Inventors:
John A. C. Bingham - Palo Alto CA
Jack H. Kurzweil - San Jose CA
Assignee:
Racal-Vadic, Inc. - Sunnyvale CA
International Classification:
H04B 304
Abstract:
Disclosed is a constrained adaptive equalizer for use in a digital communication system receiver combining transversal and decision feedback equalization techniques. The constrained adaptive equalizer uses a constraint on the taps of the tranversal section of the equalizer which has both leading and lagging taps. These constraints force the transversal equalizer to correct only the leading echoes of a received digital signal in a communication system and treat them as if they resulted only from phase distortion. The constrained adaptive equalizer minimizes noise amplification while reducing intersymbol interference. The transversal segment of the constrained adaptive equalizer approximate the phase equalizer by constraining its multiplying coefficients i. e. taps, in accordance with the symmetry of the differential delay characteristic of the transmission medium around a signal carrier frequency. This constrained transversal decision feedback equalizer combination can be used for either passband or baseband equalization and for either complex signals, such as QAM signals, or real signals, such as baseband or single side band signal.
