Frequency Domain Analysis of Envelope Detectors for AM (DSB-LC) Signals

Amplitude modulation (AM) is a technique that relies on varying the amplitude of the RF carrier in accordance with the baseband signal. The signal is thus embedded in the carrier?s amplitude, and its spectrum becomes centered on the carrier frequency. The bandwidth of the modulated signal is double that of the baseband signal. To demodulate the AM signal, we adopt one of two possible detection approaches: coherent detection and noncoherent detection. Coherent detection relies on multiplying the received signal by a carrier identical to that used in the transmitter and then applying low-pass filtering to the resultant signal to extract the baseband signal. Noncoherent detection is carried out by tracing the envelope of the received signal to extract the baseband signal.