Pulse or digital communications – Receivers – Particular pulse demodulator or detector
Patent
1993-10-29
1995-11-14
Coles, Sr., Edward L.
Pulse or digital communications
Receivers
Particular pulse demodulator or detector
375229, 375254, H03D 100
Patent
active
054673747
ABSTRACT:
A low complexity adaptive equalizer for use in U.S. digital cellular radios demodulates .pi./4-shifted differentially encoded quadrature phase shift keyed (DQPSK) encoding in the presence of intersymbol interference (ISI) with reduced decoding complexity by employing an estimated received constellation which takes into account channel changes over time and ISI. The decoding complexity is reduced by tracking a reduced number of estimated reference constellation points and taking advantage of the geometry to estimate the remaining symbol constellation points. A slot of symbols is decoded, employing unique filtering, in segments from the beginning in a forward direction and from the end in a reverse direction meeting at a fade point. This isolates a fade and allows the equalizer to perform more reliably.
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Chennakeshu Sandeep
Dent Paul W.
Koilpillai Ravinder D.
Toy Raymond L.
Coles Sr. Edward L.
General Electric Company
Nguyen Madeleine
Snyder Marvin
Zale Lawrence P.
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