Exercise: Communication Systems

Questions for: Communication Systems

A narrow band noise n(t) has symmetrical spectrum and has power density spectrum 0.2 x 10-6. The power density of quadrature component is
A:
0.2 x 10-6
B:
10-7
C:
4 x 10-7
D:
5 x 10-8
Answer: B

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The typical squelch circuit
A:
cuts off IF amplifier when AGC is minimum
B:
cuts off IF amplifier when AGC is maximum
C:
cuts off audio amplifier when carrier is absent
D:
eliminates RF interference when signal is weak
Answer: C

To suppress noise when carrier is absent, squelch circuit cuts off audio amplifier.

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A TV receiver has a width of 60 cm. The aspect ratio is 4/3. The required EHT supply is about
A:
29 kV
B:
2.9 kV
C:
45 kV
D:
4.5 kV
Answer: A

EHT supply is 1 kV per diagonal inch.

Height = 60 x = 45 cm.

Diagonal = .

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Vidicon and plumbicon operate on the principle of
A:
photo conduction
B:
photo emission
C:
photo voltaic
D:
none of the above
Answer: A

Photo conduction uses the fact that resistivity of some materials depends on intensity of light falling on their surface.

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Consider the following
  1. A signal f(t) and its Hilbert transform fh(t) have the same energy density spectrum
  2. A signal f(t) and its Hilbert transform, fh(t) have the same auto correlation function
  3. A signal f(t) and its Hilbert transform are mutually orthogonal
Which of the above are true?
A:
1, 2 and 3
B:
1 and 2 only
C:
1 only
D:
2 and 3 only
Answer: A

All are correct.

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