Circuit arrangement for telecommunications switching systems with direct dialling

摘要

The circuit arrangement for identifying each calling subscriber according to the main patent ... (application P 3542405.2-31), in which the caller-end functional unit is divided into two sub-units, i.e. a line finder unit provided for the line finders and a group selector unit provided for the pulse group selectors is modified here in such a way that the step of a line finder is not transmitted from the line finder unit AS-E via the meter wire z-A to the group selector unit GW-E each time that it is re-adjusted, but rather a DC signal is obtained from the polling signal arriving in the group selector unit by means of a DC transmission circuit GS, which signal is transmitted via the meter wire z-A to the line finder unit where it is received by a corresponding receive circuit GE. A transmission circuit for AC voltages WS in the line finder unit transmits the audio-frequency AC voltages which contain the telephone numbers only when this signal arrives. The latter are fed in the group selector unit via a corresponding receive circuit WE into one winding OLÜ of the local line transformer. The group selector unit also has an audio receiver TE and the line finder unit has a receiver for meter pulses ZE. The dial pulses are also transmitted as DC signals from the group selector unit to the line finder unit.