JPH09292309A - Optical pulse tester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform the test of a plurality of optical transmission lines automatically, without the replacement work of optical fibers and to detect the presence or absence of the abnormality of the main body of a device. SOLUTION: The optical pulses from an optical pulse generator 24 are selectively outputted to optical fibers 1 and to a reference optical fiber 22 through an optical switch 21. The light returning from the optical fibers are received by an optical receiver 25. A measuring control part 30 sequentially changes the optical switch 21, correlates the output signal of the optical receiver during the period, wherein a specified time elapses from the generation of the optical pulse in the optical pulse generator 24 to connecting terminals 21a-21d of the optical switch 21 and stores the signal in a memory 31. An abnormality judging means 32 detects the fault of each optical fiber 1 from the received signal stored in the memory 31, in accordance with each optical fiber 1. A self- diagnosis means 33 performs the diagnosis of the device itself, based on the received light signal stored in the memory 31, in accordance with the reference optical fiber 22 connected to the optical switch 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pulse test apparatus for testing an optical transmission line by injecting an optical pulse into an optical fiber and receiving light returning from the optical fiber. The present invention relates to technology for enabling automatic testing of transmission lines and self-diagnosis.

[0002]

2. Description of the Related Art FIG. 5 shows a configuration of a conventional optical pulse test apparatus 10 for testing an optical transmission line formed of an optical fiber. This optical pulse test apparatus 10 includes an optical pulse generator 11 that outputs pulsed light and a light receiver 12
And guide the optical pulse output from the optical pulse generator 11 to the optical fiber 1 to be tested through the optical connector 13,
An optical coupler 14 for guiding light (backscattered light or Fresnel reflected light) returning from the optical fiber 1 to the optical connector 13 side is provided, and a predetermined time elapses from the timing at which the optical pulse is output. The optical transmission line is tested on the basis of the output signal of the photodetector 12 during the period.

[0003]

However, in the conventional optical pulse test apparatus as described above, when a plurality of optical transmission lines are tested at the same place, the optical fiber of one optical transmission line is attached to the connector 13. , And the test result is confirmed. If there is no problem, the complicated work of replacing the optical fiber and testing the next optical transmission line is required.

Further, when there is an abnormality on the apparatus main body side, such as a decrease in the output of the pulse generator or a decrease in the sensitivity of the light receiver, it cannot be distinguished from the abnormality on the optical transmission line side.
There was also the problem of making incorrect decisions.

The present invention solves this problem and enables automatic testing of a plurality of optical transmission lines without replacing optical fibers, and an optical pulse that allows the user to easily know whether or not there is an abnormality in the apparatus body. The purpose is to provide a testing device.

[0006]

In order to achieve the above object, an optical pulse test apparatus according to claim 1 of the present invention comprises a plurality of connection terminals for connecting an optical fiber to be tested and the plurality of connection terminals. An optical switch (21) having a switching terminal optically connected to one of the terminals, and an optical pulse generator (24) for inputting an optical pulse to the switching terminal of the optical switch.
And a light receiver (25) for receiving light returning to the switching terminal side from the optical fiber which is connected to the connection terminal of the optical switch and which receives the optical pulse from the optical pulse generator.
And a memory (3 for storing the output signal of the light receiver).
1) and an optical switch switching means (30) for connecting the switching terminals of the optical switch to a plurality of connection terminals in a predetermined order.
And a connection in which the output signal of the photodetector during a predetermined time after the optical pulse generator has generated the optical pulse is connected to the switching terminal of the optical switch by the optical switch switching means. And a light reception signal storage means (30) for storing in the memory in association with the terminal.

