DE1280345B - Circuit arrangement for monitoring the call and occupancy status of the subscriber lines checking devices in telecommunication systems, in particular telephone switching systems - Google Patents

Description

Circuit arrangement for monitoring the call and occupancy status the subscriber line testing facilities in telecommunications, in particular telephone switching systems The invention relates to a circuit arrangement for monitoring the call and Occupancy status of the subscriber line checking facilities in telecommunications, in particular telephone exchanges where for each subscriber line a magnetically saturable core is provided, its magnetization state both by a permanent pre-magnetization as well as by one of the call and occupancy status the subscriber station dependent and the permanent pre-magnetization rectified magnetization is determined, and where the examination of the state of magnetization of the cores takes place by interrogation pulses generated by means of a pulse generator.

It is known from German patent specification 1001336 to assign a -no to each subscriber line, which is magnetically saturated by a premagnetization and which is at least almost magnetically saturated in the opposite sense when the voltage of the subscriber line changes by the direct current flowing through a winding, and to provide a pulse generator which periodically feeds interrogation pulses to a core winding, which magnetize the core in the direction of the original bias. When a switch or selector is set on the subscriber line, the core is returned to its original magnetic state.

In this known arrangement, the subscriber line is in the call state periodic switching of the magnetization state of the subscriber line A core connected via a winding due to the applied interrogation pulses. A Part of the pulse energy is transferred to the subscriber line and can Give cause for disturbing phenomena.

It was also made, for example, by the German Auslegeschrift 1041098 known to measure the flow through the core due to a premagnetization in such a way that that just saturation is reached. Then by closing the participant loop The induced flow is rectified and shifted to the premagnetization the working point further into saturation. To check the call status Interrogation pulses applied to a core winding are opposite to the premagnetization and can only bring the operating point out of saturation if none there is additional flooding due to the closed participant loop. In the call state of the subscriber line, the operating point remains in the saturation range, so that with this known device no pulse currents in the subscriber line be induced. However, it must be disadvantageous in this known device be considered that in the event of failure of the test pulse generator all Subscriber lines are reported as in call because the core output streams fail.

This disadvantage can also be called when checking the occupancy Participant lines occur. It was published in the German Auslegeschrift 1168 499 known, in the speech state of the subscriber line, a winding of the associated core short-circuit, so that the interrogation pulses in contrast to the free state of the subscriber line do not cause a shift in the operating point between the saturation areas of the core can. A signal emitted by the test device "subscriber is busy" can therefore also come about incorrectly due to a fault in the pulse generator be.

The invention achieves that in the event of a malfunction of the Pulse generator, i.e. if the interrogation pulses are not received, the delivery of the state the subscriber lines characterizing signals is prevented, so that the emergence incorrect connections due to incorrect identification is avoided.

The invention is characterized in that one during the operating period of the pulse generator conductively controlled gate circuit is provided, the input of which to that which characterizes the magnetization state of the core being tested The device delivering the potential and its control input to the operating state of the pulse generator characteristic potential delivering output is connected to a facility.

The invention is explained using the circuit diagram. A core K is assigned to each subscriber line 1 a, 1 b. The permanent pre-magnetization supplied to it via its winding w 2 transfers it to the state of saturation. The subscriber line 1 a, 1 are connected to a further winding w 1 in a known manner, but only symbolically shown in the circuit diagram. If the loop is closed in the participant stables Tln, an additional flow is effected in the core K. In addition, after a switch S has been closed, interrogation pulses from a pulse generator JG are transmitted to a third winding w 3 of the core K via a transformer Tr.

In the embodiment shown, the after closing Additional magnetization generated by the subscriber loop rectified to the premagnetization, however, the magnetization generated by the interrogation pulses is directed in the opposite direction so that when the subscriber loop is open in a fourth winding w 4 output pulses be generated. However, after the subscriber loop has been closed, i.e. in the call state the subscriber station Tln, the output pulses are suppressed because the through the Inquiry pulses no longer caused the working point to exceed the saturation point of the core can bring out.

The winding w 4 is via a rectifier arrangement D 1 with the Base of a transistor T 1 connected. Output pulses control this conductive, like this that the potential of his. The collector becomes positive, while it does not Output pulse remains negative.

The interrogation pulses of the pulse generator JG, after being rectified in a diode D 2, control a further transistor T 2 to be conductive, so that it feeds a negative control potential to a gate circuit consisting of two diodes D 3, D 4 and a resistor R 1. The gate circuit is only permeable when the interrogation pulses are present and then forwards the potential characterizing the call or occupancy status of the subscriber station from the collector of the transistor T 1 to an output terminal P.

An interruption in the delivery of the interrogation pulses, for example as a result of opening the switch S or as a result of a malfunction, results in the gate circuit D 3, D 4, R 1 being blocked, so that the output terminal P is de-energized.

In the example shown, the pulse generator JG, the transformer Tr and the device T 2 can be used together for a larger number of monitoring devices.

The arrangement according to the invention is of course not only limited to the identification of calling subscriber stations, it is as well applicable to all types of switching equipment whose occupancy status is determined by the flow or non-flow of a feed current is indicated.

Claims (1)

Claim: Circuit arrangement for monitoring the call and occupancy status of the subscriber lines in telecommunication, in particular telephone rental systems, in which a magnetically saturable core is provided for each subscriber line, the magnetization state of which is due to both permanent pre-magnetization and a call and occupancy state of the Subscriber station-dependent magnetization rectified with the permanent pre-magnetization is determined, and in which the state of magnetization of the cores is checked by interrogation pulses generated by means of a pulse generator, characterized in that a gate circuit (D 3, D 4, R 1) is provided, the input of which is connected to the device (T1) which supplies the potential characterizing the magnetization status of the core (K) being tested, and the control input of which is connected to the operating status of the pulse generator (JG) characteristic potential supplying output of a device (T2) is connected.