AM demodulation - Walter Mulflur - Rhea

Synchronous Demodulation ->

  Assume that $ w_c > w_m  $ and consider the signal: 
     y(t)=x(t)$ cosw_c t $  
  The original signal can be recovered by modulating y(t) with the same sinusoidal carrier and applying a low pass filter to the 
  result.  
     w(t)=y(t)$ cosw_c $t 
         =x(t)$ cos^2 w_c $t
  Use the trig identity   
     $ cos^2 w_c $t=(1/2)+(1/2)$ 2cosw_c $t 
  We can rewrite as 
     w(t)=(1/2)x(t)=(1/2)x(t)$ 2cosw_c $t 
  In this process the demodulating signal is assumed to be synchronized in phase with the modulating signal.