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Electronics and Communication Engineering - Communication Systems

Exercise : Communication Systems - Section 5
46.
In a perfect conductor the resistor noise is
maximum
zero
very high
almost infinite
Answer: Option
Explanation:

A perfect conductor does not generate noise.

47.
An RF carrier of 12 kV at 1 MHz is amplitude modulated by 1 kHz signal having peak value of 6 kV. The modulation pattern is seen on CRO screen. The voltage indicated will be
18 kV
1.001 kV
6 kV
36 kV
Answer: Option
Explanation:

Modulation pattern on CRO will show peak to peak value = 2 (12 + 6) = 36 kV.

48.
In push pull amplifier, each transistor conducts for
180°
360°
90°
45°
Answer: Option
Explanation:

In push pull circuit each transistor conducts for 180° so that complete conduction for 360° occurs. Hence minimum distortion and maximum efficiency.

49.
In the television system in India, each channel is allowed a bandwidth of
20 MHz
12 MHz
7 MHz
3 MHz
Answer: Option
Explanation:

Each channel is allowed a bandwidth of 7 MHz.

50.
A diode detector load consists of 0.01 μF capacitor in parallel with a 5 k ohms resistor. The maximum depth of modulation without diagonal clipping at modulating frequency of 1000 Hz and 10 kHz is
0.76, 0.24
0.95, 0.3
0.24, 076
0.3, 0.95
Answer: Option
Explanation:

.

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