Integrated services digital network (isdn) - private branch exchange, is capable of a synchronization of clock pulse generator to be selected automatically

摘要

Isdn (integrated services digital network) - private branch exchange, which is capable of automatically setting a synchronization of clock pulse generator to be selected, comprising:a plurality of priority - selection circuits, which are joined to one another in a priority switching of the linking are coupled for the transmission of a frame in a synchronous clock - output signal and a data clock - output signal;a plurality of long-distance network - chips, which with a network terminator via a remote network - interface is connected and further comprising a telephone exchange through the network terminator for receiving the frame in a synchronous clock - output signal and of the data clock - output signal is connected; anda plurality of subscriber - chips (18) which, with a terminal via a subscriber interface for receiving the frame in a synchronous clock - output signal and of the data clock - output identification signal is connected, characterized in that each priority - selection circuit has - of the priority selection circuits:a first not - gate (420), the one input terminal on the first not - gate (420) which has an actively - level of a layer 1 of a of the lt - t - chips (16) is applied, and an outlet connection of the first not - gate (420) having;a second not - gate (422), the one input terminal of the second not - gate (422) on which an authorization level - signal is applied, and..