According to a second aspect of the present invention, there is provided an optical pulse test apparatus in which a plurality of connection terminals for connecting an optical fiber to be tested and a switch optically connected to any one of the plurality of connection terminals are connected. An optical switch (21) having a terminal, a reference optical fiber (22) having a predetermined length connected to one of a plurality of connection terminals of the optical switch, and an optical pulse for inputting an optical pulse to a switching terminal of the optical switch. A pulse generator (24) and a light receiver (25) for receiving the light returning to the switching terminal side from the optical fiber connected to the connection terminal of the optical switch and receiving the optical pulse from the optical pulse generator. ) And a memory (31) for storing the output signal of the light receiver
An optical switch switching means (30) for connecting the switching terminal of the optical switch to a plurality of connection terminals in a predetermined order,
The output signal of the photodetector from the generation of the optical pulse by the optical pulse generator until a predetermined time elapses is stored in the memory in association with the connection terminal connected to the switching terminal of the optical switch. Light reception signal storage means for storing (30)
And a self-diagnosis means (33) for diagnosing the apparatus itself based on the received light signal stored in the memory corresponding to the connection terminal to which the reference optical fiber is connected.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of an optical pulse test apparatus 20 of one embodiment. The optical pulse test apparatus 20 forms a monitoring system for an optical transmission line together with a center apparatus 40 connected via a telephone line, receives schedule information from the center apparatus 40, and receives a plurality of schedule information according to the schedule. The optical transmission line is automatically tested, the occurrence of disconnection accidents, deterioration, etc. are detected and sent to the center side.

The optical pulse test apparatus 20 has three connectors 20a for connecting the optical fiber 1 from the outside.
20b and 20c are provided. Each connector 20a-
20c is connected to the 1-to-4 optical switch 21.

The optical switch 21 has four connection terminals 21a.
To 21d and one switching terminal 21e, and the connection terminals 21a to 21d are received by a switching signal from a measurement control unit 30 described later.
One of the switches 21d is optically connected to the switching terminal 21e. This optical switch 21 is, for example, as shown in FIG. 2, a fiber movable in which the other end side of the optical fiber 21f whose one end side is connected to the switching terminal 21e is moved by the moving device 21g to be connected to each connection terminal 21a to 21d. It is of a type.

Three connection terminals 21a to 21a of the optical switch 21.
21c is fiber-connected to each of the connectors 20a to 20c, and one end side of a reference optical fiber 22 having a predetermined length (for example, 50 m) provided in the device with a known attenuation characteristic and the like is connected to the connection terminal 21d. ing.

The switching terminal 21e of the optical switch 21 has an optical pulse generator 24 and a light receiver 25 via an optical coupler 23.
It is connected to the.

The optical coupler 23 outputs the optical pulse output from the optical pulse generator 24 to the switching terminal 21e of the optical switch 21.
And the light returning from the switching terminal 21e to the optical coupler 23 is incident on the light receiver 25. The light receiver 25 outputs a light reception signal corresponding to the intensity of the received light to the A / D converter 26. The A / D converter 26 converts the received light signal output from the light receiver 25 into a digital signal and averages the averaging circuit 2
Output to 7.

The averaging circuit 27 is a series of received light signal data obtained each time when an optical pulse is output a predetermined number of times (eg 10 times) to one optical fiber connected to the optical switch 21. Are averaged a predetermined number of times, and the averaged result is output to the measurement control unit 30. That is,
A series of received light signal data output from the A / D converter 26 is stored in the internal memory in the order of addresses from the timing when the first optical pulse is output until a predetermined time elapses, and the second optical pulse is stored. The light-receiving signal data for is added to the previous light-receiving signal data stored in the internal memory and stored. Then, when this operation is performed a predetermined number of times, each data accumulated and stored in the internal memory is reduced to 1/10 and averaged, and the averaged received light signal data is used as the test result of the optical fiber, and the measurement control unit Output to 30.

The measurement control unit 30 has the optical switch switching means and the received light signal storage means of this embodiment, and according to the schedule information sent from the center device 40, the optical switch 21, the optical pulse generator 24 and the average. The averaging circuit 27 is controlled to periodically test the optical fiber connected to each connection terminal of the optical switch 21, and the received light signal data averaged by the averaging circuit 27 is associated with each connection terminal. It is stored in the memory 31.

The abnormality determining means 32 is the same as that of the optical switch 21.
Based on the received light signal data stored in the memory 31 in association with the one connection terminal 21a to 21c, each connector 20
It is determined whether or not there is a break in the transmission line of the optical fiber connected to a to 20c or a large deterioration.

For example, as shown in FIG. 3A, the far end position (address of the memory 31) P where the level of the received light signal is greatly reduced to the noise level is obtained, and that position is the far end at the time of the previous test. If it is deviated from the position P ', it is determined that a disconnection accident has occurred in the optical transmission line.

