Amplitude Modulation

modulation is defined as the process by which some characteristics of a carrier wave is varied in accordance with a modulating signal. The baseband signal is referred to as the modulating signal and the output of the modulation process is called as modulation signal. Amplitude Modulation index = Emax - Emin/Emax + Emin Emax = Maximun peak to peak value of modulated signal Emin = Minimum peak to peak value of Modulated signal Envelope Detector In the positive half of the i/p signal, the capacitor C charges up to the peak voltage of the i/p signal as the input fails below this voltage, the diode is off because Vcc is greater than Vi. The capacitor discharges through R during -ve cycle. The capacitor discharges slowly during cutoff and hence Vc charges negligibly. Thus, during each cycle, C charges up to new peak.