Word synchronizer.

摘要

For establishing word synchronization between a data bit stream of N-bit words and the timing of syndrome calculation, a count value is incremented in response to the bit timing of the words and generating a hunting pulse (14a) for every count of N bits and a load timing pulse at every count of C bits. Syndrome calculation (11) is performed on the N-bit words in response to the hunting pulse to derive a syndrome when each of the N-bit words is out of synchronization with the timing of the calculation. The syndrome is latched (12) for a word interval and a first enabling signal (12b) is generated in response to the latching of the syndrome. Syndrome generating words are counted (13) to generate a second enabling signal (13a) when the count provides a valid indication that the word timing of the calculation is out of sync with the data hit stream. A copy of the hunting pulse is generated and delayed (15) for a period of M bits when the first and second enabling signals are simultaneously present (16) to cause syndrome calculation to be performed on the N-bit words, where the N and M integers are relatively prime and the integer C is smaller than integer M and greater than unity. The point of initialization is shifted for each syndrome calculation from one bit to another in search of the beginning of a word. Because of the "relatively prime" relationship of the integers N and M, all the bits of incoming data bit stream are examined in the search.