Modem for fading digital channels affected by multipath

Details Modem for fading digital channels affected by multipath Modem for fading digital channels affected by multipath

1991-06-17

1994-05-10

Chin, Stephen

Pulse or digital communications

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Testing

375 80, 375 86, 375 96, 375 97, 329304, H03H 730

Patent

active

053115457

ABSTRACT:
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 .pi./4 phase rotation circuitry before a phase quantization decision is made. This .pi./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.

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