JPS61218257A - Test system for subscriber circuit - Google Patents

Abstract

PURPOSE:To check various functions provided with a subscriber circuit by providing a lead contact for subscriber line test, a contact for sending a call signal, a current detecting circuit and a loop forming means. CONSTITUTION:Contacts 15 and 16 are provided as lead-in contacts for subscriber line test to both talking lines at two-wire side in a subscriber circuit 1 and a contact 19 for call signal sending is provided between the contact 15 and a feeding circuit 9. Further, a supervisory circuit 12b as a current detection circuit switching the detecting sensitivity of a current flowing to a line (b) is provided to the feeding circuit 9. Further, a relay 24, a resistor 23 and a contact 25 as a loop forming means for forming a loop circuit having the permissible maximum resistance value of a subscriber line resistor, and a termination circuit 22 are provided between the midpoint of the contacts 15, 19 and the contact 16, the feeding circuit 9. A prescribed control signal S1 is sent sequentially from a controller in a prescribed procedure to detect supervisory signals S2 and S3, a test signal is inputted from a test device 29 to measure the test signal returned from the subscriber circuit 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to improvements in subscriber circuit testing methods in digital exchanges.

In a digital exchange, subscriber circuits are equipped with functions such as power supply, calling signal transmission, subscriber loop monitoring, two-wire and four-wire conversion, and code decoding.

Therefore, it is desirable to economically realize means that can test any subscriber circuit in order to always confirm that the various functions described above are normal.

[Conventional technology]

FIG. 2 is a diagram showing an example of a conventional subscriber circuit testing method for this type of subscriber circuit.

In FIG. 2, the subscriber circuit l is provided with relays 2 and 3.

When testing the above-mentioned functions of the subscriber circuit 1, a control device (not shown) transmits a control signal S1 for operating the relay 3 to the register 4 in the subscriber circuit 1. As a result, relay 3 is activated and contacts 5 and 6 reconnect the a and b wires from terminals A and B to test terminals 7 and 8.

The test terminals 7 and 8 are connected to a subscriber circuit test device (not shown) that is provided in common to the plurality of subscriber circuits 1. The subscriber circuit testing device performs various functions provided in the subscriber circuit 1, namely, a power supply function by a power supply circuit 9, and a relay 10.
Ring trip circuit 1
1, the subscriber loop monitoring function by the monitoring circuits 12a and 12b, the code decoding function and the two-line/four-wire conversion function by the code decoding circuit 13 and the two-line/four-wire conversion circuit 14, etc. are tested.

Note that when a control signal S1 for operating the relay 2 is transmitted to the register 4 from a control device (not shown), the relay 2 is operated and the subscriber line connected to the terminals A and B is connected to the contact 1.
5 and 16 are connected to test terminals 17 and 18. The test terminals 17 and 18 are connected to a subscriber line test device (not shown) that is provided in common to the plurality of subscriber circuits 1, and is used to measure the line resistance, insulation resistance, line capacitance, etc. of the subscriber lines. Tests can be conducted on the passenger track side.

[Problem to be Solved by the Invention 3] As is clear from the above explanation, in the conventional subscriber circuit testing system, a relay 3 is provided in each subscriber circuit 1, and a relay 3 is provided in each subscriber circuit 1, and Various functions of the subscriber circuit 1 were tested by connecting it to the subscriber circuit test equipment provided.

Therefore, it is necessary to provide a relay 3 and test terminals 7 and 8 in each subscriber circuit 1, which may impede miniaturization and high-density packaging of the subscriber circuit 1. It is necessary to provide circuit testing equipment. Furthermore, among a plurality of subscriber circuits that share a subscriber circuit testing device, only one circuit can be tested at a time, which may increase the time required for testing.

[Means for solving problems]

The present invention solves the above problems by providing the following means.

That is, in the present invention, lead-in contacts for subscriber line testing are provided on both communication lines on the second line side, as in the conventional case.

Next, a contact for sending a calling signal is provided between the lead-in contact provided on one of the communication lines and the power supply circuit connected to the other communication line.

Further, a current detection circuit capable of switching the detection sensitivity of the current flowing through the other communication line is provided in the power supply circuit.

In addition, a termination consisting of a series circuit of a resistor and a capacitor is installed between the lead-in contact on one communication line and the call signal sending contact, and between the lead-in contact on the other communication line and the other power supply circuit. A loop forming means is provided for forming a loop circuit having a resistance value of the maximum allowable value of the subscriber line resistance.

In such a subscriber circuit, the lead-in contact is first opened.

Next, when the calling signal sending contact is operated and the current detection sensitivity of the current detection circuit is switched, the calling signal sent from the calling signal sending contact to the A line flows to the power supply circuit via the termination circuit, and the current The calling signal sending function is tested by being detected by the detection circuit.

