M.Sc. (Semester III) (CBCS) Examination Nov/Dec-2018
Physics (Applied Electronics)
COMMUNICATION SYSTEM
Time: 2½ Hours Max. Marks: 70
Instructions: All questions are compulsory.
All questions carry equal marks.
Q.1 Multiple choice questions. 14
AM causes the amount of transmitter power
increases decreases
double remain the same
Envelop detection is concerned with the process of
mixing rectification
modulation heterodyning
The circuit that has the function of demodulating the frequency modulated
signal is
detector AFC
discriminator envelop detector
In FM, the amplitude of the modulated frequency wave at all times remains
dependent varying
high constant
What is the highest of modulation for AM?
100 80
75 50
ASK is the result of combination of shift keying and
digital amplitude
analog none of these
The binary values are represented by two different frequencies in
ASK PSK
FSK DPSK
The process of adding intelligence on the carrier is called
adding mixing
detection modulation
The PAM signal can be detected by
low pass filter high pass filter
band pass filter band stop filter
10) The main advantage of TDM over FDM is that, it
needs less power gives better S/N ration
needs less BW needs simple circuit
11) CDMA technology is inherently resistant to
interference jamming
both and none of the above
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12) What is the category of data transmission, if the binary pulse is maintained for
the entire bit time
unipolar bipolar
non-return to zero return to zero
13) Converting analog signals to digital is done by sampling and
quantizing mixing
compounding pre-emphasis
14) In full duplex communication system, the flow of information takes place in
both directions.
alternatively simultaneously
bit by bit None of the above
Q.2 Attempt the following (any Four) 08
Define low level modulation.
What do you mean by VCO?
Define PPM.
What is meant by delta modulation?
Explain simplex communication system.
Write note on (Any Two) 06
Balanced modulator
PLL
Quantization of signal
Q.3 Answer the following (Any Two) 08
Give a brief explanation on TDM.
Explain the generation of PTM.
Describe a transponder.
Answer the following (Any One) 06
With a neat diagram, explain frequency shift keying.
Give a brief explanation on cross talk in TDM.
Q.4 Answer the following (Any Two) 10
State and explain, Sampling theorem.
Explain frequency doubler and tripler circuits.
Write a brief note on CDMA.
Answer the following (Any One) 04
Write the advantages of FM over AM.
Write a brief note on asynchronous transmission.
Q.5 Answer the following (Any Two) 14
Describe with the help of neat diagram, the working of FM receiver circuit.
With a neat diagram, explain DPSK modulation and demodulation.
Write a detailed note on multiple access techniques.