Exercise: Communication Systems

Questions for: Communication Systems

In a TV, studio the function of vision switcher is to
A:
edit television programs
B:
relay television programs
C:
control zoom lens
D:
mix audio and video signals
Answer: A

Viscon switcher has a provision to select any one or more of a large number of inputs and switching then on to outgoing circuits.

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Audio amplifiers need
A:
Bass control
B:
Treble control
C:
Both Bass and Treble control
D:
Either Bass or Treble control
Answer: C

Bass means low frequency tones and treble means high frequency tones.

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The open loop gain of an amplifier is 50 but is likely to change by 20%. If negative feedback with β = 0.1 is used, the change in gain will be about
A:
20%
B:
10%
C:
4%
D:
0.05%
Answer: C

.

Change in gain is about 4%.

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In the absence of noise, if C is channel capacity in bits/s, δf is channel bandwidth in Hz and N is number of coding levels. Then
A:
C = log2 N
B:
C = (δf) log2 N
C:
C = 2 (δf) log2 N
D:
C = 0.5 (δf) log2 N
Answer: C

Hartley law C = 2 δf log2N.

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Consider the following features of monochrome TV
  1. Number of lines per picture 625
  2. Interlace ratio 2 : 1
  3. Aspect ratio 4 : 3
  4. Channel bandwidth 8 MHz
As regards CCIR system B, which of the above are correct?
A:
1, 2, 3, 4
B:
1, 2, 3
C:
1, 2, 4
D:
2, 3, 4
Answer: B

Channel bandwidth is not 8 MHz.

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