PWD
A mobile telephone has a range of about
50 km 10 km
1 km 0.1 km
In single tone AM modulation, the transmission efficiency for m 1 is

33.3% 50%
100% 16.65
PAM stands for
Phase Angle Modulation Phase Amplitude Modulation
Pulse Amplitude Modulation Pulse Angle Modulation
A signal is sampled at 8 kHz and is quantized using 8 bit uniform
quantizer. Assuming SNRq for a sinusoidal signal, the correct statement
for PCM signal with a bit rate of R is
R 32 KbPs, SNRq 25.8 dB R 64 KbPs, SNRq 49.8 dB
R 64 KbPs, SNRq 58.8 dB R 32 KbPs, SNRq 49.8 dB
Generally a VCR has
Four stationary video heads Two stationary video heads
Four rotating video heads Two rotating video heads
An RF carrier of 12 kV at 1 MHz is amplitude modulated by 1 kHz signal
having peak value of 6 kV. The modulation pattern is seen on CRO
screen. The voltage indicated will be
18 kV 1.001 kV
6 kV 36 kV
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SLR-MH-319
Q.1 State true and false 06
A video monitor is exactly similar to TV receiver.
A modem can be used to translate data from digital to analog only.
De-multiplexing is the process of allowing two or more signals to share
the same medium or channel.
The range of electromagnetic signals encompassing all frequencies is
referred to as the electromagnetic spectrum.
Modulation makes the information signal more compatible with the
medium.
Simplex communication refers to a one-way transmission type system.
Q.2 Attempt the following:-
Explain the operation of Dual Slope detector. 05
Differentiate between Delta modulation and Pulse modulation. 05
Explain the terms:- Half duplex ii) Full Duplex 04
Q.3 Explain the operation of an A.M. receiver with a neat block diagram. 10
Explain PLL as FM detector. 04
Q.4 Differentiate between FSK and ASK and PSK. 08
Explain the basic principle of DPSK with a block diagram. 06
Q.5 What is frequency hopping? Explain in detail. 08
Explain the process of tracking of DS signal. 06
Q.6 Explain the working principle of frequency doubler and tripler. 08
Discuss the construction and working of VCO. 06
Q.7 Discuss Direct Sequence Spread Spectrum. 08
Explain the acquisition of DS signal. 06