When a loop circuit is formed by the loop forming means in the calling signal sending state, the ring trip circuit incorporated in the calling signal sending path operates, and at the same time when the output from the above calling signal sending detection circuit disappears, the A line The normality of the ring trip function is confirmed by confirming that the current detection circuit on the side operates. Further, a current detection circuit provided in the power supply circuit detects the direct current flowing through the loop forming means, thereby testing the power supply function and the loop monitoring function.

Connect the loop circuit to the test equipment via the communication line network, input the test signal from the test equipment to the 4-wire receiving terminal via the communication line network, and establish the balanced connection of the two-wire/four-wire conversion circuit. 4 due to the impedance mismatch between the network and the loop circuit.
The test signal sent back to the line transmission terminal is received by the test device via the communication channel network and measured within the test device, thereby testing the two-line and four-wire conversion function and code decoding function.

[Effect]

That is, according to the present invention, the pull-in contact, the call signal sending contact, and the loop forming means are sequentially operated according to a predetermined procedure, and a simple test device that only transmits and receives test signals is connected to the subscriber via the communication network. By connecting to the circuit, various functions of the subscriber circuit can be tested, and there is no need to install complicated and expensive subscriber circuit testing equipment. It also eliminates the need for connection lines with the network, and allows any subscriber circuit to be tested in parallel.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a subscriber circuit testing method according to an embodiment of the present invention. Note that the same reference numerals indicate the same objects throughout the figures.

In FIG. 1, in the subscriber circuit 1, contacts 15 and 16 are provided as lead-in contacts for subscriber line testing on both communication lines (a line and b&lI) on the two-line side as in the conventional manner.

Next, a contact 19 for sending a calling signal is provided between the contact 15 provided at avA and the power supply circuit 9 connected to a'm.

Further, a monitoring circuit 12b is provided in the power supply circuit 9 as a current detection circuit capable of switching the detection sensitivity of the current flowing in the b line.

Also, between the contacts 15 and 19 provided on the a line, and the b
A termination circuit 22 is provided between the contact point 16 provided on the line and the middle of the power supply circuit 9 and is constituted by a series circuit of a resistor 20 having a resistance value of 600 ohms and a capacitor 21 having a capacitance of 1 microfarad. , a resistance value of 12 ohms is used as a loop forming means for forming a loop circuit having a resistance value of the maximum permissible value of subscriber line resistance (for example, 1800 ohms).
A resistor 23 with 00 ohms, a relay 24 and contacts 25 are provided.

In such a state, the control device (not shown) sends a control signal S to operate the relay 2 to the subscriber circuit 1 to be tested.
1 to register 4. As a result, relay 2 operates and contacts 15 and 16 disconnect the a and b wires from terminals A and B.

Next, a control device (not shown) transmits to the register 4 a control signal S1 that operates the relay 10 and increases the current detection sensitivity of the monitoring circuit 12b that detects the current flowing in the b line. As a result, the relay 10 operates, and the calling signal supplied from the calling signal terminal 26 is sent to the a line via the ring trip circuit 11 and the 19 contacts in the operating state, and is sent to the a line via the termination circuit 22 and the b line. The current flows to the power supply circuit 9.

Furthermore, the current detection sensitivity of the monitoring circuit 12b is improved compared to normal. As a result, the monitoring circuit 12b detects the calling signal flowing through the power supply circuit 9, and sends the detection result back to a control device (not shown) as a monitoring signal S2.

The control device that receives the supervisory signal S2 confirms that the calling signal sending function of the subscriber circuit 1 is normal.

Next, a control device (not shown) transmits a control signal S1 for operating the relay 24 to the register 4 of the subscriber circuit 1 which is in the calling signal sending state. As a result, the relay 24 operates,
A resistor 23 is connected in parallel to the capacitor 21 of the termination circuit 22 through a contact 25 .

As a result, a loop circuit 27 having a resistance value of 1800 ohms is formed between the a line and the b line, and is made up of a series circuit of resistors 20 and 23.
DC current supplied from the loop circuit 27 flows through the loop circuit 27.

When the ring trip circuit 11 detects the DC current and performs a known ring trip operation, the relay 10 is restored and the sending of the ringing signal is stopped, and the loop circuit 27 is connected to the power supply circuit 9.
DC current is supplied from the

When the monitoring circuit 12a detects the direct current flowing through the a-line, it transmits the detection result to a control device (not shown) as a monitoring signal S3. The control device that receives the supervisory signal S3 confirms that the ring trip function, power supply function, and subscriber loop monitoring function of the subscriber circuit 1 are normal.

