JPS6365187B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a subscriber circuit testing method, and in particular to a subscriber circuit characteristic testing method that allows highly accurate testing using only digital elements, and reduces deterioration due to loss, noise, etc. .

The subscriber circuit in an electronic exchange has the function of converting voice analog signals into digital signals such as PCM and transmitting them to the highway, and converting received digital signals into voice signals and transmitting them to subscriber lines. It has a 2-wire terminal for input/output and a 4-wire terminal for input/output of encoded digital signals. Further, the subscriber circuit includes a test signal input/output terminal connected to the two-wire side of the subscriber circuit via a switch in order to perform tests such as performance tests and function tests.

FIG. 1 is a connection layout diagram for performing a conventional subscriber circuit characteristic test.

Tests of subscriber circuits include characteristic tests such as analog characteristics, and function tests to check whether digital operations are normal, etc., but here we will limit ourselves to the former. In FIG. 1, subscriber circuits 11, 12...1
The digital line 1 connected to the right side of the switch reaches a switch frame or the like via a highway inside the exchange, and the subscriber line 2 connected to the left side reaches a subscriber terminal outside the exchange. The subscriber circuits 11, 12...1n further include test signal input/output terminals 21A, 21B,
22A, 22B... _2oA , _2oB are provided, and switches 31A, 31B, 32A, 32B... _3oA ,
By closing 3 _o B, it is connected to the test signal line 17. The call current drawing circuit 6 is connected to the test signal line 1
Switches 31A, 31B, 32A, 32B...3 _o A, 3 _o that were once closed by passing a direct current through 7
Let B self-retain. Capacitors 7A and 7B are
It is used to send analog test signals and is connected to the subscriber circuit tester 8. Also,
The subscriber circuit tester 8 is connected to the digital signal line 1 via test lines 9 and 10, an insertion circuit 4, and a branch circuit 5.

Now, when performing a characteristic test of the subscriber circuit 11,
The subscriber circuit tester 8 receives the time/time allocated to the subscriber circuit 11 via the test line 9 in the insertion circuit 4.
Connect the test signal to digital signal line 1 using the slot.
A path that passes through the digital-to-analog converter in the subscriber circuit 11, outputs analog signals to the terminals 21A and 21B, and returns to the subscriber circuit tester 8 via the test line 17 and the capacitors 7A and 7B. , and subscriber circuit tester 8 to capacitor 7
An analog test signal is sent to the test line 17 via A and 7B, inputted to the subscriber circuit 11 from the test signal terminals 21A and 21B, passed through an analog-to-digital converter, outputted to the digital signal line 1, and sent to the branch circuit. At step 5, the signal of the time slot assigned to the subscriber circuit 11 is taken out and returned to the subscriber circuit tester 8 through the test line 10 for testing. Of course, in this case, the switches 31A and 31B of the subscriber circuit 11 are controlled by the control section.
is closed.

Generally, there are multiple devices equipped with subscriber circuits (hereinafter referred to as line concentrators), but for economical reasons, subscriber circuit testers are mounted on separate racks from this integrated device, and usually multiple One tester is assigned to each line concentrator. In this case, since the line concentrator and the subscriber circuit tester are far apart, the test signal may suffer loss or noise addition while the analog signal is being transmitted through the test line 17 in Figure 1. This has the disadvantage that the measurement accuracy deteriorates.

The purpose of the present invention is to eliminate such conventional drawbacks and to test subscriber circuits with high accuracy without causing loss or noise even if the distance of the test line between the tester and the subscriber circuit is long. The purpose of this invention is to provide a subscriber circuit testing method that can be used.

In order to achieve the above object, the subscriber circuit testing method of the present invention includes a test signal input/output changeover switch on the two-wire side consisting of the A line and the B line, and a test signal input/output terminal connected to the switch. and a plurality of subscriber circuits equipped with encoded signal input/output terminals connected to the highway on the 4-wire side, between the A-line side test signal input/output terminals of the subscriber circuit under test and any subscriber circuit. and the B line side test signal input/output terminals, and send a test signal from the subscriber circuit tester connected to the highway to the time slot connected to one of the above subscriber circuits. The test signal is measured by passing it through the test signal input/output terminal of one subscriber circuit and the test signal input/output terminal of the other subscriber circuit, and then extracting the test signal from the time slot to which the other subscriber circuit is connected. It is characterized by Also, connect the A line side test signal input/output terminal of the subscriber circuit under test to the B line side test signal input/output terminal of the predetermined standard subscriber circuit, and connect the latter A line side test signal input/output terminal. The output terminal and the test signal input/output terminal on the B line side of the former are connected, and a test signal is sent from the subscriber circuit tester connected to the highway to the time slot connected to one of the subscriber circuits. Pass the test signal through the test signal input/output terminal of one subscriber circuit and the test signal input/output terminal of the other subscriber circuit, and then take out the test signal from the time slot to which the other subscriber circuit is connected. It is characterized by performing measurements.

