In a receiver for signals with ISI the trial sequence of symbols which minimises an error function is considered to represent the original sequence

摘要

The present application is concerned with a receiver for receiving signals from a transmission channel which introduces inter-symbol interference (ISI). The receiver tries a number of trial binary sequences XSBn/SB and determines which of these sequences most accurately represents an originally transmitted sequence. This involves generating a value YSBn/SB, by passing the received signal through an integrator with integration time equal to the maximum time period over which one symbol can interfere with another, using a channel estimator to produce a sequence aSBn/SB representing the channel response, multiplying each element of the response sequence, aSBn/SB , with an element of a trial sequence, XSBn/SB , and subtracting YSBn/SB from the result to produce an error function ESBn/SB. The trial sequence which minimises ESBn/SB is considered to provide the most accurate representation of the transmitted sequence. Block decoding and sequential decoding embodiments are disclosed. The invention is preferably used with optically transmitted signals suffering from chromatic and/or polarisation dispersion.