Modem for fading digital channels affected by multipath

摘要

A receiver designed for use in a mobile environment, which includes an adaptive equalizer driven by phase estimation and rotation circuitry, and which is operable in multipath fading channels. The present invention uses an AFC loop and a phase rotation circuit in front of the adaptive equalizer to improve equalizer performance in the fading channel. The present invention uses &pgr;/4 phase rotation circuitry before a phase quantization decision is made. This &pgr;/4 phase rotation circuitry allows for decisions to be made on a QPSK constellation, rather than on an input 8PSK constellation, thus improving detection performance.