Question

The picture signal in TV-broadcast is modulated in
\[A.\] SSB
$B.$ VSB
$C.$ FM
$D.$ DSB

Answer 1

Hint: We know that TV-broadcasting is an example of a communication system. Communication systems involve transmission, receiving, and processing information by electrical means. We also know that the process of superposition of audio frequency with radiofrequency waves is called modulation.

Complete step-by-step solution
We know that the process of superposition of audio frequency with radiofrequency waves is called modulation. During the process of modulation, the audio frequency waves which are to be transmitted are called modulating waves and the radio frequency waves which are superimposed on it are called carrier waves. The resultant superimposed wave is called a modulated wave.
TV-broadcasting is modulated by using VSB whose full form is Vestigial Sideband Modulation. During this type of modulation, a part of the signal which is known as vestige is modulated. SSB is not used in this process. The interference of waves is avoided by using a guard band of small bandwidth on either side of VSB.
Hence, option $(B)$ is correct.
Some advantages of VSB modulation are as follows:-
$(i)$ Highly efficient modulation.
$(ii)$ Reduced bandwidth.
$(iii)$ Easy transmission of low-frequency components.
$(iv)$Very good phase properties.
Disadvantages of VSB are as follows:-
$(i)$ Demodulation is not simple but very complex.
$(ii)$ Bandwidth is greater when compared to SSB.
The most important use of VSB is in the transmission of TV signals.

Note: We should always remember that VSB is used in the process and not SSB because removal of one sideband is not possible. Reduced bandwidth is required because the same information is present in both the signals and they are amplitude modulated. SSB stands for single-sideband modulation.