JPH0728266B2 - Optical line test method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention is used in the field of optical communication.

The present invention relates to an optical line test method in an optical transmission method using an optical fiber cable, and more particularly to an optical line test method for testing and monitoring an optical fiber cable without affecting communication even when a communication line is in use.

[Conventional technology]

FIG. 18 is a block diagram showing a conventional method for testing and monitoring an optical fiber cable using a communication line (see Japanese Patent Laid-Open No. 59-166837). In FIG. 18, 1 and 2 are optical transmission terminal stations, 3 is an optical fiber cable, 4 and 5 are optical filters used only by the optical transmission terminal stations 1 and 2, respectively, and an optical filter that passes only light, and 6 is this communication wavelength. Is an optical fiber locator for repeatedly emitting test wavelength light having a different wavelength from, and 7 is an optical branching device.

FIG. 19 shows the insertion loss wavelength characteristics of the optical filters 4 and 5, and has a characteristic of passing only the communication wavelength.

FIG. 20 is an explanatory view showing the insertion loss between the ports of the optical branching device 7, and the loss among the ports a, b and c is shown in Table 1.

The ports a and c are connected to the optical fiber cable 3, and the port b is connected to the optical fiber locator 6. Where ports ac
The insertion loss is 3 dB between bc and 40 dB between a and b, and the communication wavelength light passes from port a to c with relatively low loss, but does not enter port b, that is, the optical fiber locator 6. The test wavelength light emitted from the optical fiber locator 6 is inserted into the ports b to c with relatively low loss. The test wavelength light emitted from the optical fiber locator 6 is inserted into the optical fiber cable 3 via the above-mentioned optical branching device 7 and travels toward the optical transmission terminal station 2. At that time, the backscattered light and the Fresnel reflected light at an arbitrary point of the optical fiber cable 3 return to the optical fiber locator 6 via the optical branching device 7 in the route opposite to the test wavelength light, and their light receiving time and light receiving level. Can be found and the location of the fault identified by continuing to compare Since the test wavelength light and the backscattered light are blocked by the optical filters 4 and 5 and are not received by the optical transmission terminal stations 1 and 2, it is possible to test and monitor the optical fiber cable without affecting communication.

[Problems to be solved by the invention]

However, the above-mentioned conventional optical line test method cannot test and monitor the optical fiber cable 3 between the optical transmission terminal station 1 or the optical filter 4 and the optical branching device 7.

When the transmission method between the optical transmission terminal stations 1 and 2 is the wavelength division multiplexing bidirectional transmission method (for example, F-6M optical transmission method), the communication wavelength light emitted from the optical transmission terminal station 2 is transmitted from the optical branching device 7 to the optical fiber. It enters the locator 6 and measurement becomes impossible.

When the optical fiber cable 3 has a large number of cores, the number of core wires to be tested becomes plural, and it is necessary to change the connection between the optical fiber locator 6 and the optical branching device 7 at each test, and remote automation of measurement cannot be performed.

There was a drawback.

The object of the present invention is to eliminate the above-mentioned drawbacks and to provide a remote-automatic and quick optical fiber cable without affecting the communication signal over the entire optical waveguide section constituted by the optical fiber between the optical transmission terminal stations. An object is to provide an optical line test method capable of testing and monitoring.

[Means for solving problems]

The present invention provides an optical branching unit that is inserted in the middle of an optical fiber cable connected between optical transmission devices and controls insertion of a test wavelength light from the outside into the optical fiber cable; In an optical line test system including a test means including an optical pulse tester for detecting the test wavelength light returned from the optical fiber cable, the optical branching means is inserted at an arbitrary point of the optical fiber cable. 1 × N optical switch for selecting a test line port of the combined / branched waveform optical coupler, and 1 × N thereof. And a control means for performing program control of the optical switch.

Further, the present invention may include a first optical filter inserted in the immediate vicinity of the optical transmission device and a second optical filter inserted in the immediate vicinity of the optical pulse tester.

Further, in the present invention, the first optical filter is a filter having a gentle cutoff characteristic, and the second optical filter can be built in the optical pulse tester.

