The expected answers were:
(i) Demodulation: It is a means by which the audio information
is extracted or removed from the carrier signal.
(ii) Automatic frequency control: It is a means by which a portion
of the output frequency of the IF stage of an FM receiver is detected and used to control the receivers oscillator frequency to ensure a constant IF frequency.
(iii) Automatic Gain Control: It is a means by which the amplitude
of the IF signal is deflected into a d.c. voltage to maintain a
constant output(volume).
Advantages of Frequency Modulation over Amplitude Modulation
- All types of noise and interferences are eliminated.
- The modulated signal contains all fundamental and harmonic frequency of the signal.
- Less power is needed in the modulation process.
The question was on Communication System. It was popular with the candidates. The performance of the candidates was not encouraging.
