Pulse or digital communications – Equalizers – Automatic
Reexamination Certificate
2006-12-26
2006-12-26
Bocure, Tesfaldet (Department: 2611)
Pulse or digital communications
Equalizers
Automatic
C375S359000
Reexamination Certificate
active
07154946
ABSTRACT:
An equalizer for return-to-zero (RZ) signals comprises: (a) an equalizer core for equalizing the received signal; (b) a decision corrector for detecting and correcting misplaced pulses and double pulses in the equalized signal using known characteristics and properties of the RZ signal itself; and (c) an error calculator that generates an error signal for updating tap values based on the initial outputs of the equalizer core and the corrected outputs of the decision corrector. The decision corrector comprises a zero assertion counter that generates a clock synchronized with the timing of the received signal, and corrects the equalized signal by forcing zeroes in those portions of the equalized signal that the synchronized clock indicates should be “RZ” zeroes (as opposed to “data” zeroes or “data” symbols “1” or “−1”). The decision corrector further comprises a misplaced pulse detector for detecting misplaced pulses and double pulses based on both the output of the zero assertion counter and coding in the RZ signal, and corrects the equalized signal by moving the misplaced pulse or doubled portion of the pulse forward or backward in time in accordance with the principles of the RZ coding scheme used. The equalizer can further comprise interpolators for generating a plurality of signals based on the equalized signal, to provide a greater diversity of information for the decision corrector.
REFERENCES:
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Xiong, F.Digital Modulation Techniques, Artech House, 2000.
ITU-T Recommendation G. 775—“General Aspects of Digital Transmission Systems: Loss of Signal (LOS) and Alarm Indication Signal (AIS) Defect Detection and Clearance Criteria”, 1994.
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Telecordia (Bellcore) GR-499-CORE—“Transport Systems Generic Requirements (TSGR): Common Requirements”, Dec. 1995.
Katic Ognjen
Rey Claudio Gustavo
Bocure Tesfaldet
Oyen Wiggs Green & Mutala LLP
PMC-Sierra Inc.
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