Question

The first stage in the detection of amplitude modulated signal is:
(A) Amplifier
(B) IF stage
(C) Detector
(D) Rectifier

Answer 1

Hint: To answer this question we should be having a basic knowledge about the amplification process of the modulated signal. In the process of the modulation the amplifier is placed right at the very base of the antenna. To answer this question, we need to give a detailed explanation for the amplification of a modulated signal.

Complete step by step answer:
Amplitude Modulation or AM is defined as a form of modulation in which the amplitude or the intensity of the waveform is varied in line with the waveform of the respective modulating signal.
So as a part of the modulation process, sidebands are created that extend out either side of the carrier. This is carried out by the amplification of the wave using the amplifier.
We should also know that the audio waveform modifies the amplitude of the carrier wave and thus determines the envelope of the waveform.
In the frequency domain, amplitude modulation produces a signal with the power concentrated at the carrier frequency and two adjacent sidebands.
Each of the sideband is equal in bandwidth to that of the modulating signal, and is a mirror image of the other.
Therefore, we can say that the first stage in the detection of amplitude modulated signals is amplifier.

Hence the correct answer is option A.

Note: We should be having a clear idea about the detection of amplitude modulated waves. So the very first step of detection is the process of recovering the modulating signal from that respective carrier wave. Then the process is followed by transmitted messages getting attenuated in the propagation by the channel.