The present invention also provides a 1 × M optical switch (M is a natural number) inserted between the 1 × N optical switch and the optical pulse tester, and the 1 × M optical switch is connected in parallel with the optical pulse tester. A plurality of optical signal devices including an optical signal monitor device and an optical signal transmission device connected to each other can be included.

The present invention also provides the 1 × N optical switch and the 1 × M optical switch.
N × M optical switches can be used instead of optical switches.

Further, in the present invention, it is preferable that the combined-waveform optical coupler is a wide wavelength range type optical coupler.

[Action]

The combined-waveform optical coupler has four ports, two of which are opposed to each other and are connected to the optical fiber core, and the other two of which are for insertion from the 1 × N optical switch. It is connected to the optical fiber core. The communication wavelength light can pass between the two ports facing each other with almost no loss, and hardly pass through the other two ports. On the other hand, the test wavelength light can pass diagonally to the upper port with almost no loss and almost no light to other ports.

Therefore, if the test wavelength light whose wavelength is different from the communication wavelength light is inserted into one port, the test wavelength light can be inserted into one optical fiber core with almost no loss, and the test wavelength light inserted into the other port is the other. Each of the optical fiber cores can be tested and monitored.

When a wide wavelength range type optical coupler is used as the combined / waveform optical coupler, both the communication wavelength light and the test wavelength light can pass between the ports with constant loss in the wide wavelength range, and these losses are the manufacturing conditions of the coupler. Can be easily set to a desired value by changing. Therefore, any light other than the communication wavelength light can be used as the test wavelength light, and the test and monitoring of the optical fiber cable can be performed more easily.

The 1 × N optical switch switches the insertion of the test wavelength light into the N optical fiber cores under the control of the control means, and the optical pulse tester generates and detects the test wavelength light.
Data processing is performed by the control means.

That is, it is possible to perform remote and rapid test and monitoring without affecting the communication signal over the entire area of the optical fiber cable connected between the optical transmission devices.

Further, the first optical filter is inserted in a configuration in which the test wavelength light does not enter the optical transmission device in the immediate vicinity of the optical transmission device, and the communication wavelength light is transmitted to the optical pulse test device in the immediate vicinity of the optical pulse test device. By inserting the second optical filter in a structure that does not intrude, it is possible to further reduce the influence on the communication signal and improve the accuracy of testing and monitoring.

Further, the level of the test wavelength light of the optical pulse tester is variable by inserting the second optical filter in a configuration in which the communication wavelength light does not enter the optical pulse tester in the immediate vicinity of the light receiver of the optical pulse tester. By adjusting the level of the test wavelength light so that it does not enter the optical transmission device, it is possible to similarly reduce the influence on the communication signal and improve the accuracy of the test and monitoring.

Further, a 1 × M optical switch is inserted between the 1 × N optical switch and the optical pulse tester, and the optical pulse tester, the optical signal monitoring device, and the optical signal are connected to the M port of the 1 × M optical switch. By connecting a sending device and the like and further connecting these remote automation means, the testing and monitoring of the optical communication line can be remotely automated. In this case, similar performance can be obtained by using an N × M optical switch instead of the 1 × N optical switch and the 1 × M optical switch.

Also, combined / waveform optical couplers (including wide wavelength range optical couplers)
Is inserted in the center point of the optical fiber cable, the upper and lower optical fiber cables having the combined waveform optical coupler inserted therein can be tested by operating the 1 × N optical switch. The testable distance can be doubled compared to the conventional one without increasing the dynamic range of.

〔Example〕

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

[Embodiment 1] FIG. 1 is a block diagram showing a first embodiment of the present invention.

In the first embodiment, the upper and lower optical fiber cables 31 and 32 connected between the optical transmission terminal stations 1 and 2 and the optical fiber of the test wavelength light from the outside inserted between the optical fiber cables 31 and 32. N combined-waveform optical couplers 10 as optical branching means for controlling insertion into the cables 31 and 32
And the generation of the test wavelength light and the optical fiber cable
Select the test line port of the N / 2 (N is an even number) combined-waveform optical coupler 10 as a test means including the optical pulse tester 12 for detecting the test wavelength light returned from 31 or 32. It includes a 1 × N optical switch 11, a control device 14 for performing program control and data processing of the 1 × N optical switch 11 and the optical pulse tester 12, and a display device 15.

