JPH05199192A - Method and device for fault bracketing for light transfer system - Google Patents

Abstract

PURPOSE:To make a complete fault bracketing taking a point LI as a decomposition point by speedily performing the test of an intra-office transfer device and the test of a light transmission line. CONSTITUTION:The light signal sent from a light source section 1b on an intra- office transfer device 1 is branched through a light branching device 9a on an optical fiber 3. The branched light signal is folded by a light folding switch 10 and inserted into an optical fiber 7 through a light branching device 9b, performing the folding test at a circuit level. The pulse light from the light pulse test device 11 is inserted into the optical fiber 3. The pulse light is reflected as the pulse light reflection by an optical filter-type bracketing device 6a located near the remote transfer device 4. The location or amount of the pulse light reflection is compared with that which is measured when the optical fiber is normal so as to discriminate the presence or absence of the fault of the light transmission line. Further, the fault bracketing of the light transfer system is performed based on the result of the folding test at a circuit level and the result of the test of the light transmission line.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention, in an optical transmission system, automatically tests an internal transmission device and an optical transmission line, and easily detects whether telecommunication equipment or user equipment is out of order. However, the present invention relates to a fault isolation method and device capable of detecting a fault section in detail.

[0002]

2. Description of the Related Art As a method for performing fault isolation between an optical transmission line and an out-of-office transmission device by using an optical pulse tester, an optical coupler / divider, and an optical filter type discriminator, there is a conventional Japanese Patent Application No.
No. 232734 is provided.

FIG. 9 is a diagram for explaining the method described in Japanese Patent Application No. 2-232734, in which reference numeral 1 is a station inside transmission apparatus, 1a is an electric circuit section of the station inside transmission apparatus, and 1b.
Is a light emitting element, an electric circuit for converting an electric signal into an optical signal, and a light source section of an internal transmission device comprising an optical fiber and a light emitting element coupling section, 1c is a light receiving element, an electric circuit for converting an optical signal into an electric signal and an optical fiber And a light receiving element of the transmission device inside the station, which is composed of
Reference numeral 3 is an optical fiber outside the transmitting station.

In the figure, 4 is an outside transmission device, 4a is an electric circuit part of the outside transmission device, 4b is a light emitting element, an electric circuit for converting an electric signal into an optical signal, and an optical fiber and a light emitting element coupling part. The light source unit of the outside transmission device, 4c is a light receiving element, the electric circuit for converting an optical signal into an electric signal, and the light receiving unit of the outside transmission device including an optical fiber and a light receiving element coupling unit, 5 is a terminal device, and 6a is An optical filter type cut-off device that blocks the light pulse and reflects the light pulse in the opposite direction to the traveling direction, and 6b is an optical filter that transmits the communication light, blocks the test light, and does not reflect the light pulse. is there.

In the figure, 7 is an optical fiber outside the receiving side station, 8 is an optical fiber inside the receiving side station, 9a is an optical multiplexer / demultiplexer for the transmission side line, 9b is an optical multiplexer / demultiplexer for the reception side line, and 10 is an optical switch. 10A is the head part A of the optical switch,
Reference numerals 10a, 10b, 10c and 10d denote the optical multiplexer / demultiplexer 9
(9a, 9b) is an optical connector of an end portion of an optical fiber branched from (9a, 9b) and is housed in the optical switch 10. Code 1
1 is an optical pulse test device, 12 is a CPU (central processing unit), 13 is a database, 14 is an LI point (telecommunication equipment / user equipment demarcation point), and 24a, 24b, 24c and 24d are optical multiplexer / demultiplexers 9 (9a, 9b) and the optical switch 10 between the optical fibers.

The optical pulse test apparatus 11 inserts an optical pulse having a wavelength different from that of the communication light into the transmitting side out-of-station optical fiber 3 or the receiving side out-of-station optical fiber 7 via the optical switch 10 and the optical multiplexer / demultiplexers 9a and 9b. , The amount and position of the reflected light pulse of the optical filter type splitter 6a is detected, and the detected optical level and position are measured in advance for the transmitting side out-of-station optical fiber or the receiving side out-of-station optical fiber in a normal state. The optical level or position of the reflected light pulse that has been read is read from the database 13 to the CPU 12, and as a result of comparison, if there is a change in the optical level or position, it is determined that the optical fiber has a failure, and there is a failure. The position is determined, and if there is no fluctuation, it is determined that there is no failure in the optical fiber, so that failure isolation between the optical transmission line and the outside-site transmission device is performed.

