Question

The types of modulation employed in India for radio transmission is.
A. Pulse modulation.
B. Frequency modulation
C. Amplitude modulation.
D. Phase modulation

Answer 1

Hint: Amplitude modulation (AM) is a modulation technique that is used in electronic communication, for transmitting information through the radio carrier wave
In amplitude modulation, the amplitude of the carrier wave is modified in proportion to the waveform being transmitted.
The loudspeaker or the television pixels' light intensity are produced waveforms.

Complete step by step solution:
Free propagation of signals possesses considerable power. a characteristic of a high-frequency signal called carrier signal which is modified with respect to our original signal.
The amplitude of the carrier is modulated in amplitude modulation. The carrier is always a periodic signal. Based on the Fourier transform, all periodic signals are denoted as a sum of sines or cosines.
Thus a carrier signal can be written as follows,
$$f\left(t\right)=a_0+a_{1}cos\left(wt\right)+a_{2}cos\left(2wt\right)+...$$
 Let your original signal be $$m\left(t\right).$$
Now a signal can be represented in two domains. They are the time domain and frequency domain. A time-domain signal is equal to the Fourier transform of that signal in the frequency domain
For radio broadcasting, the amplitude modulation technique is used.

Note:
Modulation is the most important process of the communication system.
Modulation is defined as the process of some characters like line amplitude, frequency, phase of a high-frequency signal wave is varied following instantaneous value intensity of the low-frequency signal wave
The need for modulation is To separate signals from different transmitters.