JPH0451617A - Loop back test control system for transmission path - Google Patents

Abstract

PURPOSE:To facilitate a loop back test by providing a loop back means which compares a signal on which a direct current from a reception transmission path is superimposed with a transmitted signal, records the number of the coincident times of the signal superimposes the direct signal on the signal received in a loop back device and loops back it to the reception transmission path in a preceding stage in a tester, and first and second transfer means. CONSTITUTION:A data transmission means 101 which superimposes the direct current on the signal transmitted to a transmission path and transmits it and a comparison means 108 which compares the signal on which the direct current from the reception transmission path is superimposed with the transmitted signal and records the number of coincident times are provided. The loop back means 205 which superimposes the direct current on the received signal and loops back it to the reception transmission path in the preceding stage when the direct current from the transmission path in the preceding stage is detected, the first transfer means 209 which superimposes the direct current on the received signal when the direct current is detected in the signal from the transmission path in the preceding stage and which transmits it to a transmission path in a subsequent stage, and the second transfer means 202 and 204 transmitting the signal which is received from the reception transmission path in the subsequent stage and to which the direct current superimposed to the reception transmission path in the subsequent stage are given to the loop back device. Thus, a loop back test can be conducted without the need of setting a test code.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a foldback test control method in a digital data transmission method using bipolar signals.

[Conventional technology]

In this type of loopback test control system, a different test code is defined for each device that performs loopback, and this test code is sent out from the tester to perform the loopback test.

For example, there is a subscriber system that connects two relay devices as shown in FIG. In other words, this subscriber system includes the tester 301
, an in-office device 302, relay devices 303 and 304, and an in-home device 305. In addition, the tester 301 and each device 30
1 to 305 are transmission transmission lines 306.308.310°3
12 and is connected by reception transmission lines 307.309.311.313.

In the case of such a subscriber system, the test code sent from the tester 301 is transmitted to the in-office device 302, the relay devices 303, 30
Four different test codes are defined for each of the devices 4 and 305, and the in-home device 305.

[Problem to be solved by the invention]

In the conventional loopback test control method described above, a test code is set for each device that performs loopback, so as the number of relay devices increases in the transmission path, a large number of different test codes must be set accordingly. There is.

Moreover, to give an example, in FIG.
In order to perform loopback tests on each of the relay devices 303 and 304 and the home device 305, four different test codes must be set, and these test codes are sent out sequentially when searching for a fault location. However, the disadvantage is that it requires time and effort.

Furthermore, when performing a loopback test when there is no fault, the signal on the transmitting transmission line is looped back to the receiving transmission line at the loopback target device, so the signal transmitted to this device through the receiving transmission line will not be transmitted any further. There are drawbacks.

The purpose of the present invention is to eliminate such drawbacks, and to provide a method that does not require multiple types of test cords and allows easy return testing.
The object of the present invention is to provide a loopback test control method for transmission lines.

[Means to solve the problem]

The present invention includes a tester that performs a foldback test on a transmission line in which data transmitted to a transmission line is looped back to a reception line, and a plurality of folding devices that sequentially loop back signals from the transmission line to the reception line. In a transmission line foldback test control method, the tester includes: a sending unit that superimposes a direct current on a signal to be transmitted to the transmitting transmission line, and sends out the superimposed direct current signal from the receiving transmission line, and the transmitted signal. and comparison means for recording the number of times the signals match, and when the folding device detects a direct current in the signal from the previous stage transmission transmission line, it superimposes the direct current on the received signal and returns the signal to the previous stage receiving signal. A folding means that loops back to the transmission line, and when detecting DC in the signal from the previous stage transmission transmission line, the first stage superimposes DC on the received signal and sends it to the next stage transmission transmission line.
and a second transfer means for transmitting the DC superimposed signal received from the next-stage reception transmission line to the previous-stage reception transmission line.

