Unique word detector and method for detecting a unique word within one of several windows offset in time

摘要

A unique word detector for use in detecting a unique word received by a demodulator in one of a plurality of windows offset in time is provided. The unique word detector includes a correlator for receiving successive sequences of binary data related to one of the windows. The correlator compares each of the successive sequences with the unique word to generate a measure of correlation between the sequences of binary data and the unique word. The unique word detector also includes a window detector interfaced with the correlator for comparing each of the measures of correlation to a predetermined threshold to determine whether the unique word has been received. A method of detecting the unique word in one of the windows is also provided. According to the method a predetermined number of successive measures of correlation are accumulated to form a first cumulative correlation value related to one window and the same number of successive measures of correlation are accumulated relating to a later window to form a second cumulative correlation. The first and second cumulative correlation values are compared to each other to identify in which of the plurality of windows the unique word has been detected.