In amplitude madulation, the instantaneous
voltage of carrier waves is varied by the
instantaneous voltage of modulating waves. On
transmission through a channel, noise signals
can also be added, resulting in change in the
amplitude of modulated wave. Due to it, the receiver receives the modulating signal having
a part of noise.
However, in frequency modulation, the
frequency of carrier waves is changed as per
instantaneous voltage of modulating waves. This
can only be done at the mixing or modulating
stage and not while signal is transmitted in
channel. Hence, noise does not affect FM signal.
That is why FM signal is less susceptible to noise than an AM signal .
