Pulse or digital communications – Receivers – Interference or noise reduction
Patent
1996-04-04
1998-06-30
Tse, Young T.
Pulse or digital communications
Receivers
Interference or noise reduction
375233, 375290, 360 46, 360 65, H03K 512, H04B 314, G11B 509
Patent
active
057745056
ABSTRACT:
A signal processing channel and method for reducing intersymbol interference in a sequence of data symbols includes a pre-shaping filter for sharpening leading edges of data symbols and providing trailing edges that approximate a decaying exponential. The output of the pre-shaping filter is combined with a cancellation output from a resistance-capacitance circuit having a time constant selected to provide pulse responses that complement the exponentially decaying trailing edges. The combination of the shaped output and the cancellation output is input to a slicer or other decision device. The 2-level output from the slicer is an input to a decision feedback filter that generates the cancellation output. In addition to the resistance-capacitance circuit, the decision feedback filter includes a delay to properly time the coincidence of the cancellation output with the shaped output from the pre-shaping filter. Preferably, the signal processing channel and method include a gain circuit for setting the peaks of the shaped signals and include adaptive adjustment of the gain, the sharpening by the pre-shaping filter, and the RC time constant of the decision feedback filter.
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Croll Timothy Rex
Hewlett--Packard Company
Tse Young T.
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