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Electronics and Communication Engineering - Communication Systems

Exercise : Communication Systems - Section 6
21.
Consider the draw backs
  1. Slope overload
  2. Serration noise
  3. Granular noise
Which of these draw backs does Delta modulation have?
1 and 2 only
2 and 3 only
1 and 3 only
1, 2, 3
Answer: Option
Explanation:

In delta modulation the, recovered waveform may be dc whereas the original signal is not dc. This noise is called granular noise.

22.
It is required to increase the maximum range of a radar by a factor of two. The peak power transmitted in the radar system has to be increased by a factor of
2
4
8
16
Answer: Option
Explanation:

Range μ (Power)0.25

23.
Armstrong F.M. transmitter performs frequency multiplication in stages
to increase the overall S/N
for convenience
to reduce the bandwidth
to find the desired value of carrier frequency with frequency deviation
Answer: Option
Explanation:

where (Δf) is the frequency deviation.

24.
A source generates three symbols with probabilities 0.25, 0.25, 0.50 at a rate of 3000 symbols per second. Assuming independent generation of symbols, the most efficient source encoder would have average bit rate is as
6000 bits/sec
4500 bits/sec
3000 bits/sec
1500 bits/sec
Answer: Option
Explanation:

Use Shannon Fano coding.

(0.25) is encoded as 01

Number of bits/sec

= 0.25 x 3000 x 2 + 0.25 x 3000 x 2 + 0.5 x 3000

45000 bits/sec.

25.
The filter circuit for feeding tweeter has
an inductance in series and a capacitance in parallel
a capacitance in series and an inductance in parallel
a resistance in series and a capacitance in parallel
a capacitance in series and a resistance in parallel
Answer: Option
Explanation:

Series capacitance and shunt inductance is high pass circuit.

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