Calculating apparatus and method for use in a maximum likelihood detector and/or decoder

摘要

A calculator for use in a maximum likelihood detector, including: a receiver for receiving convolution encoded data which may include noise; first calculator for calculating a first component of a first path metric difference between two possible sequences of states corresponding to the convolution encoded data, the two sequences each having a length equal to a constraint length of the convolution encoded data, and the two sequences starting at a same state and ending at a same state, adapted to calculate the first component using the convolution-encoded data and using convolution encoding parameters of the convolution-encoded data, wherein the first component is independent of the two sequences; and second calculator for calculating a second component of the first path metric difference using the two sequences, wherein the second component is independent of the convolution encoded data; and using the first and second components to obtain the first path metric difference.