Adaptive phase-insensitive amplitude demodulator for noncoherent DSBSC signals

The authors introduce an application for adaptive signal processing in noncoherent AM (amplitude modulation) detection of double-sideband-suppressed carrier (DSBSC) signals. The algorithm takes advantage of the tracking capability of gradient methods. The technique relies on the availability of both the modulated carrier signal in DSBSC form and the noncoherent reference carrier. The coefficients of the adaptive structure track the amplitude of the carrier and its quadrature component. Simulation results are presented to demonstrate the effect of the sampling frequency, the carrier frequency, the message frequency, and additive noise on the performance of the algorithm. The proposed approach appreciably reduces the hardware requirements compared to classical implementations. The realization requires only four multipliers, two adders, and two subtractors