Synchronization related to data streams

The improvement in a remote terminal comprising a primary distribution unit for exchanging information with a central office, a plurality of secondary distribution units for exchanging information with telephone sets of customers at remote locations from said terminal, and information transfer facilities interconnecting said primary unit and secondary units to implement exchange of information through said primary unit and secondary units between said central office and said telephone sets via first time division multiplex data streams transmitted from said primary unit to each of said secondary units, and via second time division multiplex data streams transmitted from each of said secondary units to said primary unit, each of said time division multiplex data streams being constituted of periodic consecutive binary bits and having the format of a plurality of periodic frames of time slots of which each of said frames comprises a service slot for only service bits and a plurality of customers slots for customer bits and a lesser number of service bits, and said improvement comprising:

• a first plurality of encoding means each incorporated in said primary unit and respectively corresponding to said first data streams and each operable on the corresponding first stream to generate in each of the frames therein both a synchronizing pattern of reserved service bits comprising a sequence of synchronizing bits in the service slot of such frame and, also, a spoiler pattern of reserved service bits comprising spoiler bits in customer slots of such frame, said spoiler pattern being interrelated with said synchronizing pattern to preclude any bit sequence present in the last named stream and including any customer bit from duplicating said synchronizing pattern, a first plurality of decoding means incorporated said primary unit and respectively corresponding to said second data streams and operable to detect the binary values of the bits therein, each such decoding means in said first plurality thereof being responsive to and only to detection thereby of the presence in the corresponding second data stream of a full synchronizing pattern to produce a synchronizing signal utilized by the primary unit, a second plurality of encoding means respectively corresponding to and incorporated said secondary distribution units and operable in the same manner as said encoding means in said first plurality thereof to generate synchronization and spoiler patterns in the second data streams transmitted from said secondary units to said primary unit, and a second plurality of decoding means respectively corresponding to and incorporated in said secondary distribution units and each operable in the same manner as said decoding means in said first plurality thereof to be responsive to and only to the presence of a full synchronizing pattern in the first data stream reaching the secondary distribution unit corresponding to that decoding means to produce a synchronizing signal utilized by that secondary distribution unit.

Apparatus comprising, a circuit card usable in equipment in a telecommunications network for conveying information of customers thereof, circuitry on said card to receive and process data and to forward it in the form of an outgoing time division multiplexer stream of periodically recurring consecutive binary valued digital bits, said stream having the format of periodic flames of time slots of which each frame consists of a service time slot comprising service bits, and, also, of a plurality of customer time slots each consisting of customer bits for carrying customer information and of a lesser number of service bits, and encoding means mounted on said card and in the form of a semiconductive integrated circuit, said encoding means being responsive to local synchronizing signals derived from said received data to generate in said stream both a synchronizing pattern comprising the binary values of a sequence of service bits in said service slot and reserved for such pattern and, also, a spoiler pattern comprising the binary values of a plurality of spoiler service bits which are respectively distributed over and included in said plurality of customer slots and are reserved for said spoiler pattern, said synchronous pattern and spoiler pattern being interrelated to prevent any bit sequence in said stream which includes any customer bit from fully duplicating said synchronization pattern.