I've created a simulation on Matlab of amplitude modulation. After demodulating the signal I need to add a low-pass filter to remove the high frequency components.
I'm confused as to why this is? I though it was to get smooth out some of the additive white Gaussian nose I added, but surely that noise is added across all frequencies as its 'white' noise.
What is the need in filtering the demodulated signal and why is this needed before we can recover the signal?