METHOD AND APPARATUS FOR VITERBI DETECTION OF GENERALIZED PARTIAL RESPONSE SIGNALS USING PARTIAL MATCHED FILTER AND MATCHED FILTER METRICS

Methods and apparatus are provided for implementing high-speed and area efficient architectures for Viterbi detection of generalized partial response signals using both partial matched filter and matched filter metrics. In the method of the invention, branch metric terms are transformed to shift all time varying terms and some constant terms after an add compare select (ACS) unit. The total number of non-zero constants on trellis branches is minimized. The shifted time varying terms and the shifted constant terms are added directly to state metric terms. The time varying terms are expressed as outputs Zn of a partial matched filter or as outputs Wn of a matched filter. For a given generalized partial response target, the time-invariance property of the Viterbi detector enables identifying the minimum number of non-zero constants on trellis branches without resorting to heuristics. The time-invariance property holds for Viterbi detectors that process multiple samples per trellis-branch, thus allowing implementations at any desired speed.