The present invention also provides a tester that performs a loopback test on a transmission line in which data transmitted to a transmission line is looped back to a reception line, and a tester that performs a loopback test on a transmission line in which data sent to a transmission line is looped back to a reception line, and a plurality of loopback tests for sequentially looping back signals from a transmission line to a reception line. In a transmission line foldback test control system comprising: a constant current source that superimposes a direct current onto the transmission transmission line; a switch circuit that controls the superposition of DC from the constant current source to the transmission transmission line; The loopback device includes a test circuit that controls the switch circuit, and a comparison circuit that compares the DC superimposed signal on the reception transmission path and the signal transmitted from the data transmission circuit and records the number of matches. A current detection circuit that detects direct current superimposed on a transmission transmission line, a constant current source that superimposes a direct current on the transmission transmission line, a switch circuit that controls the DC superposition from this constant current source to the transmission transmission line, and a transmission transmission. a data superimposition circuit that superimposes a DC signal from the channel onto the receiving transmission path and returns it; a timer circuit that controls these switch circuits and data superimposing circuits using the output signal of the current detection circuit; It is characterized by having a data transfer circuit that transfers the signal to the next stage device.

〔Example〕

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

1 and 2 are block diagrams showing one embodiment of the present invention. That is, in the transmission path loopback test control system, FIG. 1 is a block diagram showing an embodiment of the tester according to the present invention, and FIG. 2 is a block diagram showing an embodiment of the tester according to the present invention, and FIG. 1 is a block diagram showing an embodiment of a device that configures a transmission path and performs loopback; FIG. The tester shown in FIG. 1 is used as the tester 301 shown in FIG. 3, for example. In addition, the return device in FIG. 2 includes the in-office device 302 in FIG.
It is provided in relay devices 303 and 304 and in-home device 305.

The tester shown in FIG.
01, a constant current source 104 that superimposes a direct current onto the transmission transmission line, a switch circuit 105 that controls the superposition of DC from this constant current source 104 to the transmission transmission line, and this switch circuit 105.
a data receiving circuit 103 that receives data from the receiving transmission line via a receiving transformer 107, a signal superimposed on the receiving transmission line with DC, and a data receiving circuit 103 that receives data from the receiving transmission line, and receives data from the data transmitting circuit. and a comparison circuit 108 that compares the signals and records the number of matches.

The folding device in FIG. 2 also includes a transmitting transformer 206 provided between the transmitting transmission paths, a receiving transformer 207 provided between the receiving transmission paths, and a current detecting direct current superimposed on the transmitting transmission paths. A detection circuit 201, a constant current source 203 that superimposes DC onto the transmission transmission path, and a switch circuit 204 that controls the DC superimposition from this constant current source 203 to the transmission transmission path.
, a data superimposition circuit 205 that superimposes a DC signal from the transmission transmission path onto the reception transmission path and returns it, and a switch circuit 20
4 and the data superimposition circuit 205, the current detection circuit 201
The data transfer circuit 209 includes a timer circuit 202 that is controlled by an output signal from the receiver, and a data transfer circuit 209 that transfers a DC-superimposed signal to the reception transmission line to the next stage device via the arithmetic unit 208.

Next, the operation of this embodiment will be explained.

In the tester shown in FIG. 1, transmission data is transmitted from a data transmission circuit 101 through a transmission transformer 106 to a transmission transmission line outside the tester. Further, the received data passes through the receiving transformer 107 from the receiving transmission path and is received by the data receiving circuit 103.

In addition, in the tester shown in FIG. 1, when performing a loop test, the switch circuit 105 is operated under the control of the test circuit 102 to superimpose the DC current of the constant current source 104 on the transmission transmission path. The superimposed direct current serves as a signal to start the loopback test in the devices at the next and subsequent stages.

On the other hand, the comparison circuit 108 compares the data transmitted from the data transmission circuit 101 and the signal folded back by the device on this transmission path, which is DC-superimposed on the data received by the data reception circuit 103, and finds a match. Record the number of times.

This number indicates the number of devices on the transmission path from the tester to which the loop is correctly looped back.

In the loopback device shown in FIG. 2, when a loopback test is not performed, data from the tester that has passed through the transmission transmission path passes through the transmission transformer 206 and is sent to the next stage device. Data from the home device that has passed through the reception transmission path passes through the reception transformer 207 and is sent to the next device.

Furthermore, when performing a loopback test in the loopback device shown in FIG. 2, the DC current superimposed on the transmission transmission line by the previous device is detected by the current detection circuit 201, and the timer circuit 202 is activated.

This timer circuit 202 sends a signal for a certain period of time so that a data superimposition circuit 205 superimposes a DC signal from the transmission transmission path onto the reception transmission path and returns the signal. As mentioned above, the returned data is sent to the comparison circuit 108 of the tester shown in FIG.
The data is compared with the data sent from the tester, and the number of matches is recorded.

After a predetermined period of time has elapsed, the timer circuit 202 releases control over the data superimposition circuit 205 and stops looping back.

