Question

Assertion: A FM signal is less susceptible to noise than an AM signal.
Reason: In FM transmission, the message signal is in the form of frequency variations of carrier waves. During the modulation process, the noise gets amplitude modulated.
A) Both ASSERTION and REASON are true and REASON is the correct explanation for ASSERTION.
B) Both ASSERTION and REASON are true but REASON is not the correct explanation for ASSERTION.
C) ASSERTION is correct but REASON is incorrect
D) Both ASSERTION and REASON are incorrect.

Answer 1

In case of a Frequency Modulation, the signal is carried by the modulation of frequency of the carrier signal but in case of an Amplitude Modulation the signal is carried by the modulation of the amplitude of the carrier wave. We can easily approach the answer if we know how noise affects these processes.

Complete step by step answer:
We know that Frequency Modulation (FM) is used for signal transmission by modulating the frequency of the carrier wave. In other words, the instantaneous voltage of the carrier wave is varied by the instantaneous voltage of the signal wave so that it will carry or transmit the signal from the sender to the receiver by keeping the amplitude constant.

In Amplitude Modulation (AM), the signal wave is transmitted by the carrier wave by changing the amplitude of the carrier waves or we can say that the instantaneous voltage of the carrier wave is varied by the instantaneous voltage of the signal wave so that it will carry or transmit the signal from the sender to the receiver by keeping the frequency constant.

Noise which can be produced due to man-made activities or due to the atmospheric interference, can have its impact only on amplitude. As in case of Frequency Modulation (FM) the amplitude remains constant, there is no noise produced. But in Amplitude Modulation (AM), the amplitude is not constant, hence the receiver gets noise along with the transmitted signal.

So the answer will be option (A).

Additional information: Frequency Modulation (FM) is preferred over Amplitude Modulation (AM) for radio because of its less noise reception.

Note: We should always remember that the frequency and phase remains constant in case of Amplitude Modulation (AM) and for the Frequency Modulation (FM), the amplitude and phase remains constant. Amplitude modulation is mostly used in many areas of electronic communication, most commonly for transmitting messages with a radio carrier wave. Frequency modulation is widely used for FM radio broadcasting and also used in telemetry, radar, two-way radio systems, sound synthesis, and video transmitting systems.