On the other hand, a line level loopback test is provided as a method for testing the inside-office transmission apparatus 1 and the outside-office transmission apparatus 4, and FIG. 10 is a diagram for explaining this method. In this figure, parts corresponding to respective parts of the conventional optical transmission line and the fault isolation (FIG. 9) of the outside transmission device are designated by the same reference numerals, and the description thereof will be omitted. In FIG. 10, reference numeral 18 is a digital exchange,
19 is a loop 1 turning point, 20 is a transmitting side optical fiber,
Reference numeral 21 is a receiving side optical fiber, 22 is a loop 1, and 23 is a loop 2. Loop 1 (22) is a loopback test of the office internal transmission device 1. However, under the present circumstances, it is difficult to perform a loopback test at the light level including the light source section 1b and the light receiving section 1c, so that the loopback test is performed in the electric circuit section 1a. Loop 2 (23) is a loopback test at T point 15.

Next, a conventional optical pulse test apparatus 1
1. A method for performing fault isolation between the optical transmission line and the out-of-office transmission device 4 using the optical multiplexer / demultiplexers 9a and 9b and the optical filter type divisor, a pulse test device 11, a line level loopback test and an alarm. A flow in the case of performing fault isolation by providing transfer will be described with reference to FIG.

When it is detected that an abnormality has occurred in the optical transmission system by an alarm from the intra-station transmission device 1 or a notification from the communication service user (step SA1),
The inspector performs a loop 2 (23) test on the faulty line (step SA2), and determines whether or not the test result is normal (step SA3). In the judgment, "Y
When the result of "ES" is obtained, it is determined that the equipment from the digital exchange 18 to the user / network decomposition point (point T) is normal, that is, the terminal device 5 or the point T 15 has failed (step SA4).

In the judgment at step SA3, "N
When the result of "O" is obtained, that is, when it is determined that there is an abnormality in the equipment from the digital exchange 18 to the user / network decomposition point (point T), the process proceeds to step SA5 and loops for the failed line. 1 (22) is performed, and it is determined whether or not the test result is normal (step SA
6). In the judgment, when the result of "NO" is obtained, the digital exchange 18 from the loop 1 turning point 19 is obtained.
The side determines that there is a failure (step SA7). On the other hand, when the result of the determination in step SA6 is "YES", the equipment from the digital exchange 18 to the loop 1 (22) turning point 19 is normal, that is, the loop 1 turning point 19 to the T point 15 fails. And step SA
Go to 8. In step SA8, the pulse test apparatus 11 tests the optical fiber 3 on the transmitting side. next,
In step SA9, as a result of the above test, it is determined whether or not the optical fiber 3 outside the transmitting station is defective. When a “YES” result is obtained in step SA9,
It is determined that the optical fiber 3 outside the transmitting station is out of order (step SA10).

On the other hand, in step SA9, "N
When the result of “O” is obtained, the inspector determines that the pulse tester 1
1, the test of the receiving side outside station optical fiber 7 is performed (step SA11). Next, in step SA12, as a result of the above test, it is determined whether or not the receiving side external optical fiber 7 is defective. In step SA12,
When the result of "YES" is obtained, it is determined that the receiving side outside station optical fiber 7 has failed (step SA13). On the other hand, when the result of "NO" is obtained in step SA12, the optical multiplexer / demultiplexer 9 is switched from the loop 1 turning point 19 to
It is determined that either of the section (1) or the outside station transmission device 4 has a failure (step SA14).

[0012]

By the way, according to the method using the above-mentioned conventional technique, the cause of the failure is loop 1
If it is on the side of the exchange from the turnaround point 19, on the optical fiber section outside the office, or on the terminal equipment, it is possible to perform fault isolation. However, in the above-mentioned conventional technique, failure isolation cannot be performed when there is a failure in the section from the loop 1 turning point 19 to the optical multiplexer / demultiplexer 9 or in the outside office transmission device 4.

Here, in the optical transmission system, Table 1 shows the areas in which the fault can be separated according to the prior art and the present invention.

[Table 1] As shown in Table 1, in the conventional technique, in the optical transmission system system, the light source unit 1b and the transmission side intra-station optical fiber 2 of the intra-station transmission device, the light receiving unit 1c of the intra-transmission transmission device, and the reception-side intra-station optical device are included. If one of the three parts of the fiber 8 and the outside transmission device 4, that is, the section from the loop 1 turning point 19 to the optical coupler 9 and the two outside transmission device 4 fails, the failure occurs. Is it the telecommunications equipment side,
There was a problem in that automatic failure isolation could not be performed for the outside station transmission device 4 (user equipment side), and the operator had to rely on manpower.

