What is the modulation? Why is it necessary?

Hint: In this question, we are going to discuss the definitions of Baseband Signal and Carrier Signal, What is modulation, and what are the different types of modulation and why modulation is necessary for transmitting the messages.

Complete step-by-step answer:
For any communication, messages need to be transmitted from the sender to the receiver. But the frequency of the original message(baseband signal) is very low and it cannot be transmitted over long distances. The Carrier signal is a high-frequency periodic signal which carries the baseband signal and helps the baseband signal get transmitted over long distances. Modulation is the process of changing the properties of the carrier signal (like the amplitude of the carrier signal) according to the baseband signal. Based on what properties of the carrier signal are changed, Modulation is of three types

1.) Amplitude Modulation
2.) Frequency Modulation
3.) Phase Modulation

Now let’s discuss why modulation is necessary. The first thing we need to discuss is:
Size of the Antenna:

The relationship between the length of the antenna and wavelength is

$L = \dfrac{\lambda}{4}$

The relationship between wavelength and frequency is

$\lambda = \dfrac{c}{frequency }$

So length of the antenna is inversely proportional to the frequency. Thereby modulation increases the frequency and reduces the antenna length.

To avoid Interference:

If we didn’t modulate the signal then the various signals traveling through the same channel interfere with each other. As a result, important data is lost. To prevent this from happening we do modulation. By modulating we ensure that the different types of signals do not interfere with each other.

Note: Types of modulation can also be explained based on analog and digital modulation. Analog modulation is done for analog message signals whereas digital modulation is done for digital message signals. By modulating a signal we also ensure that the effective power emitted by the antenna is high.