Question

The process of regaining of information from carrier wave at the receiver is called :
a. Modulation
b. Transmission
c. Propagation
d. Demodulation

Answer 1

Hint: In telecommunication the process of encoding some information in a carrier wave by varying one or more properties of the carrier wave is known as the Modulation. Regaining the encoded information from the carrier wave is just the opposite work of modulation.

Complete answer:
When some information signal is needed to transmit from one place to another, the main problem arises is to properly separate it from the noises present in the ambience.

To resolve this issue the original signal is superimposed with a very high frequency wave known as the carrier wave in such a way that its frequency gets modified according to the amplitude of the original information. This method is known as frequency modulation (FM).

Typically, the frequency of the carrier wave is chosen such that the signal to noise ratio FM transmission becomes much lower. Also, it requires much less power to transmit the same signal after frequency modulation. The encoding process is known as modulation and the decoding process is known as demodulation.

In both cases the R-L-C tank oscillator circuit is used to do the encoding and decoding.
Hence, the correct answer is option (D).

Note: In real life, FM broadcasting systems are mostly used to transmit various sound waves from various radio stations as an entertaining media. It’s typical frequency range varies from 88 to 108 MHz. It is also used in radar, telemetry, short range two-way communication, seismic prospecting, monitoring newborns via EEG etc.