Further, as shown in FIG. 3B, the far end position P
When the degree of attenuation (gradient) of the received light signal is large in the non-positional range Qa to Qb, it is determined that the transmission path in that range is deteriorated. The changed portions Ra and Rb in FIG. 3 are due to reflection and attenuation occurring at the connection point of the optical fiber. When the abnormality determining means 32 determines that an abnormality has occurred in the transmission path, it sends information indicating the occurrence of the abnormality and the received light signal data to the communication control unit 34, which will be described later.

The self-diagnosis means 33 includes a reference optical fiber 22.
The optical pulse test apparatus 20 itself is diagnosed based on the received light signal data stored in the memory 31 in association with the connection terminal 21d of the optical switch 21 to which is connected.

For example, as shown in FIG. 4, the pulse width T of the Fresnel reflection generated at the far end position Pr of the received light signal data.
By determining whether or not the pulse width T is within a predetermined range, it is possible to diagnose whether the width of the optical pulse output from the optical pulse generator 24 has spread. Further, by determining whether or not the level L of the backscattered light at the far end position Pr is within a predetermined range, the output intensity of the optical pulse generator 24 and the sensitivity of the light receiver 25 are reduced, and the loss of the optical switch 21 is lost. Diagnose the increase. Further, the slope of the rising waveform and the falling waveform of the Fresnel reflection pulse at the far end position Pr is obtained, and it is determined whether or not this slope is within a predetermined range to determine whether or not the bandwidth of the photodetector 25 has changed. To diagnose. The changed portion Rc in FIG. 3 is the optical switch 2
This is due to the reflection and the attenuation generated at the portion 1 and the connector 20d.

When the self-diagnosis means 33 diagnoses that the device itself is abnormal, it sends the information indicating the abnormality of the device itself and the received light signal data to the communication control section 34.

The communication control unit 34 uses the judgment result of the abnormality judging means 32 and the diagnosis result of the self-diagnosis means 33 as the modem device 3.
5 to the center device 40, and the center device 4
The schedule information sent from 0 is measured and controlled by the measurement control unit 30.
Set to.

The center device 40 is connected to a plurality of optical pulse test devices 20 by a telephone line, receives information indicating an abnormality and received light signal data from the optical pulse test device 20, and detects the abnormality in the optical transmission line. Determine where it occurred,
Also, after confirming the occurrence of abnormalities in the optical pulse tester itself,
Instruct recovery processing.

As described above, this optical pulse test apparatus 20
Has an optical switch 21, means for switching the optical switch in a predetermined order, and means for storing the test results of the optical fibers connected to the optical switch.
It is possible to automatically test a plurality of optical transmission lines.
Also, connect the reference optical fiber provided in the device that is unlikely to cause disconnection or deterioration to one of the connection terminals of the optical switch,
Since the operating state of the device itself is diagnosed from the test result, the abnormality of the device itself is not erroneously determined as the abnormality of the optical transmission line.

[0025]

Other Embodiments The optical pulse test apparatus of the above embodiment is configured to receive information from the center apparatus side, test the optical transmission line, and send the test result to the center apparatus. The present invention can be similarly applied to an independently usable optical pulse test apparatus having an operation section for setting test conditions and the like and a display section for displaying test results. In this case, the test procedure is registered in advance from the operation unit so that the test is performed in the determined transmission line order and the test result is stored in the memory, and the test result (the pass / fail judgment result and the received light signal data) is stored. May be selectively read by the operation of the operation unit and displayed on the display.

In the case of such an optical pulse test apparatus that can be used alone, the optical switch 21 is turned on when the power is turned on.
Connect to the reference optical fiber side, the diagnosis of the device is performed with priority, the result is displayed on the display unit, or if there is an abnormality, if it is configured to generate an alarm sound, You can trust the results of the optical transmission tests performed on the.

Further, in the above embodiment, the one-to-four optical switch is used, but one-to-two, one-to-three or an optical switch having five or more connection terminals can be used. Also, regarding the structure of the optical switch, not only the above-mentioned movable optical fiber type, but also the angle of the reflecting mirror arranged at the intersection of the optical axes of the plurality of connection terminals and the switching terminals is changed, or the intersection of the reflecting mirrors is changed. A movable type of a reflecting mirror that moves back and forth may be used, or a waveguide type that switches an optical path by applying an electric field may be used.