In addition, 81 and 82 are upper and lower optical fiber core wires, 91, 92, 93 and 94 are ports of the combined optical coupler 10, 83, 84 and 85 are optical fiber core wires for test optical transmission, 13
Is a bus. Here, the 1 × N optical switch 11 has one terminal connected to the optical pulse tester 12, and N terminals connected to the combined / waveform optical coupler 10 for inserting the test wavelength light.
One of these N terminals is selected and connected to the optical pulse tester 12.

The feature of the present invention is that in FIG.
And a control device 14 having a program control means for the 1 × N optical switch 11 is provided.

Next, the operation of the first embodiment will be described. First, a more detailed structure and operation of the combined waveform optical coupler 10 will be described. FIG. 2 is an explanatory diagram showing a concrete example of the configuration of the combined / waveform optical coupler 10, in which 86 and 87 are optical fiber core wires 81 to 81, respectively.
These are a clad portion and a core portion in 84 and the coupler portion 88. This combined-waveform optical coupler 10 has four ports 91 to 94 as shown in FIG. 1, and 91 and 93 are connected to communication optical fiber core wires 81 and 82, respectively.
And 94 are test optical transmission optical fiber cores 83 and 84, respectively.
It is connected to the. Light of communication wavelengths λ _n and λ ′ _n can pass between ports 91 and 93 with almost no loss,
It rarely passes through the other ports 92 and 94. In addition, it has the characteristic that light of the test wavelength λ ₀ can pass between ports 92-93 and ports 94-91 with almost no loss, and it hardly passes from ports 91 to 92 and ports 94 to 93. There is. In the coupler section 88 in FIG. 2, an appropriate distance d and length l are set for the two cores 87 which are optical waveguides.
The evanescent effect idea to maintain, the d and wavelength from _{l λ 0, λ n, λ} ' the value of _n is determined, it occurs demultiplexing characteristics described above. Table 2 shows this combined-waveform optical coupler.
An example of the insertion loss between each of the 10 ports is shown in the figure. A combined-wave optical coupler (fiber type, VWD976
It is the measurement result of 8). When the communication wavelength is 1.3 μm and the test wavelength is 1.55 μm, the insertion loss of the communication wavelength light and the insertion loss of the test wavelength light propagating to the communication core wire are 0.5 dB or less,
Good characteristics with insertion loss of 20 dB or more for all other ports are obtained.

Therefore, the test wavelength light λ ₀ is transmitted from the optical fiber 83 to the port 9
When it is inserted into 2, it is propagated to the port 93 and can be inserted into the lower optical fiber core wire 82, and when inserted from the optical fiber core wire 84 to the port 94, it is propagated to the port 91 and the upper optical fiber core wire 81.
Can be inserted with very little loss.

Next, the operation of the first embodiment will be described. In FIG. 1, the 1 × N optical switch 11 selects a test light insertion port 92 of an arbitrary combined / split optical coupler 10 and connects it to the optical pulse tester 12 by program control from the controller 14. Next, a test light pulse is emitted from the optical pulse tester 12 to measure the loss characteristics of the optical fiber core wire 82 to be tested and detect the failure position.
Further, the 1 × N optical switch 11 selects the test light insertion port 94 and the optical pulse tester 12 performs the same test as described above. By repeating this operation, the upper and lower optical fiber cables 31 of the transmission line between the optical transmission terminal stations 1 and 2
And 32 can be tested and monitored. The level of the test wavelength light transmitted from the optical pulse tester 12 is set smaller than the level of the communication wavelength light so that the optical transmission quality is not deteriorated. Further, the light receiver of the optical pulse tester 12 has a narrow wavelength band so that it does not receive communication wavelength light.

Since such an operation is performed, a test can be performed without affecting communication even in the case of bidirectional transmission with a plurality of communication wavelengths from any position over the entire optical fiber cable between the optical transmission terminal stations 1 and 2.

