What is modulation? Explain the types of modulation with necessary diagrams.

Explanation

Modulation: For long distance transmission, the low frequency baseband signal (input signal) is superimposed onto a high frequency radio signal by a process called modulation। There are 3 types of modulation based on which parameter is modified। They are (i) Amplitude modulation, (ii) Frequency modulation, and (iii) Phase modulation।
(i) Amplitude Modulation (AM): If the amplitude of the carrier signal is modified according to the instantaneous amplitude of the baseband signal, then it is called amplitude modulation। Here the frequency and the phase of the carrier signal remain constant। Amplitude modulation is used in radio and TV broadcasting The signal shown in figure (a) is the message signal or baseband signal that carries information figure (b) shows the high frequency carrier signal and figure (c) gives the amplitude modulated signal। We can see clearly that the carrier wave is modified in proportion to the amplitude of the baseband signal।