Question

Why is there a need for modulation?

Answer 1

Hint: Modulation is the branch of science which deals with communication. In communication, work processes on signals like modulation, frequency, transmission etc. There are three types of modulation: frequency modulation, amplitude modulation, phase modulation.

Complete step by step answer:
We know what communication is. It is nothing but exchanging the messages or information. This is what we do while communicating. We do communication through spoken words. This is communication.
Have you ever heard the radio? Our grandfather used to hear it for entertainment. Have you ever wondered how the sounds come from radio station to radio and then to our ears. Basically, radio works on radio waves and you must have heard it. The radio wave which you received has a different form than they actually are and this is why we can be called it as modulation.
Now the question is how it works, how much we need it and why do we need it?
We all know that most of the signal is in the form of sinusoidal. It carries information. The message signal which is transmitted from the station or source represents the original signal which is known as the band signal. Actually, in real life, no signal is in sinusoidal form. It spreads over a range of frequencies called signal bandwidth. But it must be sinusoidal. So to make it sinusoidal we need modulation and also to transmit signals over a long-range need modulation.
Again mixing of the signals is the main problem because a daily large number of signals are produced, transmitted and received. This signal would not be superimposed with other signals. If it is superimposed then our information will get corrupted and the receiver would not be able to receive it in good quality.
But it has some difficulties:
Size of the antenna or aerial. To transmit and receive signals we need a good antenna. Its wavelength must be quarter of wavelength. But practically it is not possible. But up to some extent we can do it by using modulation.
Mixing of the signal is a major issue on which we are still working. To achieve this, signals which are transmitted are superimposed on high-frequency waves called carrier waves. This process is known as modulation.

Note: You can remember this concept by taking examples of radio. Even our dish antenna. There are lots of uses of modulation and particularly frequency modulation. Low-frequency waves are transmitted on the high-frequency wave. This process is known as modulation. Basically, we just change the shape of a pulse which is in a signal.