Exchange for a meshed telecommunications network

摘要

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.