15.8 A MPLITUDE M ODULATION

. A MPLITUDE M ODULATION In amplitude modulation the amplitude of the carrier is varied in accordance with the information signal. Here we explain amplitude modulation process using a sinusoidal signal as the modulating signal. Let c(t) = A c sin , c t represent carrier wave and m(t) = A m sin , m t represent the message or the modulating signal where , m =  f m is the angular frequency of the message signal. The modulated signal c m ( t ) can be written as c m (t) = (A c + A m sin , m t) sin , c t c c c A A sin t sin t A       ( . ) Note that the modulated signal now contains the message signal. This can also be seen from Fig. . (c). From Eq. ( . ), we can write, ( ) c c c c c t A sin t A sin t sin t  ( . ) Modulation and Demodulation labs.com/ .htm