If the insertion point of the combined waveform optical coupler 10 is set to the center point of the transmission line, the upper and lower optical fiber cables 31 and 32 can be tested by operating the 1 × N optical switch.
The testable distance can be doubled as compared with the conventional one without increasing the dynamic range of the optical pulse tester 12.

Since the 1 × N optical switch 10 is used, a large number of test core wires can be automatically tested by one optical pulse tester 12, so that the device cost and the maintenance cost can be reduced.

As is clear from this result, it is possible to test and monitor the line without affecting communication even in the case of the bidirectional transmission method at any point over the entire optical fiber cable transmission line compared with the conventional technology, and the dynamic of the optical pulse tester. The testable distance can be increased up to 2 times without increasing the range, and many test lines can be automatically tested by one optical pulse tester, and maintenance costs can be reduced.

Second Embodiment FIG. 3 is a block diagram showing the second embodiment of the present invention. The second embodiment is the same as the first embodiment of FIG. 1 except that it is provided between the optical transmission terminal stations 1 and 2 and the optical fiber core wires 81 and 82, and the 1 × N optical switch 11 and the optical pulse tester 12. Optical couplers 10a and 10b are added between the two to reduce the penetration of the test wavelength light into the optical transmission terminal stations 1 and 2 and the communication wavelength light into the optical pulse tester 12.

The feature of the present invention is that in FIG.
And a control device 14 having a program control means for the 1 × N optical switch 11 is provided. Incidentally, the combined waveform optical couplers 10a and 10b are added.

Since the second embodiment has the configuration as described above, it is difficult to give interference to communication even if the test wavelength light transmission level of the optical pulse tester 12 is increased to some extent, and to the optical pulse tester 12 for communication wavelength light. Can be made smaller. Therefore, there is an effect that the dynamic range of the optical pulse tester 12 can be increased. Other effects are similar to those of the first embodiment.

[Embodiment 3] FIG. 4 is a block diagram showing a third embodiment of the present invention. The third embodiment is the same as the first embodiment shown in FIG. 1 between the optical transmission terminals 1 and 2 and the optical fiber core wires 81 and 82, and between the 1 × N optical switch 11 and the optical pulse tester 12. Optical filters 16 and 17 are respectively inserted into the optical transmission terminal stations 1 and 2 to reduce the penetration of the test wavelength light and the optical pulse tester 12 into the communication wavelength light. Here, the optical filter 16 for inserting the test line has a loss characteristic as shown in FIG. 5, and 19, 20 and 21 in FIG. 5 are test wavelengths λ ₀₁ , λ ₀₂ and λ ₀₃ , respectively. That is, it has a characteristic of passing the communication wavelength light and blocking the test wavelength light. Also, 1 × N
The optical filter 17 inserted between the optical switch 11 and the optical pulse tester 12 has a loss characteristic as shown in FIG. 6, and the test wavelengths of 22, 23 and 24 in FIG. ₀₁ , λ
_In the case of ₀₂ and λ ₀₃ , it is a characteristic of passing the test wavelength light and blocking the communication wavelength light.

Since the third embodiment has the above-described configuration, even if the test wavelength light transmission level of the optical pulse tester 12 is increased to some extent, interference with communication is less likely to occur, and the optical pulse tester 12 Even if the light receiving device of (1) is made to have a relatively wide wavelength range to some extent, it is possible to reduce the penetration of communication wavelength light into the optical pulse tester (12).

Therefore, there is an advantage that the dynamic range of the optical pulse tester 12 can be increased. Other effects are similar to those of the first embodiment.

The feature of the present invention is that in FIG.
This is because the 1 × N optical switch 11, the control device 14 having the program control means for the 1 × N optical switch 11, and the optical filters 16 and 17 are provided.