Further, in the above-mentioned embodiment, the abnormality determination of the optical transmission line is automatically made from the received light signal of the light returning from the optical fiber. May be determined by the operator.

[0029]

As described above, the optical pulse test apparatus of the present invention has an optical switch connectable to an optical fiber, a means for switching the optical switch in a predetermined order, and a test result for the optical fiber connected to the optical switch. Means for storing in a memory in association with the terminals of the optical switch, it is possible to automatically test a plurality of optical transmission lines without replacing the connector. A system for monitoring can be realized.

Further, the apparatus itself is diagnosed based on the test result of the reference optical fiber of a predetermined length connected to one of the plurality of connection terminals of the optical switch. It is possible to immediately know whether the abnormality is on the optical transmission line side or the device side, and there is no fear of making an incorrect decision.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a diagram showing an example of a test result of an optical transmission line according to an embodiment.

FIG. 3 is a diagram showing an example of test results of a reference optical fiber according to an embodiment.

FIG. 4 is a diagram showing a configuration of a conventional device.

[Explanation of symbols]

 1 Optical Fiber 20 Optical Pulse Test Device 21 Optical Switch 22 Reference Optical Fiber 23 Optical Coupler 24 Optical Pulse Generator 25 Optical Receiver 27 Averaging Circuit 30 Measurement Control Unit 31 Memory 32 Abnormality Judgment Device 33 Self-Diagnosis Device 40 Center Device

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[Procedure amendment]

[Submission date] June 24, 1996

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] All figures

[Correction method] Change

[Correction contents]

[Fig. 2]

[Figure 3]

FIG. 4

[Figure 5]

FIG. ─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] July 11, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Brief description of drawings

[Correction method] Change

[Correction contents]

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a diagram showing a structure of a main part of one embodiment.

FIG. 3 is a diagram showing an example of a test result of an optical transmission line according to an embodiment.

FIG. 4 is a diagram showing an example of test results of a reference optical fiber according to an embodiment.

FIG. 5 is a diagram showing a configuration of a conventional device.

[Description of Reference Signs] 1 optical fiber 20 optical pulse test device 21 optical switch 22 reference optical fiber 23 optical coupler 24 optical pulse generator 25 light receiver 27 averaging circuit 30 measurement control unit 31 memory 32 abnormality determination unit 33 self-diagnosis unit 40 Center device

Claims (2)

[Claims] 1. An optical switch (21) having a plurality of connection terminals for connecting an optical fiber to be tested and a switching terminal optically connected to any one of the plurality of connection terminals.
An optical pulse generator (24) for inputting an optical pulse to a switching terminal of the optical switch; and an optical fiber connected to a connection terminal of the optical switch and receiving an optical pulse from the optical pulse generator, a switching terminal A light receiver (25) for receiving the light returning to the side, and a memory (31) for storing the output signal of the light receiver.
An optical switch switching means (30) for connecting a switching terminal of the optical switch to a plurality of connection terminals in a predetermined order, and a period from when the optical pulse generator generates an optical pulse until a predetermined time elapses. And a light reception signal storage means (30) for storing the output signal of the light receiver in the memory in association with the connection terminal connected to the switching terminal of the optical switch by the optical switch switching means. Test equipment. 2. An optical switch (21) having a plurality of connection terminals for connecting an optical fiber to be tested and a switching terminal optically connected to any one of the plurality of connection terminals.
A reference optical fiber (22) of a predetermined length connected to one of a plurality of connection terminals of the optical switch; an optical pulse generator (24) for inputting an optical pulse to a switching terminal of the optical switch; A light receiver (25) for receiving light returning from the optical fiber, which is connected to the connection terminal of the optical switch and which has received the optical pulse from the optical pulse generator, to the switching terminal side, and an output signal of the light receiver. Memory for storing (31)
An optical switch switching means (30) for connecting a switching terminal of the optical switch to a plurality of connection terminals in a predetermined order, and a period from when the optical pulse generator generates an optical pulse until a predetermined time elapses. Light receiving signal storage means (30) for storing the output signal of the light receiving device in the memory in association with the connection terminal connected to the switching terminal of the optical switch.
And a self-diagnosis means (33) for diagnosing the device itself based on the received light signal stored in the memory corresponding to the connection terminal to which the reference optical fiber is connected.