Question

explain amplitude modulation with block diagram, and woking of A.M. receiver.

Answer 1

AM modulation is multipliation of the signal with some carrier signal whose frequency is much larger than the maximum frequency of the signal. \[y(t) = \cos \omega t*\cos \omega _{c}t=(1/2)(\cos(\omega+\omega_{c})t + \cos(\omega-\omega_{c})t )\]
Demodulation is basically multiplication by the same carrier frequency signal followed by low pass filtering. It becomes easily understood when signals are represented in frequency domain and multiplication becomes convolution.