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

FIG. 2 is a connection layout diagram for testing the characteristics of a subscriber circuit according to an embodiment of the present invention.

Note that in FIG. 2, the same numbers as in FIG. 1 represent the same things.

n subscriber circuits 11 to 1n in one line concentrator
Assume that we now want to test the characteristics of the subscriber circuit 12 when the subscriber circuit 12 is implemented.

First, under the control of a control unit (not shown), the switches 32A and 32B of the subscriber circuit under test 12 are closed, and another subscriber circuit, for example 1
Switches 3 _o A and 3 _o B of n are also closed. The communication current drawing circuit 15 supplies DC current to the closed switches through the communication current drawing line 14 and the test line 3, thereby self-maintaining the operation of the switches 32A, 32B, 3 _o A, and 3 _o B. Note that 13 is a noise removal filter. In addition, the call current drawing circuit 15 is
The input impedance is kept high for the test signal in the voice band (300Hz to 3400Hz) of the subscriber circuit.

The path of the test signal in FIG. 2 is from the subscriber circuit tester 16, through the test line 9 and the digital signal line 1, to the subscriber circuit under test 12, to the switch 32A,
32B and test signal input/output terminals 22A, 22B
The analog signal _is output _to the _test line ₃ from The signal line 1 returns to the tester 16 via the test line 10. At this time, the insertion circuit 4 sends out the test signal using the time slot assigned to the subscriber circuit 12, and the branch circuit 5 takes out the test signal from the time slot assigned to the subscriber circuit 1n.

Also, it enters other subscriber circuits 1n from the tester 16 via the test line 9 and digital signal line 1, and is connected to switches 3 _o A, 3 _o B and test signal input/output terminals 2 _o
A, 2 _o B are output as analog signals to the test line 3, and after being converted from analog to digital through the input/output terminals 22A, 22B of the subscriber circuit under test 12 and switches 32A, 32B, the signals are output to the digital signal line 1. from the test line 10 to the tester 16
Tests can also be performed on the route back to . At this time, the insertion circuit 4 selects the time slot connected to the subscriber circuit 1n and inserts the test signal,
Branch circuit 5 selects a time slot connected to subscriber circuit 12 and extracts a test signal.

Note that the communication current of the subscriber circuits 12 and 1n reaches the communication current drawing circuit 15 through the test wires 3 and 14, but if the subscriber circuit and the communication current drawing circuit 15 are installed at separate locations, Current lead wire 1
To prevent the noise mixed in step 4 from entering test line 3,
A noise removal filter 13 is installed near the subscriber circuits 11 to 1n.

By the way, there are cases where the input level diagram and the output level diagram differ at the test signal input/output terminal, but for this, the test is performed as described above without any correction, and the measured value is Standards for determining pass/fail can be defined in consideration of differences in input and output levels and diagrams.

However, the above method is a simple method, and in order to accurately measure the characteristics of the subscriber circuit, it is necessary to correct the difference in the input and output level diagrams. In this case, in order to automatically test any subscriber circuit, it is sufficient to insert a level adjustment element into the specific subscriber circuit and always perform the test in pair with this specific subscriber circuit. .

FIG. 3 is a connection layout diagram for performing a characteristic test of a subscriber circuit showing another embodiment of the present invention.

In FIG. 3, the same numbers as in FIGS. 1 and 2 represent the same items. In this case, fix one subscriber circuit with excellent characteristics as a test subscriber circuit in advance, and test all other subscriber circuits in pairs with this test subscriber circuit. conduct.

Now, when the n-th subscriber circuit 1n is fixed as a test subscriber, connect the B line side test input/output terminal 2 _o B of the subscriber circuit 1n to the A line side test line of the test lines 3. At the same time, connect the A line side test input/output terminal 2 _o A of the subscriber circuit 1n to the B line side test line.
to test the characteristics of any other subscriber circuit.

