Circuit arrangement for ascertaining operating conditions of subscriber stations of a time multiplex communication system

Claim 1

A COMMUNICATION SYSTEM, ESPECIALLY A TELEPHONE SYSTEM, WHEREIN TWO-WIRE CONNECTIONS ARE ESTABLISHED BETWEEN SUBSCRIBER STATIONS IN ACCORDANCE WITH THE TIME MULTIPLEX PRINCIPLE, COMPRISING LINE CIRCUITS RESPECTIVELY COOPERATIVELY CONNECTED WITH SUBSCRIBER STATIONS, MEANS FORMING A CALL MULTIPLEX POINT, ELECTRONIC CALL SWITCHES FOR CONNECTING WITH SAID CALL MULTIPLEX POINT, OVER THE RESPECTIVE LINE CIRCUITS, SUBSCRIBER STATIONS WHICH ARE TO BE INTERCONNECTED, MEANS FOR PRODUCING, UNDER THE CONTROL OF ADDRESSES OF SUBSCRIBERS INVOLVED IN THE EXTENSION OF A CALL, PHASE SHIFTED CONTROL PULSES FOR CONTROLLING THE OPERATIVE ACTUATION OF SAID ELECTRONIC CALL SWITCHES, THE RESPECTIVE PHASE SHIFTED PULSES BEING CYCLICALLY ALLOCATED TO THE CONNECTION WHICH IS TO BE ESTABLISHED BETWEEN THE INVOLVED SUBSCRIBER STATIONS, A COMMON CONTROL DEVICE, MEANS FOR INSERTING IN THE CYCLE OF SAID CONTROL PULSES A READING PULSE WITH A PULSE SEQUENCE FREQUENCY CORRESPONDING TO THAT OF THE CONTROL PULSES, MEANS GOVERNED BY SAID READING PULSE FOR SUCCESSIVELY TESTING ALL LINE CIRCUITS AS TO THE BUSY OR IDLE CONDITION OF THE RESPECTIVE SUBSCRIBER STATIONS AND THEREBY PRODUCING IN THE LINE CIRCUITS A CORRESPONDING CRITERION, MEANS FOR DIRECTLY EXTENDING CRITERIA TO SAID COMMON CONTROL DEVICE, AND MEANS IN SAID COMMON CONTROL DEVICE FOR EVALUATING A RECEIVED CRITERION AFTER COMPARISON OF THE ADDRESS OF THE CORRESPONDING TESTED SUBSCRIBER STATION WITH THE ADDRESSES OF SUBSCRIBER STATIONS WHICH ARE INVOLVED IN EXTENDED CALLS.