The present invention has been made in view of the above-mentioned circumstances, and an optical system capable of rapidly performing a test of an internal transmission device and an optical transmission line and performing 100% fault isolation with a LI point as a demarcation point. It is an object of the present invention to provide a fault isolation method for a transmission system and a device therefor.

[0015]

In order to solve the above-mentioned problems, according to the invention of claim 1, the station of the optical transmission system comprising an internal transmission apparatus, an optical transmission line and an external transmission apparatus. In a fault isolation method for an optical transmission system in which a failure test of an outer transmission device and the optical transmission line is performed by an optical pulse test device, an optical signal transmitted from a light source unit provided in the internal transmission device is used as the optical signal. The optical signal is branched via an optical multiplexer / demultiplexer on the transmission path, the branched optical signal is folded back by an optical folding switch, and further inserted into the optical transmission path via the optical multiplexer / demultiplexer to perform a line-level folding test, The pulsed light from the optical pulse test device is passed through an optical multiplexer / demultiplexer to determine the level of pulsed light reflection by an optical filter type splitter placed in the vicinity of the outside transmission device of the optical transmission line. Or, by comparing the amount with the position or the amount of the optical transmission line measured when the optical transmission line is normal, the presence or absence of a failure of the optical transmission line is determined, and the result of the line-level loopback test and the failure determination of the optical transmission line are determined. It is characterized in that fault isolation is performed based on the result of.

According to a second aspect of the present invention, an optical pulse test device is used for a failure test of the outside transmission device and the outside transmission device of an optical transmission system including an inside transmission device, an optical transmission line and an outside transmission device. In a fault isolation test device for an optical transmission system performed by the method of performing a line level loopback test, an optical signal transmitted on the optical transmission line from the light source unit of the internal transmission device is pulled in, and the pulled-in optical signal is transmitted. While folding the signal and inserting it into the optical transmission line,
In the failure test of the optical transmission line, the pulsed light from the optical pulse test device is inserted into the optical transmission line, and the reflected light of the optical pulse reflected by the dividing means provided in the optical transmission line. And an optical return switch means for supplying the determination means to the determination means, and a fault isolation means for performing fault isolation based on a result of a line-level return test and a result of a failure test of the optical transmission line. To do.

According to a third aspect of the present invention, in the fault isolation device for an optical transmission system according to the second aspect, it is installed on the optical transmission line outside the receiving side station, and the outside transmission is performed during the loopback test. An optical switch for blocking the optical signal from the light source unit of the device is provided.

According to a fourth aspect of the present invention, in the fault isolation device for an optical transmission system according to the second aspect, the optical return switch means has an optical coupling / dividing device and an optical switch passing light loss at its return portion. In order to compensate for the above, an amplifying means for amplifying the optical signal is provided.

According to a fifth aspect of the present invention, in the fault isolation device for an optical transmission system according to the second aspect, the optical return switch means has a light emitting portion of a light source portion of the outside station transmission device at its return portion. In order to compensate the level gap between the level and the light receiving level of the light receiving section, an attenuating means for attenuating the optical signal is provided.

[0020]

According to the inventions of claims 1 and 2,
At the time of a line level loopback test, the optical signal transmitted from the light source unit provided in the internal transmission device is branched by the optical loopback switch means via the optical multiplexer / demultiplexer on the optical transmission line, and The branched optical signal is folded back, and is further inserted into the optical transmission line through an optical multiplexer / demultiplexer to perform a folding test. Further, in the failure test of the optical transmission line, the pulsed light from the optical pulse testing device is inserted into the optical transmission line by the optical return switch means via the optical coupler / splitter. The pulsed light is reflected by the optical filter type splitter arranged near the outside transmission device. Whether or not there is a failure in the optical transmission line is determined by comparing the position or amount of pulsed light reflection with the position or amount of the optical transmission line measured during normal operation. Then, based on the result of the line level loopback test and the result of the failure determination of the optical transmission line, failure isolation is performed by the failure isolation means.

According to the third aspect of the present invention, in the fault isolation device for the optical transmission system according to the second aspect, at the time of the loopback test, an optical switch installed on the optical transmission line outside the receiving side is used for the outside of the station. The light signal from the light source unit of the transmission device is blocked.

According to a fourth aspect of the present invention, in the fault isolation device of the optical transmission system according to the second aspect, the amplifying means provided at the folding portion of the optical folding switch means causes the optical multiplexer / demultiplexer and the optical switch to operate. The optical signal is amplified to compensate for the passing light loss.

