Yashwantrao Chavan Maharashtra Open University 2006 Certification TES Communication Engineering - I - exam paper

TES071/EE/20070812
Communication Engineering - I
Time : 180 minutes Marks : 100
Instructions for the students :
1. All ques. are compulsory.
2. “Long ans kind ques. (LAQ)” is a supply kind ques. of 20 marks,
which require typical ans of about 60-80 lines in about 32-40 minutes.
3. “Short ans kind ques. (SAQ)” is a supply kind ques. of five marks,
which require typical ans of about 15-20 lines in about 08-10 minutes.
4. Use of non-programmable kind of scientific calculator is allowed.
5. Draw neat diagrams wherever necessary.
6. presume suitable data if necessary.

Long ans kind ques. (LAQ’s)
1. (a) Prove that if a white Gaussian noise of spectral density

0 N is filtered by RC low pass filter, then avg. noise
power at the output of filter is provided as

n0 0 c P = pN f where c f is cutoff frequency of the filter.
(b) Classify the noise sources and discuss them in brief.


2. (a) Derive mathematical expression for AM wave.
(b) What is angle modulation ? define Armstrong method of
generating FM waves.


3. (a) Draw a block diagram and compare High level AM
transmitter with low level AM transmitter. Why is it not
needed in AM ?
(b) define Pre-emphasis circuit with a suitable diagram.


4. (a) define AM superheterodyne radio receiver with a block
diagram.
(b) discuss with a block diagram dual channel SSB receiver.


Short ans kind ques. (SAQ’s)
5. What is RF oscillator ? discuss 1 in Brief. 5
6. explain the advantages and disadvantages of AM with reference
to FM.

7. A transmitter radiates 1200 watts of power under carrier
conditions. If this carrier is modulated simultaneously by two
tones of 20% and 40%, determine the total power radiated.

8. define TRF radio receiver with a suitable block diagram.

Earning:   Approval pending.