Digital transmission system

摘要

A terminal for a telephone system and for receiving digital data in the form of a time multiplexed (TDM) data stream incorporating frames appearing at a predetermined frame period and each frame incorporating a frame word. The terminal comprises a frame word detecting circuit (52) for detecting frame words; an alignment detecting circuit (53, 55, 56) for determining whether a received TDM data stream is in alignment or not; a search circuit (53, 55, 56, 57, 59, 60) for initiating a bit-by-bit search of the incoming data stream for the sequence of bits forming the frame word when an "out-of-alignment " condition has been detected by the said alignment detecting circuit; and a delay circuit (58) for delaying the start of the bit-by-bit search after an "out-of-alignment" condition has been detected.