According to the fifth aspect of the present invention, in the fault isolation device for an optical transmission system according to the second aspect, the light source section of the outside transmission apparatus is provided by the attenuating means provided at the turn-back section of the optical turn-back switch means. The optical signal is attenuated in order to compensate for the level gap between the light emission level of the light receiving unit and the light receiving level of the light receiving unit.

[0024]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. (First Embodiment) FIG. 1 is a diagram for explaining the first embodiment of the present invention. In FIG. 1, the parts of the fault isolation (FIG. 9) of the conventional optical transmission line and the outside office transmission device are shown. Corresponding parts are designated by the same reference numerals, and description thereof will be omitted. In FIG. 1, reference numeral 17 is an optical folding portion, 10B is an optical switch head portion B, and 10C is an optical switch head portion C.

Next, the optical signal from the light source unit 1b of the internal station transmission device is folded back to obtain the light receiving unit 1c of the internal transmission device.
An example of inserting into will be described with reference to FIG. The optical signal from the light source unit 1b of the intra-station transmission device is branched to the optical fiber 24a in the optical coupler / splitter 9a of the transmission side line. When the optical connector a and the head portion B of the optical switch 10 and the optical connector c and the head portion C of the optical switch 10 are connected, the optical signal branched to the optical fiber 24a passes through the optical folding portion 17. After being returned to the optical fiber 24c, it is inserted into the optical fiber 8 in the receiving side via the receiving side optical multiplexer / demultiplexer 9b, and finally returned to the light receiving section 1c of the intra-station transmitting device. The CPU 12 program-controls the optical pulse test apparatus 11, the optical switch 10, and the database 13, and performs a loopback test, a loop 2 (23) test, or an optical pulse test apparatus 11 at the optical line level after being folded back by the optical switch 10. The test is combined and the failure location is determined and displayed.

Next, the test operation according to the present invention will be described with reference to FIGS. 1, 2 and 3. When it is detected that an abnormality has occurred in the optical transmission system by the alarm from the intra-station transmission device 1 or the notification from the communication service user (step SB1), the power of the out-site transmission device 4 is manually turned off (step SB2). .. Next, the inspector uses the optical switch 10 to turn the light back on (step S
B3), an optical loop test is performed (step SB4).
Next, in step SB5, it is determined whether or not the result of the optical loop test is normal.

When a result of "NO" is obtained in step SB5, the optical multiplexer / demultiplexer 9 causes the digital exchange 1 to be switched.
It is determined that the 8 side has a failure (step SB6), and then
A conventional loop 1 test is performed (step SB7). Then, in step SB8, it is determined whether or not the result of the loop 1 test is normal. When a result of "YES" is obtained in step SB8, it is determined that the section from the loop 1 turning point 19 to the optical coupler / splitter 9 points is in failure (step SB9). On the other hand, when a result of "NO" is obtained in step SB8, it is determined that the digital exchange 18 side has a failure from the loop 1 turning point 19 (step SB10).

On the other hand, in step SB5, "YE
When the result of "S" is obtained, since the digital switch 18 side is normal from the 9-point optical multiplexer / demultiplexer, the fault isolation test of the equipment outside the office is performed (step SB11). In step SB11, the optical pulse tester 11 tests the optical filter type sever 6a on the transmitting side external optical fiber 3. Next, the process proceeds to step SB12 shown in FIG. 3 to determine the failure of the optical filter type divisor 6a. As a result of the determination in step SB12, “NO”
When it is determined that the optical fiber 3 outside the transmitting station is out of order, it is separated (step SB13).

On the other hand, in step SB12, "YE
When it is determined to be "S", the process proceeds to step SB14, and the test of the optical filter type splitter 6a on the receiving side external optical fiber 7 is performed. Then, in step SB15, the failure determination of the optical fiber outside the station is performed. When the result of the determination in step SB15 is "NO", it is determined that the receiving side out-of-station fiber 7 is in failure (step SB16). On the other hand, when it is determined as "YES" in step SB15, it is determined that the outside transmission device 4 or the terminal device 5 is out of order (step SB17). Outer station transmission device 4 and terminal device 5
In order to isolate the failure of (1), the conventional loop 2 test is performed (step SB18).

Then, in step SB19, it is determined whether or not the result of the loop 2 test is normal. When "YES" is determined in the step SB19,
The process proceeds to step SB21, and it is determined that the terminal device 5 or the T point 15 is out of order. On the other hand, when it is determined as "NO" in step SB19, the outside station transmission device 4
Is determined to be a failure (step SB20).

As is apparent from the above description of the fault isolation flow, since the test of the loop 1 turning point 19 to the optical multiplexer / demultiplexer 9 which could not be tested up to now can be carried out, the conventional technique shown in Table 1 is used. In comparison with the conventional technology, the internal transmission equipment can perform a loopback test at the optical level including the optical fiber in the office. In addition, 100% failure isolation can be realized.

