effect of noise on analog signals?

Question

effect of noise on frequency , amplitude and phase modulation systems

Answer 1

Generally the noise is considered as an additive signal. Therefore it directly affects only the amplitude of the useful signal. However, since the noise has unpredictable phase, it (through the affected amplitude) indirectly affects the phase and consequently the frequency of the useful signal. However, the effect on the phase and frequency is generally much less than the effect on the amplitude. That's why the FM radio signal is much better than AM.

Answer 2

Depends on the noise. General noise only affects amplitude, which is why FM radio is so much better than AM.