Question

how many types of modulation ? explain them .

Answer 1

there are three types of modulation =>
     i. frequency modulation - it is widely used for a variety of radio communications applications. it changes the frequency of the carrier a/c to signal information.
     ii. phase modulation -  it is most commonly used to convey digital signals. All high performance modems today use phase modulation. form of modulation that represents information as variations in the instantaneous phase of a carrier wave.
     iii.  amplitude modulation - is a technique used in electronic communication, most commonly for transmitting information via a radio carrier wave in which the amplitude of a carrier wave is varied in accordance with some characteristic of the modulating signal.

Answer 2

there are three types of modulation :-
  1- amplitude modulation - process to change the amplitude of carrier signals according to digital signal having information .
   2- frequency modulation - process to change the frequency of carrier signals according to digital signal having information .
   3- phase modulation - it is a process to change the phase of carrier signal according to digital signal having information .