Co-channel interference rejection using a model-based demodulator for AMPS and NAMPS

Co-channel interference is a major problem that limits the cell capacity in AMPS systems. For a digital implementation of an AMPS receiver, a quadrature demodulator would typically be used. This paper details the development of a demodulator that uses model-based frequency estimation to demodulate the frequency-modulated AMPS signal. This new technique shows improved performance in the presence of cochannel interference. Additionally, this technique has been used to develop a class of extensions for a conventional quadrature demodulator that provide improved performance in the presence of channel noise.