M. Sc.(Electronic Science) (Semester I)(Old CBCS) Examination, 2017
COMMUNICATION SYSTEMS wateriI
Day Date: Saturday, 22-04-2017 Max. Marks: 70
Time: 10.30 AM to 01.00 PM
N.B. Questions NO.1 and 2 are Compulsory.
Answer any three questions from Q.NO.3 to Q.NO.7
All questions carry equal marks.
Use of non programmable calculator is allowed.
Q.1 Select the most correct alternative. 08
Demodulation is done in
Receiving antenna Transmitter
Radio receiver Transmitting antenna
CDMA technology in inherently resistant to
Interference Jamming
Both a b None of the above
In TV transmission, sound signal is modulated.
a)Amplitude Frequency
Phase None of the above
Which of the following noise does not occur in transistors?
Partition noise Shot noise
Flicker noise Resistance noise
The Intermediate frequency is 455 kHz. If the radio receiver is
tuned to 885 kHz, then local oscillator frequency is
455 kHz 1310 kHz
1500 kHz 1520 kHz
The standard value for intermediate frequency in AM
receivers is
a)455 KHz 580 KHz
10.7 MHz 50 MHz
For telegraphy, the most commonly used modulation system
is
PCM FSK
ASK Single tone modulation
DSSS technique expands band width of a signal by replacing
each data bit with
n+1 bits n-1 bits
n bits both a and c
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State True/False: 06
As the modulation level is increased, the carrier power remains
the same.
The polarities in RZ format uses the complete pulse duration.
A buffer amplifier acts as a high gain ac amplifier.
In pulse code modulation system, a large bandwidth is
required.
In CDMA, the bit rate of the digital data is called chipping
frequency.
A high Q tuned circuit will permit an emplifier to have high
selectivity.
Q.2 Answer the following: 14
Explain the Phase shift keying with its waveforms. 05
Briefly explain the sampling theorem. 05
What are the advantages of single side band transmission? 04
Q.3 Draw and explain circuit diagram of dual slope detector. 08
Explain Cross talk in TDM. 06
Q.4 Describe with a suitable circuit diagram and waveforms of single
transistor low level (emitter) AM Modulator.
10
What is delta modulation? 04
Q.5 Sketch the block diagram of F.M. receiver and explain. 10
Differentiate between FDM and TDM. 04
Q.6 Explain how PWM and PPM signals are generated? 10
What is the frequency hopping spread spectrum technique? 04
Q.7 Discuss a Class B audio amplifier. 08
Draw the NRZ and RZ code for the digital data 10110001. 06