Method and apparatus for detecting a frame alignment word in a data system

Apparatus for error-tolerantly detecting a multi-bit frame alignment word in a time division multiplex data stream of bits despite corruption of the frame alignment word due to bit transmission errors, comprising:

• storage means for serially receiving, storing and outputting the data stream of bits;
• matching means having a preset bit pattern corresponding to the frame alignment word to be detected, said preset bit pattern being comprised of a predetermined number of groups of bits, said matching means being connected to the storage means for serially receiving and comparing the data stream of bits from the storage means with the groups of bits of the preset bit pattern, and for generating a group output signal from each group when the bits from the data stream match a respective group;
• and
• decoder means connected to the matching means for receiving each group output signal, and for generating a frame alignment signal indicative of detection of the frame alignment word when a specified number, less than said predetermined number, of groups have generated group output signals.