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Electronics and Communication Engineering - Communication Systems

Exercise : Communication Systems - Section 6
31.
Some possible disadvantages of high level modulation in TV transmitters are
  1. Video monitor has to supply high video voltages upto several hundred volts into highly capacitive loads drawing high current at video frequencies
  2. The grid modulated stage presents a varying load to its driver
  3. The linearity and high video driving power present design problems
Out of above which are true?
1 only
1 and 2 only
1, 2 and 3
2 and 3 only
Answer: Option
Explanation:

All these are true.

32.
Beam width of an antenna is expressed in
metres
degrees
ratio of two powers
ratio of two angles
Answer: Option
Explanation:

Beam width is the angular separation between the two half power points on the power density radiation pattern. It is expressed in degrees.

33.
In broadcast television, the number of lines per frame is chosen to be odd number to
reduce the required bandwidth
improve resolution
reduce peak power requirement
make interlacing easier
Answer: Option
Explanation:

Odd number of lines per frame makes interlacing easier.

34.
In a picture tube, the video signal is applied to
cathode
grid
any anode
either cathode or grid
Answer: Option
Explanation:

Video signal is applied to cathode.

35.
If frames are repeated at 60 Hz and each frame has 525 lines, the time for scanning one horizontal line (for progressive scanning and no interlacing) is about
320 μs
32 μs
3.2 μs
0.32 μs
Answer: Option
Explanation:

.

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