Modulation and its Necessity
Modulation is the method of changing the carrier signal in according to the message signal.The high-frequency sin wave signal is known as carrier signal in the process of modulation.That output signal is called as modulating signal.Modulation is a process which making a change of shift at the range with frequencies of signal.
Types of modulation
A sinusoidal carrier wave can be expressed as
Its three distinct characteristics are :
|(ii)||angular frequency (ωc)|
|(iii)||phase angle (θ).|
Either of these three characteristics can be varied in accordance with the modulating signal. These result in three types of modulation.
|(i)||Amplitude modulation (AM)|
|(ii)||Frequency modulation (FM)|
|(iii)||Phase modulation (PM)|