Partial response maximum likelihood (prml) bit detection apparatus

Abstract

A partial response maximum likelihood (PRML) bit detection apparatus derives a bit sequence from an input information signal. The apparatus includes: input apparatus for receiving the input information signal; sampling apparatus for sampling the input information signal at sampling instants so as to obtain samples of the input information signal at the sampling instants; conversion apparatus for converting an array of the samples into an array of bits of a first or a second binary value, detection apparatus for repeatedly detecting a state for subsequent sequences of n subsequent bits of the array of bits, the subsequent sequences being obtained by shifting a time window of n subsequent bits each time over one bit in time; apparatus for establishing the best path through the states; and deriving apparatus for deriving a sequence of bits in accordance with the best path through the states. In accordance with the invention, 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. In a specific embodiment is n an odd number larger than 4. Now, sequences of n subsequent bits having n−2 directly successive bits of the same binary value as the central n−2 bits in such n-bit sequence, are allocated to the same state. This results in an a PRML detection apparatus with reduced complexity.