Method and apparatus for synchronizing a clock of a telecommunication switching system. The clock of the telecommunication switching system is supplied, at least at times, with reference clock signals from a plurality of external reference clock sources. Every external reference clock source has a predetermined priority allocated to it. The supplied reference clock signals are checked for clock errors to which individual errors are allocated. For synchronization, the clock accepts an external reference clock signal dependent on the priorities allocated to the reference clock sources and dependent on the clock-error-associated error values. In an initialization, initial error values are allocated to the reference clock sources. In a re-initialization of the system, the synchronization procedure is continued from the current error values that are present at the time of the system outage.

Method and apparatus for the synchronization of a clock means of a telecommunication switching system

A clock circuit of a telecommunication switching system is supplied with reference clock signals from a plurality of external reference clock sources at least from time to time. Each external reference clock source is allocated a predetermined priority. The reference clock signals supplied are checked for clock errors which are allocated individual errors. For its synchronisation, the clock circuit accepts an external reference clock signal in dependence on the priorities allocated to the reference clock sources and on the clock-error-individual error values. During an initial commissioning, initial error values are allocated to the reference clock sources. During a recommissioning of the system, the synchronisation method is continued on the basis of current error values available at the time of system failure.

Method and apparatus for synchronising a clock-circuit of a switching communication system

The invention relates to a system and to a method for introducing redundancy mechanisms into a communication system by way of the following steps: a) transmitting a data telegram for synchronization from a clock system to the nodes via disjunctive paths, b) if transmission in one of the disjunctive paths is disrupted: i) transmitting the data telegram from the clock system via a first section of the disrupted path, and ii) transmitting the data telegram from the clock system via the not-disrupted path and from there via a second section of the disrupted path.

System and method for introducing redundancy mechanisms into a communication system

The phase positions of the frame timing data (RT1, RT2 ...) of incoming data signals are found to initialise a frame timing for data signals. The phase of the system timing (RTN) can be regulated on any item of frame timing data. To this end the phase positions (P1, P2, ...) of all incoming frame timing data are measured (PMN) and stored (SPN). In the event of interference or breakdowns, a return is made to the previously stored phase positions in order to maintain constant phase relations. The invention is particularly applicable to centralised multi-station control signals or common-frequency radio.

Process for initialising a frame timing and arrangement and use

If the exchange selected as master clock generator is taken out of operation in a meshed telecommunications network, the remaining exchanges must look for a new master clock generator. During this search process, each exchange must operate with its own clock source. Since the clock sources of the individual exchanges are now no longer synchronised with one another, this mandatorily leads to information losses when messages are exchanged between the individual exchanges. The newly designed exchange should provide for fast synchronisation of the clock source to a master clock and ensure that the telecommunication network operates as faultlessly as possible in the event of disturbances in the telecommunications network. For this purpose, a clock recovery unit with two outputs is provided in the exchange for each other exchange connected to it, which clock recovery unit outputs at a first output a clock signal regenerated from received data and, in the event of a non-regenerable clock signal, a clock failure signal at a second output; each output can be supplied via a switching means to the clock source, the switching means being controllable by a priority discriminator, and the first outputs of the clock recovery unit are supplied to a synchronisation input of the clock source and the second outputs of the clock recovery unit are supplied to an integration time change-over switch arranged in the clock generator.

Gert Dipl Ing Belsemeyer

Papers

Exchange for a meshed telecommunications network