Partial response maximum likelihood (prml) bit detection apparatus

Abstract

Sample values of an input information signal are obtained at sampling instants. For each of a plurality of states at a sampling instant, an optimum path metric value is determined. For each of the plurality of states a best predecessor state at he directly preceding sampling instant is determined. A state at the sampling instant identifies 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 ar allocated to the same state. The best path is established 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 for earlier sampling instants, to establish an optimum state at the previous sampling instant. Then at least one bit of the n bits of the sequence of bits corresponding to the established optimum state at the previous sampling instant is output.