[Embodiment 4] FIG. 7 is a block diagram showing a fourth embodiment of the present invention. In the fourth embodiment, the optical pulse tester 12 in the first embodiment of FIG. 1 is replaced with an optical pulse tester 25 having a variable optical output, and a 1 × N optical switch 11 and an optical pulse tester 25 are used. A coupling / decoupling waveform optical coupler 10b is inserted between them. 8th
The figure shows the light emitting and receiving module (LD module) built in the optical pulse tester 25 to make the test light level variable.
The optical attenuator 27 is inserted into the modification 26, and the modification is made. 29 is an optical circulator, 28 is a light receiving part, 35 is a light emitting part, and 36 is a CPU. The test wavelength light is output from the port 34 of the optical circulator 29.
The received light propagates from port 30 to port 33. With such a configuration, the optical level of the test wavelength light is changed by the optical attenuator 28 to increase the level difference between the communication wavelength light and the test wavelength light in the optical transmission terminal stations 1 and 2, and influence on communication. Can be made smaller.

The effect of the fourth embodiment is that it is not necessary to use the combined waveform optical coupler 10a installed in the immediate vicinity of the optical transmission terminal stations 1 and 2 in the second and third embodiments, so that it is more economical than these embodiments. System configuration is possible. Other effects are similar to those of the second and third embodiments.

The feature of the present invention is that in FIG.
The 1 × N optical switch 11, the control device 14 having the program control means for the 1 × N optical switch 11, and the optical pulse tester 25 of variable test light level are provided. In addition,
A combined-waveform optical coupler 10b is added.

[Fifth Embodiment] FIG. 9 is a block diagram showing the fifth embodiment of the present invention. The fifth embodiment is the same as the fourth embodiment shown in FIG. The filter 17 is inserted, and its operation and effect are similar to those of the fourth embodiment.

The feature of the present invention is that in FIG.
A 1 × N optical switch 11, a control device 14 having a program control means for the 1 × N optical switch 11, and an optical filter 17
And an optical pulse tester 25 of variable test light level.

[Sixth Embodiment] FIG. 10 is a block diagram showing a sixth embodiment of the present invention. The sixth embodiment is the same as the first embodiment shown in FIG. 1, except that the combined wavelength optical coupler 10 is replaced with a wide wavelength range optical coupler 10c, and a database 14a for storing the test results is connected to the controller 14. It was done.

The feature of the present invention is that a wide wavelength range type optical coupler is shown in FIG.
10c, a 1 × N optical switch 11 and a control device 14 having a program control means for the 1 × N optical switch 11 are provided.

Next, the operation of the sixth embodiment will be described. First, a more detailed structure and operation of the wide wavelength range optical coupler 10c will be described. The structure of the wide wavelength range type optical coupler 10c is the same as that of the combined / waveform optical coupler 10 shown in FIG. 2, and 86 and 87 are the optical fiber core wires 81 to 84 and the cladding portion and core portion in the coupler portion 88, respectively. . This wide wavelength type optical coupler 10c
Has four ports 91 to 94 as shown in FIG. 10, and 91 and 93 are optical fiber core wires 81 and 82 for communication, respectively.
, And 92 and 94 are connected to test optical transmission optical fiber cores 83 and 84, respectively. Communication wavelength λ _n
And lambda 'for the light of _n can pass through a wide wavelength range and constant loss between ports 91 and 93. Also, the light of the test wavelength λ _o can pass between the ports 92 and 93 and between the ports 94 and 91 with a wide wavelength range and constant loss. Therefore, the communication wavelength,
The test wavelength can be freely selected over a wide wavelength range. Second
In the coupler section 88 in the figure, two cores that are optical waveguides
When 87 is maintained at an appropriate distance d and length l and the core diameter is slightly changed, an optical coupling characteristic in a wide wavelength region is generated due to the evanescent effect. Table 3 shows an example of the insertion loss between each port of this wide wavelength range optical coupler 10c. Wide wavelength range optical coupler manufactured by Gould, USA (fiber type, WICA type, branching ratio 20:80) Is the result of actual measurement.

Communication port 9193 over a wide wavelength range from 1200 nm to 1650 nm
The loss is 1.5 dB or less, and the loss between the test light insertion ports 92 → 93 and 94 → 91 shows good characteristics of about 6 to 9 dB.

As apparent from the above description, the sixth embodiment performs the same operation as that of the first embodiment.

In addition to the effects of the first embodiment described above, a wide wavelength range optical coupler 10c having the above-mentioned characteristics as a combined / waveform optical coupler.
Therefore, the effect that the wavelengths of the communication wavelength light and the test wavelength light can be freely selected is obtained.

