Master of Science I (Electronic Science) Examination: Oct/Nov
2016 Semester I (Old CBCS)
SLR No. Day
Date Time Subject Name Paper
No. Seat No.
SLR SJ
339
Monday
21/11/2016
10:30 AM
to
01.00 PM
Communication Systems
C
III
Instructions: All questions carry equal marks.
Q.1 and Q.2 are compulsory.
Attempt any THREE questions from Q.3 to Q.7
Total Marks: 70
Q.1 Choose correct alternative 08
Amplitude modulation causes the amount of transmitter power to
Increase Decrease
Remain the same Double
In FM, the change in carrier frequency is proportional to what attribute of
the modulating signal.
Angle Frequency
Amplitude Tone
The process of impressing intelligence on the carrier is
Modulation Detection
Mixing Demodulation
Two binary values are represented by two different frequencies in
ASK FSK
PSK DPSK
The main advantage of TDM over FDM is that, it
needs less power needs less bandwidth
needs simple circuitry gives better S/N ratio
In CDMA, the bit rate of the digital data is called
Chipping frequency Information rate
Chip Epoch
What is the category of data transmission, if the binary pulse is
maintained for the entire bit time?
Return to zero Bipolar
Non-return to zero Unipolar
DSSS technique expands the bandwidth of a signal by replacing each data
bit with
n 1 bits n bits
n bits both a b
Page 1 of 2
State whether following statements are true or false: 06
TDM system is more immune to inter channel cross-talk as compared to
FDM systems.
The process of impressing information on the carrier is called mixing.
Mixer stage mainly determines a communication receiver's sensitivity.
BPSK stands for binary pulse shifting key.
In half duplex communication system, information is transmitted in both
directions but the flow is only one way at a given time.
Frequency hopping is the easiest spread spectrum modulation to use.
Q.2 Attempt any three: 14
Explain the necessity of modulation in electronic communication system.
State and explain Sampling theorem.
Write a note on data formats.
Discuss the basic concepts of spread spectrum modulation.
Q.3 Describe the operation of an AM receiver and detector circuits. 10
What is a PLL? Explain. 04
Q.4 Draw the block diagram of low and high level modulated AM transmitters
and explain their functioning.
10
Write a note on audio amplifier. 04
Q.5 With neat diagram, explain in detail, the pulse amplitude modulation and
demodulation circuits.
10
Write a note on generation of PTM. 04
Q.6 Discuss FSK modulation and demodulation techniques in detail. 10
Write a note on asynchronous transmission. 04
Q.7 With neat block diagram, explain the working of a direct sequence spread
spectrum (DSSS) transmitter and receiver.
10
Write a note on applications of spread spectrum. 04