Abstract: Synchronization apparatus in a telecommunication 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 connected. The same condition applies to the receivers so that the delay on the final section (B3) of the bus also is fixed value.