Patent ID: 7065161

Claim:
A partial response maximum likelihood bit detection apparatus for deriving a bit sequence from an input information signal, comprising: an input for receiving the input information signal; a sampling unit for sampling the input information signal at sampling instants so as to obtain sample values of the input information signal at the sampling instants; and means for calculating, determining, establishing, outputting and repeating; the calculating includes calculating at a sampling instant for each of a plurality of states at the sampling instant, an optimum path metric value the determining includes determining for each of the plurality of states, a best predecessor state at the directly preceding sampling instant, a state at the sampling instant identifying a sequence of n subsequent bits, where n is larger than 3, and sequences of n subsequent bits having n 1 directly successive bits of the same binary value are allocated to the same state; the establishing includes establishing the best path from the state at the sampling instant having the lowest optimum path metric value, back in time towards a previous sampling instant via best predecessor states, established earlier or earlier sampling instants, to establish an optimum state at the previous sampling instant; the outputting includes outputting at least one bit of the n bits of the sequence of bits corresponding to the established optimum state at the previous sampling instant; and the repeating includes repeating the calculating, determining, establishing and outputting for a subsequent sampling instant.