(Second Embodiment) Next, a second embodiment of the present invention will be described. FIG. 4 is a diagram for explaining the second embodiment of the present invention, in which an optical switch for simultaneously connecting a plurality of optical fibers by a multi-core optical connector and an optical fiber of the connected multi-core optical connector are selected. The optical switch 10 is different from that of the first embodiment in that the optical switch 10 is configured by an optical switch that connects the single-core optical fiber and an arbitrary test device of a plurality of test devices. 4, parts corresponding to the respective parts in FIG. 9 are designated by the same reference numerals, and description thereof will be omitted.

In FIG. 4, reference numeral 28 is a 1 × N optical switch head driving unit, 29 is a guide pin, 30 is a guide hole,
31 is an L × M optical switch (L and M are natural numbers), 32A,
32B and 32C are head connector 3 and 3 respectively.
2a, 32b and 32c are optical connectors, 3
3 is an L × M optical switch head driving unit, 34a, 34b,
34 c and 34 d are optical fibers, 34 is a communication light blocking filter that blocks communication light and transmits test light having a wavelength different from the communication light, 36 is an optical fiber cable, 35 is the CPU 12, and 1 × N optical switch 26, It is a control line for controlling the L × M optical switch 31 and the optical pulse test apparatus 11.

Next, the operation of the second embodiment will be described with reference to FIG. In this figure, the transmission side optical fiber 3
When an optical transmission system using the receiving side optical fiber 7 and the receiving side optical fiber 7 as a transmission line fails, an optical signal from the light source unit 1b of the internal transmission device is transmitted to the optical fiber 3 by the transmitting side optical multiplexer / demultiplexer 9a.
Branch to 4a. On the other hand, the L × M optical switch head drive unit 33 is moved to a position where the head connector 32A and the optical connector 32a and the head connector 32B and the optical connector 32b can be connected to connect the respective optical ports. Further, the 1 × N optical switch head drive unit 28 is moved to a position where the head connector 27A and the optical connector 27a can be connected and connected.

In this connection, the final alignment is adjusted by the guide pins 29 attached to the head connector 27A and the guide holes 30 of the optical connector 27a in the matrix part. Thereby, the above-mentioned optical fiber 34a
The optical signal branched to is the optical connector 27a of the 1 × N optical switch 26, the head connector 27A, and the L × M optical switch 3
The first optical connector 32a passes through the head connector 32A and is returned by the optical return unit 17.

Next, the optical signal is sent to the L × M optical switch 31.
Head connector 32B, optical connector 32b, 1 × N
After passing through the head connector 27A and the optical connector 27a of the optical switch 26, the optical fiber is inserted from the optical fiber 34c into the optical fiber 8 in the receiving side via the receiving side optical multiplexer / demultiplexer 9b. As described above, with the configuration of the 1 × N optical switch 26 and the L × M optical switch 31 having the optical folding unit 17, a loop at the optical level of the intra-station transmission device 1 can be realized. The loopback test, which cannot be realized at the level of the optical module including the unit 1b and the light receiving unit 1c, can be easily realized.

Next, in the case of confirming the presence or absence of a failure of the receiving side external optical fiber 7 by the optical pulse test apparatus 11, the 1 × N optical switch 26 and the L × M optical switch 31.
The operation will be described with reference to FIG. First, in the L × M optical switch 31, the L × M optical switch head drive unit 33
To drive the head connector 32C and the optical connector 32d.
, And the optical connector 27a of the 1 × N optical switch 26 and the head connector 27A are further connected. As a result, the optical pulse sent from the optical pulse test apparatus 11 is L ×
M optical switch 31, head connector 32C and optical connector 32d, 1 × N optical switch 26, optical fiber 34d,
The signals are transmitted in the order of the receiving-side optical multiplexer / demultiplexer 9b and inserted into the receiving-side external optical fiber 7. The optical pulse inserted into the receiving side out-of-station optical fiber 7 reaches the optical filter type splitter 6a installed on the receiving side out-of-station optical fiber 7 in the vicinity of the light source section 4b of the outside-side transmission device 4.

Here, the optical pulse is reflected by the optical filter type divider 6a, and returns as a reflected optical signal in the traveling path of the optical pulse described above. In the above state, the optical signal from the light source unit 4b of the outside station transmitter 4 communicates via the receiving side optical multiplexer / demultiplexer 9b, the 1 × N optical switch 26 and the L × M optical switch 31 in the same manner as the reflected optical signal. Light is transmitted to 34 points of the light blocking filter. At the point 34 of the communication light blocking filter, the optical signal from the light source unit 4b of the outside transmission device is blocked and the reflected optical signal passes. As a result, only the reflected light signal reaches the optical pulse test apparatus 11 and is subjected to signal analysis, so that it is possible to test whether or not there is a failure in the receiving side external optical fiber 7.

