in the process of sampling an analog signal g(t) is multiplied by a periodic train of rectangular pulses c(t)each of unit area ,given that the pulse repetition frequency of this periodic train is fs and the duration of each rectangular pulse is T (with fsT<<1) , do the following :
a- find the spectrum of the signal s(t) that result from the sampling process you may assume that t=0 correspond to the midpoint of a rectangular pulse in c(t)
b- show that the original signal g(t) may be recovered exactly from its sampled version provided that the conditions embodied in the sampling theorm are satisfied.