1. A method of recognizing a word containing a number of bits in a data stream, comprising: recirculating a known word in a first shift register clocked in a first direction; clocking said data stream through a second shift register in a direction opposite from said first direction; comparing each bit of the known word stored in a respective stage of said first shift register with a bit of said data stream stored in a corresponding stage of said second shift register; counting the number of comparing bits for each stage of registers during a plurality of clocking periods to determine if said word has been received in said data stream.