As is apparent from the operation of the 1 × N optical switch 26 and the L × M optical switch 31 described above, 1 × N optical switch 26
When the head section connector 27A of the N optical switch is composed of an X-core multi-core optical connector, the configuration of the 1 × N optical switch 26 and the L × M optical switch 31 results in L to M / N /
Since X (integer number) optical switches can be performed, the effect of the second embodiment is that the loopback test and the test of a large number of transmission lines of the intra-office transmission device 1 of a large amount can be realized as compared with the first embodiment, and L By adding the head connector of the × M optical switch 31, a plurality of test devices can be added.

(Third Embodiment) Next, a third embodiment of the present invention will be described. FIG. 5 is a diagram for explaining the third embodiment of the present invention, in which a 1 × 2 optical switch 36 for blocking an optical signal from the light source section 4b of the transmission device outside the office is provided on the receiving side outside optical fiber 7. The point of installation is different from that of the first embodiment. Figure 5
In FIG. 1, parts corresponding to those in FIG. 1 are designated by the same reference numerals, and their description will be omitted. In FIG. 5, reference numeral 3
Reference numeral 6 is the 1 × 2 optical switch, and 37 is a terminal processing port. The 1 × 2 optical switch 36 is installed in the vicinity of the receiving-side optical multiplexer / demultiplexer, and in the state where communication is performed between the office-inside transmission apparatus 1 and the office-outside transmission apparatus 4, the receiving-side outside station optical fiber 7 is connected. Set the connection status. On the other hand, during the loopback test at the optical level, the receiving side out-of-station optical fiber 7 is automatically disconnected by connecting the receiving side out-of-station optical fiber 7 and the terminal processing port under the control of the CPU 12. is there.

Next, the operation of the third embodiment of the present invention will be described with reference to FIGS. 6 and 7. Internal station transmission device 1
When it is detected that an abnormality has occurred in the optical transmission system by an alarm from the user or a notification from the communication service user (step SC1), the 1 × 2 optical switch 36 causes
The optical fiber 7 outside the receiving station is automatically disconnected (step SC2). As a result, it is possible to prevent the optical signal looped back from the light source unit 1b of the intra-station transmission device to the receiving-side intra-station optical fiber 8 during the optical level loopback test and the optical signal from the light source unit 4b of the external transmission device to be prevented from being mixed. it can.
The subsequent fault isolation flow is the same as the operation after step SB3 in the flowcharts shown in FIGS.

Next, the inspector turns the optical switch 10 into the optical folded state and loops the optical fiber of the optical transmission system (step SC3). Next, in step SC4, an optical loop test is performed. Then, step SC5
At, it is determined whether or not the result of the optical loop test is normal. When a "NO" result is obtained in step SC5, it is determined from the optical multiplexer / demultiplexer 9 that the digital switch 18 side has failed (step SC6), and then the conventional loop 1 test is performed (step SC
7). Then, in step SC8, the loop 1
Determine if the test results are normal. When a result of "YES" is obtained in step SC8,
The section from the loop 1 turning point 19 to the optical multiplexer / demultiplexer 9 is cut out as a failure (step SC9). On the other hand, when a result of "NO" is obtained in step SC8, the loop switching point 19 from the loop 1 turning point 19 to the digital exchange 18
The side determines that there is a failure (step SC10).

On the other hand, in step SC5, "Y
When the result of "ES" is obtained, since the digital switch 18 side is normal from the 9-point optical multiplexer / demultiplexer, step SC
Proceed to 11 to conduct a fault isolation test for equipment outside the station.
That is, in step SC11, the optical pulse test apparatus 11
Thus, the test of the optical filter type slicing device 6a on the transmitting side external optical fiber 3 is carried out. Then, step SC12
At, the failure determination of the optical fiber outside the transmitting station is performed. When the result of the determination in step SC12 is "NO", it is determined that the optical fiber 3 outside the transmission side has a failure (step SC13).

