Decision feedback equalizer including forward part whose signal reference point is shiftable depending on channel response
First Claim
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1. A decision feedback equalizer, comprising:
- first means for implementing linear equalization for an incoming signal, said first means including a transversal filter whose center tap is shifted by at least one symbol interval from a tap provided for the last stage of said transversal filter;
second means for implementing non-linear equalization for a signal applied thereto;
third means coupled to receive outputs of said first and second means for generating a difference signal between the outputs of said first second means;
fourth means coupled to receive the difference signal from said third means, said fourth means issuing a first error signal and a decision signal, said decision signal being applied to said second means;
fifth means coupled to receive said decision signal and coupled to receive signals appearing on said center tap and a tap provided in said last stage of said transversal filter, said fifth means correlating the received signals and monitoring a main response of channel impulse response of channel impulse response and a precursor; and
sixth means for receiving signals from said first and second means and also receiving said decision signal, said sixth means performing subtraction and generating a second error signal, said fifth means changing the distortion equalizing algorithms of said first means in accordance with signals received.
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Abstract
A center tap of a transversal filter, which forms part of a forward equalizer, is shifted by at least one symbol interval. An error signal is generated using a decision output and tap outputs of the forward and backward equalizers. An impulse response estimation circuit is provided to receive the decision output of the predetermined tap signals of the forward equalizer. The forward equalizer is controlled in accordance with the channel response to effectively achieve adaptive equalization.
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8 Claims
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1. A decision feedback equalizer, comprising:
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first means for implementing linear equalization for an incoming signal, said first means including a transversal filter whose center tap is shifted by at least one symbol interval from a tap provided for the last stage of said transversal filter; second means for implementing non-linear equalization for a signal applied thereto; third means coupled to receive outputs of said first and second means for generating a difference signal between the outputs of said first second means; fourth means coupled to receive the difference signal from said third means, said fourth means issuing a first error signal and a decision signal, said decision signal being applied to said second means; fifth means coupled to receive said decision signal and coupled to receive signals appearing on said center tap and a tap provided in said last stage of said transversal filter, said fifth means correlating the received signals and monitoring a main response of channel impulse response of channel impulse response and a precursor; and sixth means for receiving signals from said first and second means and also receiving said decision signal, said sixth means performing subtraction and generating a second error signal, said fifth means changing the distortion equalizing algorithms of said first means in accordance with signals received. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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Specification