In such a state, the two-wire side of the two-wire/four-wire conversion circuit 14 is terminated by the loop circuit 27 with a resistance value of 1800 ohms, and
There is an impedance mismatch with a balanced wiring network having an impedance value of ohms.

In this state, a control device (not shown) connects the test device 29 to the subscriber circuit l via the communication path network 28, and
When a test signal is input from 9 to the 4-wire receiving terminal of the subscriber circuit 1, the test signal is converted from digital format to analog format by the code/decoding circuit 13, and sent to the 4-wire receiving terminal of the 2-wire/4-wire conversion circuit 14. communicated. Since the two-wire/four-wire conversion circuit is in an impedance mismatched state as described above, the analog format test signal is 4V depending on the degree of impedance mismatch.
The signal is transmitted to the transmission side, converted from analog format to digital format by the code/decoding circuit 13, and sent back to the test device 29 from the 4-wire transmission terminal via the communication channel network 28.

The test device 29 measures the test signal level returned from the subscriber circuit 1, compares it with the test signal reception level calculated in advance from the impedance mismatch degree, and detects that it is within a predetermined deviation value. As a result, it is determined that the two-wire/four-wire conversion function and code decoding function of the subscriber circuit 1 are normal.

As is clear from the above description, according to the present embodiment, the subscriber circuit 1 is equipped with It is possible to test the ringing signal sending function, ring trip function, power supply function, and subscriber loop monitoring function, and also inputs a test signal from the test value 229 via the communication path network 28 and returns the test signal from the subscriber circuit 1. By measuring , it becomes possible to test the two-line and four-line conversion function and code decoding function.

(Effects of the Invention) As described above, according to the present invention, in the subscriber circuit, the retracting contact, the calling signal sending contact, and the loop forming means are sequentially operated according to a predetermined procedure, and only the test signal is transmitted and received. By connecting a simple test device to the subscriber circuit via the communication path network, various functions of the subscriber circuit can be tested, eliminating the need for complicated and expensive subscriber circuit test equipment, and making it possible to Test terminals for subscriber circuits and connection lines between test terminals and subscriber circuit testing equipment are also eliminated, and arbitrary subscriber circuits can be tested in parallel.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a subscriber circuit testing method according to an embodiment of the present invention, and FIG. 2 is a diagram showing an example of a conventional subscriber circuit testing method. In the figure, 1 is the subscriber circuit, 2.3.10 and 24
is a relay, 4 is a register, 5.6.15.16.19 and 25 are contacts, 7.8.17 and 18 are test terminals,
9 is a power supply circuit, 11 is a ring trip circuit, 12a and 12b are monitoring circuits, 13 is a code/decoder circuit, 14 is a two-wire/four-wire conversion circuit, 20 and 23 are resistors, 21 is a capacitor, 22 is a termination circuit, 26 is a A calling signal terminal, 27 a loop circuit, 28 a communication path network, and 29 a test device are shown. When I G 2

Claims (4)

[Claims] (1) In the subscriber circuit of a digital exchange, a lead-in contact for subscriber line testing is provided on both communication lines on the two-line side, and a power supply circuit is connected to the lead-in contact of one of the communication lines and the one communication line. and a current detection circuit capable of switching the detection sensitivity of the current flowing through the other communication line is provided in the power supply circuit, and a lead-in contact on the one communication line and the call signal emission contact are provided in the power supply circuit. and between the lead-in contact on the other communication line and the power supply circuit, a termination circuit consisting of a series circuit of a resistor and a capacitor, and a resistance value of the maximum permissible subscriber line resistance. and loop forming means for forming a loop circuit having the subscriber circuit, and each function of the subscriber circuit is tested by operating the pull-in setting, the calling signal sending contact, and the loop forming means in a predetermined procedure. Subscriber circuit test method. (2) After setting the lead-in contact to an open state, operate the call signal sending contact and switch the current detection sensitivity of the current detection circuit, so that the call signal flowing to the power supply circuit via the termination circuit is 2. The subscriber circuit testing method according to claim 1, wherein the calling signal sending function is tested by detection by a detection circuit. (3) A loop circuit is formed by the loop forming means in a calling signal sending state, and a current flowing through the loop circuit is detected by a current detecting circuit, and a current flowing through the one communication line provided in the power feeding circuit is ringed. A subscriber circuit testing method according to claim 1, characterized in that a trip function, a power supply function, and a loop monitoring function are tested. (4) A test signal is input to the 4-wire receiving terminal with the loop circuit formed, and is returned to the 4-wire transmitting terminal due to impedance mismatch between the balanced wire network of the two-wire and four-wire conversion circuit and the loop circuit. 2. The subscriber circuit testing method according to claim 1, wherein a two-line/four-wire conversion function and a code decoding function are tested by measuring a test signal.