Next, the timer circuit 202 controls the switch circuit 204 to superimpose the DC current of the constant current source 203 onto the transmission transmission path. In this way, the same operation is caused in the next-stage device, and the loop test is performed continuously. Further, the signal that has been looped back and superimposed on the reception transmission line by the previous stage device is transferred by the data transfer circuit 209 to the next stage and subsequent devices, and detected by the comparison circuit 108 of the tester shown in FIG.

Such a tester and folding device are used in the system shown in FIG. 3, as described above. When a DC current is superimposed on the transmission transmission line 306 by the tester 301 as a starting signal for the loopback test, the in-office device 302 transfers the data from the transmission transmission line 306 to the reception transmission line 307 in the form of DC superposition.
Fold back to. The tester 301 uses this signal to confirm that the transmitted and received signals match, and records 1 as the number of matches. Next, after a certain period of time, the in-office device 302 ends the loopback and superimposes a DC signal on the transmission transmission line 308.

This signal is detected by the relay device 303 and transmitted through the transmission line 30.
The data from 8 is looped back to the receiving transmission line 309 in the form of DC superposition. The in-office device 302 directly superimposes the signal superimposed on the transmission transmission line 308 onto the transmission transmission line 307 with direct current. Similarly, the tester 301 increments the number of signal coincidences by 1 and records it as 2.

Thereafter, similar operations are performed by each device in the transmission path.

At that time, the number finally recorded in the tester 301 indicates how many devices on the transmission path have been successfully looped back, counting consecutively from the test record 301.

〔Effect of the invention〕

As explained above, the present invention can perform a loop test on each device connected to a transmission line without requiring the setting of test cords for the loop test, and the loop is performed in the form of DC superposition. Since it is transmitted, it has the effect that, for example, a bipolar signal from an in-home device transmitted through a reception transmission path can also be received by the tester.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of a tester according to the present invention. FIG. 2 is a block diagram showing an example of a loopback test device according to the present invention. FIG. 3 is an example of a transmission system during a loopback test. FIG. 101...Data transmission circuit 102...Test circuit 103...Data reception circuit 104...Constant current source 105...Switch circuit 106...Transmission Transformer 107...Reception transformer 108...Comparison circuit 201...Current detection circuit 202...Timer circuit 203...Constant current source 204...Switch Circuits, data superimposition circuits, transmitting transformers, receiving transformers, arithmetic units, data transfer circuits

Claims (2)

[Claims] (1) A tester that performs a loopback test on a transmission line in which data sent to the transmission line is looped back to the reception line, and multiple folding devices that sequentially loop back signals from the transmission line to the reception line. In the loopback test control method for a transmission line, the tester includes a sending means for superimposing a direct current on a signal to be transmitted to the transmitting transmission line, and a signal superimposed with a direct current from the receiving transmission line, and a transmitted signal. and a comparison means for recording the number of times the signals match, and when the folding device detects direct current in the signal from the previous stage transmission transmission line, it superimposes the direct current on the received signal and transmits the received signal in the previous stage. When a direct current is detected in the signal from the previous stage transmission transmission line, the first stage superimposes the DC on the received signal and sends it to the next stage transmission transmission line.
and a second transfer means for transmitting a DC superimposed signal received from a next-stage receiving transmission line to a previous-stage receiving transmission line. (2) A tester that performs a loopback test on a transmission line in which data sent to the transmission line is looped back to the reception line, and multiple folding devices that sequentially loop back signals from the transmission line to the reception line. In the transmission line foldback test control method, the tester includes: a constant current source that superimposes a direct current onto the transmission transmission line; a switch circuit that controls the DC superposition from this constant current source to the transmission transmission line; It has a test circuit for controlling, a comparison circuit that compares the DC superimposed signal on the receiving transmission line and the signal transmitted from the data transmitting circuit, and records the number of matches, and the folding device is connected to the sending transmission line. a current detection circuit that detects direct current superimposed on the transmitting transmission line; a constant current source that superimposes the direct current on the transmitting transmission line; a switch circuit that controls the direct current superimposing from this constant current source onto the transmitting transmission line; A data superimposition circuit that superimposes a DC signal onto the receiving transmission path and returns it; a timer circuit that controls these switch circuits and data superimposing circuits using the output signal of the current detection circuit; 1. A transmission path loopback test control method comprising a data transfer circuit for transferring data to a next-stage device.