Or correction of synchronisation faults for a switchable data transmission network operating on a time sharing basis

Claim 1

A switchable system for transmission of data words carrying digital information wherein the transmission lines are timesharing transmission lines comprising time slots grouped in frames, the said frames being identified by synchronizing words or bits in their leading time slot, and the exchanges are timesharing exchanges wherein the clocks are asynchronous and drift with respect to each other, which in the transmission of datacarrying words introduce repetitions or omissions of synchronizing words and of data-carrying words and retardation or advances by one time slot of the data-carrying words caused by the slot jumps generated in the local exchange when the drift between the clock of the distant exchange originating the datacarrying words and the clock of the local exchange becomes equal to the duration of a time slot of the local clock, the said system comprising means situated at the distant exchange for the transmission of blank words, along each transmission channel and between data-carrying words; first, second and third shift registers situated in cascade at the local exchange, and chronologically staggered with respect to each other by the period of one time slot and adapted to receive the data coming from the distant exchange including blank words; means for scanning the data words carrying digital information; and means for selectively connecting the said scanning means to the said shift registers, the said connecting means rendering it possible to shift from the first shift register to a second shift register in the lead by the period of a time slot over the said first register when a repetition of a synchronizing word is introduced by a slot jump in such manner as to eliminate this repetition, and at each beginning of a frame and to shift from the first shift register to the third shift register trailing by the period of one time slot behind the said first register when an omission of a synchronizing word is introduced by a slot jump in such manner as to cancel this omission, and at each beginning of a frame, and to shift from the said third register to the said first register each time a blank word is received.

Claim 3

A system for the switchable transmission of data words carrying digital information wherein the transmission lines are time sharing lines comprising time slots grouped into frames, the said frame being identified by synchronizing words in their leading time slot, and the exchanges are time sharing exchanges wherein the clocks are asynchronous and drift with respect to each other, which in the transmission of data carrying words introduces repetitions or omissions of synchronizing words and of data-carrying words caused by slot jumps produced in the local exchange when the drift between the clock of the distant exchange and the clock of the local exchange becomes equal to the duration of a time slot of the local timer, the said system comprising a plurality of buffer registers intended to receive the words with addresses equal to the sequence number of the time slot they occupy within the frame an address register controlling the addresses of the words received; means for correcting the sequence of addresses supplied by the said address register by repeating the address of a synchronizing word when a repetition occurs of the said synchronizing word as a result of a slot jump and by omitting the address of a synchronizing word when an omission occurs of the said synchronizing word; means situated at the exchange for the transmission of blank words on each transmission line between data-carrying words, three shift registers situated at the local exchange, grouped in cascade, chronologically staggered with respect to each other by the period of a time slot and adapted to receive the data coming from the distant exchange; means for selectively connecting the said buffer registers to the said shift registers, the said connecting means rendering it possible to shift from a first shift register to a second shift register in the lead by the period of a time slot over the said first register when a repetition of a synchronizing word is introduced by a slot jump in such manner as to eliminate this repetition and at each beginning of a frame, and to shift from the said second register to the first register each time a blank word is received on a line, and to shift from the first shift register to the third shift register trailing by the period of a time slot behind the said first register when an omission of a synchronizing word is introduced by a slot jump in such manner as to cancel this omission and at each beginning of a frame, and to shift from the said third register to the said first register each time a blank word is received on a line; and means of increasing by one unit the address of a word supplied by the said address register when the buffer register which is the destination of the said word is connected to the said second register, and of decreasing by one unit the address of a word supplied by the said address register when the buffer register which is the destination of the said word is connected to the said third register.

Claim 4

A system for the switchable transmission of data words carrying digital information wherein the transmission lines are time sharing lines comprising time slots grouped into frames, the said frame being identified by synchronizing words in their leading time slot, and the exchanges are time sharing exchanges wherein the clocks are asynchronous and drift with respect to each other, which in the transmission of data carrying words introduces repetitions or omissions of synchronizing words and of data-carrying words caused by slot jumps produced in the local exchange when the drift between the clock of the distant exchange and the clock of the local exchange becomes equal to the duration of a time slot of the local timer, the said system comprising a plurality of buffer registers intended to receive the words with addresses equal to the sequence number of the time slot they occupy within the frame an address register controlling the addresses of the words received; means for correcting the sequence of addresses supplied by the said address register by repeating the address of a synchronizing word when a repetition occurs of the said synchronizing word as a result of a slot jump and by omitting the address of a synchronizing word when an omission occurs of the said synchronizing word; means situated at the exchange for the transmission of blank words on each transmission line between data-carrying words, three shift registers situated at the local exchange, grouped in cascade, chronologically staggered with respect to each other by the period of a time slot and adapted to receive the data coming from the distant exchange; means for selectively connecting the said buffer registers to the said shift registers, the said connecting means rendering it possible to shift from a first shift register to a second shift register in the lead by the period of a time slot over the said first register when a repetition of a synchronizing word is introduced by a slot jump in such manner as to eliminate this repetition and at each beginning of a frame, and to shift from the said second register to the first register each time a blank word is received on a line, and to shift from the first shift register to the third shift register trailing by the period of a time slot behind the said first register when an omission of a synchronizing word is introduced by a slot jump in such manner as to cancel this omission and at each beginning of a frame, and to shift from the said third register to the said first register each time a blank word is received on a line; and means of increasing by one unit the address of a word supplied by the said address register when the buffer register which is the destination of the said word is connected to the said second register, and of decreasing by one unit the address of a word supplied by the said address register when the buffer register which is the destination of the said word is connected to the said third register.