JPH0213055A - Subscriber circuit - Google Patents

Abstract

PURPOSE:To avoid the normal action of a subscriber circuit from being blocked for a long time due to the mixed contact of a subscriber line by detecting a difference between the voltage of both terminals of a resistance of a grounding side and the voltage of both terminals of the resistance at a power source side and outputting it as the mixed contact detection result of the subscriber line. CONSTITUTION:In a condition in which the mixed contact is not generated and a feeding is normally executed, the voltage is supplied to an A line 2, a grounding is supplied to a B line 3, an equal current flows to constant resistances 6 and 7 having the same resistance value, and thereby, the voltages of both terminals of the two constant resistances are equal. When the B line 3 of the subscriber line is mixed- contacted, the current to flow to the constant resistance 7 is made larger than the current to flow to the constant resistance 6, and the voltage of both terminals of the constant resistance 7 is made larger than the voltage of both terminals of the constant resistance 6. At such a time, a comparator 13 outputs a positive voltage as the difference between two voltages. A comparator 14 outputs a comparison result between the voltage and a negative voltage, and a high order control device is informed that the mixed contact is generated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention detects interference in subscriber lines and controls fffl
It concerns the subscriber circuit of the telephone exchange that notifies the equipment.

[Conventional technology]

The subscriber circuit of a conventional telephone exchange has a cross-contact protection circuit in its power supply circuit, and in the event of a cross-contact between the subscriber lines, this protection circuit operates to prevent the subscriber circuit from being destroyed. .

[Problem to be solved by the invention]

However, although such conventional subscriber circuits are equipped with a 3W cross-contact protection circuit, they do not have a function of notifying the subscriber circuit control device of a cross-contact condition on the subscriber line. Therefore, even if cross-contact occurs, the higher-level control device is unable to recognize it and take appropriate measures, and the cross-contact protection circuit is activated all the time, disrupting the normal operation of subscriber circuits for a long period of time, and causing subscriber Not only was there a risk of circuit damage, but it also led to a decline in service to subscribers.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a subscriber circuit capable of eliminating such drawbacks, detecting the occurrence of subscriber line interference, and notifying a higher-level control device.

[Means to solve the problem]

The present invention relates to a switch circuit that is connected to a subscriber terminal by the A line and B line of a two-wire subscriber line and switches the polarity of the voltage applied between the A line and the B line, and the switch circuit. In a subscriber circuit of a telephone exchange, the subscriber circuit includes a power supply circuit that supplies earth air through a first resistor and voltage through a second resistor, and monitors the loop condition between the A line and the B line. Voltage difference detection means for detecting the difference between the voltage across the first resistor and the voltage across the second resistor, and comparing the difference between the two voltages detected by the voltage difference detection means with a predetermined voltage. The present invention is characterized in that it includes a comparator that outputs the result as a detection result of subscriber line cross-touch detection.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block circuit diagram showing one embodiment of a subscriber circuit according to the present invention. This subscriber circuit is connected to a subscriber terminal l by a two-wire subscriber line A line 2 and a B line 3.
A switch circuit 4 that switches the polarity of the voltage applied between the wire 2 and the B wire 3, and a constant resistor 7 (
The voltage VIIB is supplied by a battery through a constant resistor 6 (resistance r) and a transistor 8, and the loop state between the A line 2 and the B line 3 is monitored. It includes a power supply circuit 5 and a contact detection and display circuit 10 that notifies a higher-level control device of contact of subscriber lines.

The comparator 11 of the contact detection display circuit 10 has a constant resistance 6
The comparator 12 detects the voltage across the constant resistor 7. Comparator 13 is composed of these two comparators 11
．． The outputs of 12 are compared, and the difference between the voltage across constant resistor 6 and the voltage across constant resistor 7 is detected. The output voltage is positive when the voltage across the constant resistor 7 is larger. Here, the comparators 11.1213 constitute voltage difference detection means. The comparator 14 compares the output of the ratio 1 calibrator 13 inputted to its negative input terminal with a predetermined negative voltage manually applied to its positive input terminal, and outputs the result to the upper control device. .

Next, the operation will be explained. When power is being supplied normally without any contact, voltage is supplied to the A line 2, earth air is supplied to the B line 3, and equal current flows through the constant resistors 6° and 7, which have the same resistance value. The voltages across these two constant resistors are equal. Therefore, the detected values of the comparators 11 and 12 are equal, and the difference between the voltage across the constant resistor 6 and the voltage across the constant resistor 7 detected by the comparator 13 is zero. The comparator 14 then outputs the comparison result between the zero volt voltage and the negative voltage, and notifies the higher-level control device that no cross contact has occurred.

Now, for example, if the B line 3 of the subscriber line is crossed, the current flowing through the constant resistor 7 will be greater than the current flowing through the constant resistor 6, and the voltage across the constant resistor 7 will be greater than the voltage across the constant resistor 6. Become. At this time, the comparator 13 outputs a positive voltage as the difference between these two voltages. The comparator 14 outputs a comparison result between this voltage and a negative voltage, and notifies the higher-level control device that contact has occurred.

〔Effect of the invention〕

As explained below, the present invention provides a switch that is connected to a subscriber terminal by the A line and B line of a two-wire subscriber line and switches the polarity of the voltage applied between the A line and the B line. and a power supply circuit for supplying earth air through a first resistor and voltage through a second resistor to the switch circuit, and monitoring the loop condition between the A and B wires. In the subscriber circuit of the TA machine, there is a voltage difference detection means for detecting the difference between the voltage across the first resistor and the voltage across the second resistor, and a voltage difference detection means for detecting the difference between the voltage across the first resistor and the voltage across the second resistor; It is equipped with a comparator that compares the difference with a predetermined voltage and outputs the result as a result of detecting contact between subscriber lines.

Therefore, according to the present invention, it is possible to realize a subscriber circuit that can detect the occurrence of subscriber line crosstalk and notify the higher-level control device. By using this subscriber circuit, it is possible to quickly notify the higher-level control device of subscriber line interference, and the normal operation of the subscriber circuit can be prevented for a long time due to subscriber line interference. Ill be able to avoid being harmed. As a result, it will be possible to improve services for subscribers.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram showing an embodiment of a subscriber circuit of a telephone exchange according to the present invention.1...Subscriber terminal 2...A line 3 of subscriber line... ... B line 4 of subscriber line ... Switch circuit 5 ... Power supply circuit 6.7 ... Constant resistance 8.9 ... Transistor 10 ... Touch detection display circuit 11 ~14... Comparator

Claims (1)

[Claims] (1) A switch circuit that is connected to the subscriber terminal by the A line and B line of the two-wire subscriber line and switches the polarity of the voltage applied between the A line and the B line; 1
In the subscriber circuit of a telephone exchange, the subscriber circuit of a telephone exchange is equipped with a power supply circuit that supplies earth air through a first resistor and voltage through a second resistor, and monitors the loop condition between the A line and the B line. Voltage difference detection means for detecting the difference between the voltage across the resistor and the voltage across the second resistor, and comparing the difference between the two voltages detected by the voltage difference detection means with a predetermined voltage, A subscriber circuit comprising: a comparator that outputs a result as a result of detecting contact between subscriber lines.