[Seventh Embodiment] FIG. 11 is a block diagram showing a seventh embodiment of the present invention. The seventh embodiment is the same as the sixth embodiment of FIG. 10 except that it is between the optical transmission terminal stations 1 and 2 and the optical fiber cores 81 and 82, and between the 1 × N optical switch 11 and the optical pulse tester 12. Optical filters 16 and 17 are inserted into the optical transmission terminal stations 1 and 2, respectively, to reduce the penetration of the test wavelength light and the optical pulse tester 12 into the communication wavelength light. This corresponds to the third embodiment shown in FIG.

Since the seventh embodiment is configured as described above, even if the test wavelength light transmission level of the optical pulse tester 12 is increased to some extent, it is less likely to interfere with communication, and the light receiver of the optical pulse tester 12 is provided to some extent. Even in a wide wavelength range, it is possible to reduce the amount of communication wavelength light entering the optical pulse tester 12. Therefore, there is an effect that the dynamic range of the optical pulse tester 12 can be increased. Other effects are similar to those of the sixth embodiment.

The feature of the present invention is that a wide wavelength range type optical coupler is shown in FIG.
10c, 1 × N optical switch 11, control device 14 having program control means for the 1 × N optical switch 11, and optical filter
16 and 17 are provided.

[Embodiment 8] FIG. 12 is a block diagram showing an eighth embodiment of the present invention. In the eighth embodiment, the optical pulse tester 12 in the seventh embodiment of FIG. 11 is replaced with an optical pulse tester 25a having a variable optical output type and an optical filter 17 built-in type, and the optical filter 16 has a cutoff characteristic to some extent. Badly loosened optical filter 16a
It was replaced with. FIG. 13 shows an optical attenuator 27 and an optical filter 17 inserted in a light emitting and receiving module 26a incorporated in the optical pulse tester 25a in order to make the test light level variable and to incorporate the optical filter 17. It is a remodeled one, 29 is an optical circulator, 28 is a light receiving part, 35 is a light emitting part, and 36 is a CPU. Test wavelength light is an optical circulator 29
Are inserted into ports 34 to 30 of the
Propagate to. With such a configuration, the optical level of the test wavelength light is changed by the optical attenuator 28, and the level difference between the communication wavelength light and the test wavelength light in the optical transmission terminal stations 1 and 2 is increased, thereby affecting the communication. Can be made smaller. further,
The optical filter 17 cuts off communication light, and a light receiver in a wide wavelength range can be used for the light receiving unit 28.

The effect of the eighth embodiment is that the optical filter 16 installed in the immediate vicinity of the optical transmission terminal stations 1 and 2 in the seventh embodiment is replaced by an optical filter 16a which has poor blocking characteristics and can be manufactured economically. The system can be economically constructed as compared with the embodiment. Other effects are similar to those of the seventh embodiment.

A characteristic of the present invention is that in FIG. 12 and FIG. 13, a controller 14 having a wide wavelength band optical coupler 10c, a 1 × N optical switch 11, and a program control means for the 1 × N optical switch 11 is provided.
And the optical pulse tester 25a of the test light level variable type and the optical filter 17 built-in type.

[Ninth Embodiment] FIG. 14 is a block diagram showing the ninth embodiment of the present invention. The ninth embodiment is the same as the sixth embodiment of FIG.
The 1 × M optical switch 37 is inserted between the × N optical switch 11 and the optical pulse tester 12, and the optical pulse tester 12, the optical signal monitor device 38 and the optical signal are connected to the M port of the 1 × M optical switch 37. Connected to the optical signal device including the sending device 39, and further 1 × N
Optical switch 11, 1 × M optical switch 37, optical pulse tester 1
2. A wide area maintenance center 43 including a modem 40b, an optical line test workstation 42 and a database 14a and a modem 40a are connected by a modem communication line 41 so that the optical signal monitor device 38 and the optical signal transmission device 39 can be operated by remote automation. The remote automation means 44 described above is provided and the display device 15 is removed.