On the other hand, in step SC12, "YE
When it is determined to be "S", a test of the optical filter type divisor 6a on the receiving side out-of-station optical fiber 7 is performed (step S).
C14). Then, in step SC15, a failure determination of the receiving side outside station optical fiber is performed. As a result of the determination, when it is determined to be “NO”, the receiving side external optical fiber 7
It is determined that the above is a failure (step SC16).
On the other hand, when it is determined to be "YES" in step SC15, it is determined that the outside station transmission device 4 or the terminal device 5 is out of order (step SC17). In order to isolate the failure of the outside station transmission device 4 and the terminal equipment 5, the conventional loop 2 test is performed (step SC1).
8). Then, in step SC19, it is determined whether or not the result of the test is normal. The step SC19
When it is determined to be “YES”, it is determined that the terminal device 5 or the T point 15 is defective (step SC2
1) When it is determined to be "NO", it is determined that the outside office transmission device 4 is out of order (step SC20).

As is clear from the above description of the fault isolation test flow, in the above embodiment, the 1 × 2 optical switch 36 is installed in the vicinity of the optical multiplexer / demultiplexer 9b on the receiving side to perform the loopback test by the optical loopback switch. At the same time, since the optical signal from the light source unit 4b of the outside station transmitter can be automatically shut off, it is not necessary for the operator to turn off the power source of the outside station transmitter 4, and automation can be performed for all the test items described above. ..

(Fourth Embodiment) Next, a fourth embodiment of the present invention will be described. FIG. 8 is a diagram for explaining a fourth embodiment of the present invention, which is different from the first embodiment in that the optical folding section 17 has a function of amplifying and attenuating an optical signal. In FIG. 8, reference numeral 38 is an optical signal folding device. The optical signal folding device 38 is controlled by the CPU 12 and amplifies or attenuates the folded signal according to the levels of the light source and the light receiving portion of the optical transmission device.

Next, the conditions for amplifying and attenuating the optical signal will be described. In FIG. 8, the light output level in the light source unit 1b of the office internal transmission device is P1 [dBm], and the light receiving level range in the light receiving unit 1c is P2 to P3 [dBm] (however, P
2> P3), passing from the light source unit 1b of the office internal transmission device to the optical folding device 38 and receiving the light receiving unit 1c of the office internal transmission device.
Let L1 be the amount of light loss until reaching
In the case of 1> P2, the optical input level of the loopback signal received by the light receiving section 1c of the office internal transmission device is higher than the allowable range of the received light level, so that the optical input level in the optical folding device 38 is P2 to P3 [. It is necessary to attenuate so as to fall within the range of [dBm].

On the other hand, in the case of P1-L1 <P3, the optical input level of the loopback signal received by the light receiving section 1c of the internal transmission device is lower than the allowable range of the received light level. Optical input level P2-P
It is necessary to perform amplification so that the range is 3 [dBm].
As described above, since the optical signal folding device 38 can amplify or attenuate the optical signal according to the transmission or reception level of the transmission system, a loopback test at the optical level can be performed on many types of transmission devices. It is effective in that it can be done, and the other is the same.

[0049]

As described above, according to the present invention, the failure of the outside transmission device and the above optical transmission line of the optical transmission system including the inside transmission device, the optical transmission line and the outside transmission device. In a fault isolation method for an optical transmission system in which a test is performed by an optical pulse test device, an optical signal transmitted from a light source unit provided in the office internal transmission device is branched via an optical multiplexer / demultiplexer on the optical transmission line. , The branched optical signal is returned by an optical return switch, and further inserted into the optical transmission line via an optical add / drop device to perform a line-level return test and to combine pulsed light from the optical pulse tester The position or amount of pulsed light reflection by the optical filter type splitter placed in the vicinity of the local transmission device of the optical transmission line via a branching device is determined when the optical transmission line is normal. By comparing with the measured position or quantity, it is determined whether or not there is a failure in the optical transmission line, and fault isolation is performed based on the result of the line level loopback test and the result of the failure determination of the optical transmission line. As a result, we quickly conducted a test of the internal transmission device and the optical transmission line,
Moreover, there is an advantage that the fault isolation can be performed 100% as the demarcation point of the telecommunication equipment and the user equipment.

According to the third aspect of the invention, at the time of the loopback test, an optical switch installed on the optical transmission line outside the station on the receiving side shuts off the optical signal from the light source unit of the outside station transmission device. Therefore, there is an advantage that the failure test of the optical transmission system can be automatically performed. Further, according to the inventions of claims 4 and 5, in the folding part of the optical folding switch means, the amplifying means for compensating the passing light loss of the optical multiplexer / demultiplexer and the optical switch, or the light source part of the outside transmission device is provided. Since the attenuating means for compensating for the level gap between the light emitting level and the light receiving level of the light receiving section is provided, optical folding back is performed corresponding to the optical transmission level and the optical reception level of many kinds of intra-station transmission devices. The advantage is that it can be realized.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an optical folding switch according to a first embodiment of the present invention.

