Pulse or digital communications – Equalizers – Automatic
Patent
1995-06-02
1997-07-01
Tse, Young T.
Pulse or digital communications
Equalizers
Automatic
375290, 333 18, 360 65, 3647242, H03H 730, G11B 5035
Patent
active
056445954
ABSTRACT:
An improved adaptive three tap transversal equalizer for partial-response signaling. The invention reduces the complexity of the hardware, as well as reducing the sensitivity of the equalizer to gain and timing errors. The present invention employs an algorithm based on sample values around zero. The resulting decrease in average magnitude of the error results in decreased sensitivity to gain errors. The algorithm of the present invention improves cancellation of sample timing errors. In the present invention, the coefficient of an adaptive cosine equalizer is updated by integration of a stochastic gradient. To calculate the gradient, the product of the quantized output from the previous sample and the output from the present sample is summed together with the product of the output from the previous sample and the quantized output from the present sample. In addition, the equalizer output is masked such that values quantizing to non-zero values are discarded in the update algorithm. In systems employing separate adaptive loops for gain control, timing recovery and equalization, the amount of undesired loop interaction is much reduced from that of prior art methods.
REFERENCES:
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patent: 4575857 (1986-03-01), Murakani
patent: 5060088 (1991-10-01), Dolivo et al.
patent: 5067137 (1991-11-01), Kaneko
patent: 5175747 (1992-12-01), Murakami
patent: 5247541 (1993-09-01), Nakai
Pan Tzu-Wang
Yamasaki Richard G.
Brady III W. James
Donaldson Richard L.
Swayze, Jr. W. Daniel
Texas Instruments Incorporated
Tse Young T.
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