The test route runs from the tester 16 through the test line 9, the insertion circuit 4, and the highway 1 in exactly the same manner as in the case of FIG. After passing through the input/output terminal, the signal returns from the highway 1 to the tester 16 via the branch circuit 5.

As is clear from the figure, the difference between FIG. 3 and FIG. 2 is that the current drawing circuit 15, the telephone current drawing line 1
4. Noise removal filter 13 is no longer necessary. That is, when the test signal input/output selector switch is closed, the DC current for maintaining this operation is connected to the test signal by forming a loop through the subscriber circuit under test and the power supply in the test subscriber circuit 1n. A switch holding current flows through line 3. Now, the number of subscriber circuits to be measured is 11, and each subscriber circuit 11
~1n A line side test input/output terminals 21A, 22
A, 2 _o Assuming that a battery is connected to A,
In Figure 3, battery-21A-3-2 _o B-earth,
and battery 2 _o A-3-21B-DC current flows in both paths, and switches 31A, 31B, 3
The operations of _o A and 3 _o B are self-maintained.

In each of the embodiments shown in FIGS. 2 and 3, the test interface between the subscriber circuit tester 16 and the subscriber circuits 11 to 1n is a digital signal, so the noise tolerance is high and there is no loss. Furthermore, since the return paths of the analog test signals in the subscriber circuits 11 to 1n can be limited to within the same rack, the measurement accuracy can be maintained at a good level. Further, even if the return route of the test signal is limited to within the same rack in this way, the test equipment can be shared by a plurality of line concentrators as in the past, so there is no problem of increased costs.

As explained above, according to the present invention, the test signal is looped back between two subscriber circuits and the interface with the tester is performed using only digital signals, so there is less deterioration due to loss, noise, etc. Since the equipment can be constructed with high accuracy of digital processing type using only digital elements, it is possible to test subscriber circuits with high accuracy.
Furthermore, since it is possible to test a plurality of concentrators with one test device without sacrificing measurement accuracy, there is also a great economic effect.

[Brief explanation of drawings]

FIG. 1 is a connection layout diagram for performing a characteristic test of a conventional subscriber circuit, FIG. 2 is a connection layout diagram for a characteristic test of a subscriber circuit showing an embodiment of the present invention, and FIG.
The figure is a connection layout diagram for characteristic testing of a subscriber circuit, showing an embodiment of the present invention (invention of claim 2). 1: Highway (digital signal line), 2: Subscriber line, 3: Test line, 4: Insertion circuit, 5: Branch circuit, 6, 15: Call current drawing circuit, 7A, 7B:
Capacitor, 8, 16: Subscriber circuit tester, 9,
10, 17: test line, 11-1n: subscriber circuit,
21A, 21B, 22A, 22B, 2 _o A, 2 _o
B: Test signal input/output terminal, 31A, 31B, 32
A, 32B, 3 _o A, 3 _o B: Switch, 13: Noise removal filter, 14: Current lead-in line.

Claims (1)

[Claims] 1. A test signal input/output switch on the 2-wire side consisting of the A line and the B line, a test signal input/output terminal connected to the switch, and a code connected to the highway on the 4-wire side. In a plurality of subscriber circuits each having a signal input/output terminal, between the A line side test signal input/output terminals of the first and second subscriber circuits, and between the B line side test signal input/output terminals, A test signal is sent from a subscriber circuit tester connected to the highway to a time slot connected to one of the subscriber circuits, and the test signal is transmitted to each test signal input of both subscriber circuits. A subscriber circuit testing method characterized in that after passing through an output terminal, a test signal is taken out from a time slot connected to the other subscriber circuit and measured. 2. A test signal input/output switch on the 2-wire side consisting of A and B wires, a test signal input/output terminal connected to the switch, and an encoded signal input/output terminal connected to the highway on the 4-wire side. In a plurality of subscriber circuits equipped with, connecting the A line side test signal input/output terminal of the subscriber circuit under test and the B line side test signal input/output terminal of a predetermined standard subscriber circuit, The former B line side test signal input/output terminal and the latter A line side test signal input/output terminal are connected, and a time signal is connected from the subscriber circuit tester connected to the highway to one of the above subscriber circuits. After sending out a slot test signal and passing the test signal through each test signal input/output terminal of both subscriber circuits,
A subscriber circuit testing method characterized in that a test signal is extracted from a time slot connected to the other subscriber circuit and measured.