Synchronization apparatus in transmitting information on a simplex bus.

Synchronization apparatus in a telecommuni¬cation system of the TDM type in which information is transmitted in assigned time slots, in simplex data transmission between a plurality of equal transmitter/ receiver modules (A-N) connected to a common bus. The bus is divided into three sections, all transmitters (S) being successively connected to the first section (B1) and all receivers (R) being connected to the final section (B3) in the same order as the transmitters. The time delay between transmitters and bus is the same for all transmitters and constitutes a fixed value, whereby the total delay on the first section of the bus is determined by the number of transmitters connect¬ed. The same condition applies to the receivers so that the delay on the final section (B3) of the bus also is fixed value. The intermediate section (B2) of the bus extends from the last connected transmitter to the first connected receiver, and is variable in length such that in relation to the size of said fixed time delays it gives a selectable predetermined total time delay between transmitter and receiver in the same module. Each of the modules (A-N) contains a local clock oscillator (CL) common to the respec¬tive transmitter and receiver. Apart from internal clock signals, the oscillator also sends frame synchronizing pulses (FS) for synchronizing remaining modules (slave modules) each time the module is selected as the master. The synchronization pulses are sent once per frame and parallel to the data information from respective transmitter (S). With the aid of the ap¬paratus in accordance with the invention there is obtained a synchronization process enabling transmission of a first infor¬mation between an arbitrarily selected pair of modules and a second information between another arbitrarily selected pair of modules using two adjacent time slots without time difference between the sending sequences in the respective time slot.