A method and circuit arrangement in order to achieve a frame synchronisation in a pcm - receiving device of a pcm - time division multiplexing - telecommunication network

摘要

Frame synchronization is achieved in a pulse code modulation receiver, including a receiving counter, of a pulse code modulation time division multiplex telecommunications network in response to receipt of frame synchronizing signals which occur in each m-th of the pulse frames on which the telecommunications system is based. A hunting process is carried out during a synchronizing time interval following the occurrence of frame synchronizing the signals at intervals of m pulse frames and in response to such occurrence a receiving counter is synchronized. The contents of the time sections in which the frame synchronizing signals can occur are stored for a period of m-l pulse frames, along with the time section contents of corresponding time sections of preceding and following pulse frames. The stored contents are logically checked m-l times to determine if the frame synchronizing signals occur only once within m pulse frames in corresponding time sections and, upon a positive result of said checking, a result signal is entered into a circulating memory and circulated over an interval of one pulse frame and renewed and circulated one pulse frame later in response to a corresponding positive result. Upon the absence of a positive result, the result signal is erased from the circulating memory. The receiving counter is reset when, during an interval of one pulse frame, only one entry has been made in the circulating memory. The steps are repeated after setting of the receiving counter beginning with the next first entry into the circulating memory.