The operation of the ninth embodiment is performed by program control from the optical line work station 42, monitoring of the communication line by the optical signal monitor device 38, transmission of the optical fiber reference light by the optical signal transmission device 39, and the optical pulse tester 12. Communication line testing and monitoring can be remotely automated. Therefore, in addition to the effect that the remote control of the communication line monitor and the optical fiber transmission of the optical fiber at the time of the cable relocation work can be automated, the same effect as the sixth embodiment can be obtained.

The feature of the present invention is that a wide wavelength range type optical coupler is shown in FIG.
10c, 1 × N optical switch 11, 1 × M optical switch 37
The optical pulse tester 12, the controller 14, the optical signal monitor 38, the optical signal transmitter 39, and the remote automation means 44 including the modem 40a and the wide area maintenance center 43 are provided.

[Embodiment 10] FIG. 15 is a block diagram showing a tenth embodiment of the present invention. In the tenth embodiment, the ninth embodiment is applied to the eighth embodiment, and the effects are the same as those of the eighth and ninth embodiments.

The feature of the present invention resides in that in FIG. 15, an optical filter 16a is added to the ninth embodiment of FIG.

[Eleventh Embodiment] FIG. 16 is a block diagram showing the eleventh embodiment of the present invention. This eleventh embodiment is 1 × N of the ninth embodiment shown in FIG.
An N × M optical switch 45 is arranged in place of the optical switch and the 1 × M optical switch 37. Therefore, in the eleventh embodiment, the communication line is simultaneously selected from the devices connected to the M port of the N × M optical switch 45, such as the optical pulse tester 12, the optical signal monitoring device 38 and the optical signal transmitting device 39. In addition to the effect of being accessible, the same effect as the ninth embodiment is obtained.

The feature of the present invention is that a wide wavelength range type optical coupler is shown in FIG.
10c, N × M optical switch 45, optical pulse tester 12,
Control device 14, optical signal monitor device 38, and optical signal transmission device
39 and a remote automation means 44 including a modem 40a and a wide area maintenance center 43.

[Embodiment 12] FIG. 17 is a block diagram showing a twelfth embodiment of the present invention. This twelfth embodiment is 1 × N of the tenth embodiment of FIG.
An N × M optical switch 45 is arranged in place of the optical switch 11 and the 1 × M optical switch 37. Therefore, similar to the eleventh embodiment, the effect that the communication line can be simultaneously selected and accessed from the device connected to the M port of the N × M optical switch 45, and the same effect as the tenth embodiment is obtained. To be

A feature of the present invention is that an optical filter 16a is added to the eleventh embodiment of FIG. 16 in FIG.

In addition, in the second embodiment of FIG. 3, the fourth embodiment of FIG. 7 and the fifth embodiment of FIG. 9, a wide wavelength range optical coupler 10c is used in place of the combined / split optical coupler 10. As a result, the effects added in the sixth embodiment are similarly added.

In the above description of the embodiments, the number of the combined / split optical couplers 10 and the wide wavelength range optical couplers 10c is plural, but the present invention is similarly applied to the case of N = 2, that is, one. It

〔The invention's effect〕

As described above, according to the present invention, it is possible to test and monitor the line without affecting communication even in the case of the bidirectional transmission method at any point over the entire area of the optical fiber cable transmission line as compared with the conventional technique. The testable distance can be increased up to 2 times without increasing the dynamic range of the pulse tester, and more than one test line can be automatically tested by one optical pulse tester. When a band-type optical coupler is used, the wavelengths of the communication wavelength light and the test wavelength light can be selected arbitrarily in a wide wavelength range, which is economical, has a moderate installation condition, and can significantly reduce maintenance costs. A road test method can be provided and its effect is great.

