Angle Modulation

Angle modulation varies the angle of a carrier wave according to the amplitude of the modulating baseband signal (the message signal). The amplitude of the carrier is kept constant. Phase modulation and frequency modulation are particular types of angle modulation.

Angle modulation can be expressed using the following equation:

where

A_c is the carrier amplitude
f_c is the carrier frequency
k_f is the frequency deviation constant in Hz/V
f_m is the frequency of the message signal