FIG. 2 is a flowchart showing a fault isolation procedure according to the first embodiment of the present invention.

FIG. 3 is a flowchart showing a fault isolation procedure of the first embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration of an optical folding switch according to a second embodiment of the present invention.

FIG. 5 is a block diagram showing a configuration of an optical switch that blocks an optical signal from an outside office transmission apparatus according to a third embodiment of the present invention.

FIG. 6 is a flowchart showing a fault isolation procedure according to the third embodiment of the present invention.

FIG. 7 is a flow chart showing a fault isolation procedure of the third embodiment of the present invention.

FIG. 8 is a block diagram showing a configuration of an optical folding switch having an optical signal amplifying / attenuating function according to a fourth embodiment of the present invention.

FIG. 9 is a block diagram showing a configuration of a conventional optical transmission line fault isolation device.

FIG. 10 is an explanatory diagram showing a loopback point of a loopback test at a conventional line level in an optical transmission system.

FIG. 11 is a flowchart showing a fault isolation flow according to a conventional technique in the optical transmission system.

[Explanation of symbols]

 1 Intra-station transmission device 2 Transmission-side in-station optical fiber (transmission path) 3 Transmission-side out-of-station optical fiber (transmission path) 4 Out-of-station transmission device 6a Optical filter type splitter 6b Optical filter type splitter 7 Receiving side outside station Optical fiber (transmission path) 8 Intra-station optical fiber (transmission path) 9a Transmission-side optical multiplexer / demultiplexer 9b Reception-side optical multiplexer / demultiplexer 10 Optical switch (optical switch switching means) 11 Optical pulse test device 20 Transmission-side optical fiber (transmission path) ) 21 optical fiber (transmission path) on receiving side 34 communication light blocking filter 35 control line 36 1 × 2 optical switch (blocking means) 38 optical signal folding device (optical folding unit)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ikuaki Tanaka 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation

Claims (5)

[Claims] 1. A failure of an optical transmission system in which an optical pulse test apparatus performs a failure test on the external transmission apparatus and the optical transmission path of an optical transmission system including an internal transmission apparatus, an optical transmission line, and an external transmission apparatus. In the dividing method, the optical signal being transmitted from the light source unit provided in the office internal transmission device is branched via an optical multiplexer / demultiplexer on the optical transmission path, and the branched optical signal is returned by an optical return switch. Further, the optical fiber is inserted into the optical transmission line through an optical multiplexer / demultiplexer to perform a line-level loopback test, and the pulsed light from the optical pulse test device is transmitted to the outside of the optical transmission line via the optical multiplexer / demultiplexer. By comparing the position or amount of pulsed light reflection by the optical filter type divider arranged near the transmission device with the position or amount measured during normal operation of the optical transmission line. The optical transmission system is characterized in that the presence or absence of a failure in the optical transmission line is determined, and fault isolation is performed based on the result of the line-level loopback test and the result of the failure determination in the optical transmission line. Fault isolation method. 2. A failure cutoff of an optical transmission system in which an optical pulse test device performs a failure test of the outside transmission apparatus and the optical transmission line of an optical transmission system including an inside transmission apparatus, an optical transmission line and an outside transmission apparatus. In the split test device, during the line level loopback test, the optical signal transmitted from the light source unit of the internal transmission device to the optical transmission line is drawn, and the drawn optical signal is returned to return the optical transmission line. In addition to inserting into the optical transmission line, in the failure test of the optical transmission line, the pulsed light from the optical pulse test device is inserted into the optical transmission line, and reflected by the dividing means provided in the optical transmission line. The optical return switch means for supplying the reflected light of the optical pulse to the judgment means, and the failure isolation is performed based on the result of the line level return test and the result of the failure test of the optical transmission line. Failure switching diverging device of the optical transmission system characterized by comprising a failure switching division means. 3. An optical switch installed on the optical transmission line outside the station on the receiving side, and interrupting the optical signal from the light source section of the transmission apparatus outside the station during the loopback test. 2. A fault isolation device for an optical transmission system according to 2. 4. The optical return switch means is provided with an amplifying means for amplifying the optical signal in the return section of the optical signal in order to compensate the passing light loss of the optical multiplexer / demultiplexer and the optical switch. The fault isolation device for an optical transmission system according to claim 2. 5. The optical return switch means attenuates an optical signal in its return portion in order to compensate a level gap between a light emitting level of a light source section and a light receiving level of a light receiving section of the outside office transmission device. 3. The fault isolation device for an optical transmission system according to claim 2, further comprising: