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 :
| i) | Amplitude (Ec) |
| (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) |