Exercise: Communication Systems

Questions for: Communication Systems

In a two stage cascade amplifier, each stage has a gain of 10 dB and noise figure of 10 dB. The overall noise factor is
A:
10
B:
1.09
C:
1
D:
10.9
Answer: D

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Consider the following statements about Yagi Uda antenna
  1. It is unidirectional
  2. Its gain is about 7 dB
  3. It is used at VLF
  4. The optimum separation is 0.11
Which of the above are correct?
A:
1 and 2 only
B:
1, 2, 4 only
C:
1, 2, 3, 4
D:
1 and 4 only
Answer: B

This antenna is for UHF and VHF bands.

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The maximum range of a transmitter depends on
A:
its frequency
B:
its power
C:
both its frequency and power
D:
none of the above
Answer: C

Both power and frequency determine the maximum range.

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Modulation is also called detection.
A:
True
B:
False
C:
D:
Answer: B

Demodulation is called detection.

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In an FM system, when the AF is 500 Hz and the AF voltage is 2.4 V, the deviation is 4.8 kHz. If the AF voltage is now increased to 7.2 V, the new deviation will be
A:
4.8 kHz
B:
9.6 kHz
C:
14.4 kHz
D:
28.8 kHz
Answer: C

Δf' = 2 x 7.2 14.4 kHz

New frequency donation will be 14.4 kHz.

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