[Brief description of drawings]

FIG. 1 is a block diagram showing the first embodiment of the present invention. FIG. 2 is an explanatory diagram showing the structures of the combined waveform optical coupler and the wide wavelength range optical coupler. FIG. 3 is a block diagram showing the second embodiment of the present invention. FIG. 4 is a block diagram showing the third embodiment of the present invention. FIG. 5 is an insertion loss characteristic diagram of the optical filter 16. FIG. 6 is an insertion loss characteristic diagram of the optical filter 17. FIG. 7 is a block diagram showing the fourth embodiment of the present invention. FIG. 8 is a block diagram showing a light emitting / receiving module of the optical pulse tester. FIG. 9 is a block diagram showing the fifth embodiment of the present invention. FIG. 10 is a block diagram showing a sixth embodiment of the present invention. FIG. 11 is a block diagram showing the seventh embodiment of the present invention. FIG. 12 is a block diagram showing the eighth embodiment of the present invention. FIG. 13 is a block diagram showing a light emitting / receiving module of the optical pulse tester. FIG. 14 is a block diagram showing the ninth embodiment of the present invention. FIG. 15 is a block diagram showing the tenth embodiment of the present invention. FIG. 16 is a block diagram showing the eleventh embodiment of the present invention. FIG. 17 is a block diagram showing the twelfth embodiment of the present invention. FIG. 18 is a block diagram showing a conventional example. FIG. 19 is an insertion loss characteristic diagram of the optical filter 5. FIG. 20 is an explanatory diagram of insertion loss characteristics of the branch device. 1, 2 ... Optical transmission terminal station, 3, 31, 32 ... Optical fiber cable, 4, 5, 16, 16a, 17 ... Optical filter, 6 ... Optical fiber locator, 7 ... Optical branching device, 10, 10a, 10b ...
… Combined-waveform optical coupler, 10c… Wide wavelength range optical coupler, 11
…… 1 × N optical switch, 12, 25, 25a …… Optical pulse tester, 13 …… Bus, 14 …… Control device, 14a …… Database, 15 …… Display device, 19 to 24 …… Optical filter Loss characteristics, 26, 26a ... Emitting and receiving module, 27 ... Optical attenuator, 2
8: Light receiving part, 29: Optical circulator, 30, 33, 34, 9
1-94 …… Port, 35 …… Light emitting part, 36 …… CPU, 37 …… 1
× M optical switch, 38 ... Optical signal monitoring device, 39 ... Optical signal sending device, 40a, 40b ... Modem, 41 ... Modem communication line, 42 ... Optical line test workstation, 43 ... Wide area maintenance center , 44 ... remote automation means, 45 ... NxM optical switch, 81, 82 ... optical fiber core wire, 83, 84, 85 ... optical fiber core wire for inserting test light, 86 ... cladding part, 87 ......
Core part, 88 ... Coupler part.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP 63-193750 (JP, A) JP 59-166837 (JP, A) JP 54-32939 (JP, A)

Claims (6)

[Claims] 1. An optical branching unit which is inserted in the middle of an optical fiber cable (31, 32) connected between optical transmission devices and controls insertion of a test wavelength light from the outside into the optical fiber cable, An optical line test method comprising: a test means including an optical pulse tester (12) for generating a test wavelength light and detecting the test wavelength light returned from the optical fiber cable, wherein the optical branching means is a N / 2 (N is an even number) combined / demultiplexed optical coupler (1
0), and the test means selects a test line port of the combined-waveform optical coupler, a 1 × N optical switch (11), and the 1 × N optical switch (11).
An optical line test method comprising: a control means (14) for performing program control of an optical switch. 2. A first optical filter (16) inserted in the immediate vicinity of an optical transmission device, and a second optical filter (17) inserted in the immediate vicinity of an optical pulse tester. Optical line test method. 3. The optical line testing method according to claim 2, wherein the first optical filter is a filter having a gentle cutoff characteristic, and the second optical filter is built in the optical pulse tester. Optical line test method. 4. A 1 × M optical switch (M is a natural number) inserted between the 1 × N optical switch and the optical pulse tester, and the 1 × M optical switch is connected in parallel with the optical pulse tester. A plurality of optical signal devices including an optical signal monitoring device and an optical signal transmitting device, and remote automation means for performing remote automatic control of operations of the optical pulse tester and the optical signal device. The optical line test method according to any one of 3 above. 5. The optical line test system according to claim 4, wherein an N × M optical switch is used instead of the 1 × N optical switch and the 1 × M optical switch. 6. The optical line test system according to claim 1, wherein the combined-waveform optical coupler is a wide wavelength range type optical coupler.