JP2011142495A - Optical fiber line monitoring system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical fiber line monitoring system which can detect "micro bending loss" in OPGW (Optical Ground Wire) in real time, and take an early countermeasure. <P>SOLUTION: The optical fiber line monitoring system 100 is composed by including a transmitting side communication apparatus 1 and a receiving side communication apparatus 8 which transceive an optical signal through an optical fiber line 5, optical couplers 2, 7 which are respectively prepared in the transmitting and receiving ends of the respective communication apparatuses 1, 8 to branch optical signals 17 to main optical signals 19 and monitor signals 18, O/E converters 10, 12 which convert the monitoring optical signals 18 branched from the optical couplers 2, 7 to electrical signals, pieces of SVE (Supervisory Equipment) 11, 13 which collect operation information and failure information of the communication apparatuses 1, 8, and transmit them to a communication network 14, an NMS (Network Management System) 15 which manages the compositions of communication network facilities, performance, failure, and works, and optical switchers 3, 6 which bypass the optical fiber line 5 to another optical fiber line 9. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an optical fiber line monitoring system, and more particularly to an optical fiber line monitoring system that monitors a level fluctuation due to a microbending loss of an optical fiber composite ground wire (OPGW) in real time at a remote location.

  In a power security communication network, communication lines are mainly composed of microwave radio and optical fiber communication. In optical fiber communication, an optical fiber composite ground wire (OPGW) and an optical fiber cable are used as communication media.

  FIG. 7 is a view showing an example of a multi-core type OPGW, in which a plurality of UV fibers 53 are arranged around a plurality of tension members 52, the outside is covered with a heat-resistant resin 54, and the whole is further covered with a heat-resistant tape 50. Is covered. In OPGW, in a cold region, water immersed in the OPGW in the winter freezes, and a communication line failure may occur due to “microbending loss” caused by pressing the optical fiber core wire (UV fiber 53). . As a response to this, conventionally, after the occurrence of a failure, we went to the site and determined whether the failure location was a communication device or a communication line. If the failure was a communication line, OTDR (optical pulse tester: see FIG. 5) confirmed the location of the failure. In addition, a circuit detour configuration to other communication routes was performed.

FIG. 8 is a diagram showing a flow of information when a communication device failure occurs in a conventional system. In the conventional system, when a failure occurs in the communication device 40, the failure contact information 41 is transmitted from the communication device 40 to the SVE 42. Then, the failure information is transmitted from the SVE 42 to the monitoring control server 45 of the NMS 48 via the communication network 43. Further, the failure information is transmitted from the monitoring control server 45 to the NMS terminal 47 and the system monitoring panel 46 and displayed on the screen. This system also monitors communication line failures.
Further, as a conventional technique for monitoring a failure of an optical fiber, Patent Document 1 discloses a system that performs an OTDR test by selecting a corresponding optical fiber when a failure of the optical fiber is detected by a monitor signal. Patent Document 2 discloses a monitoring system in which a basic optical fiber connected to an OTDR is configured in a loop shape, and a plurality of sensors are provided in the loop.

JP 2007-71573 A JP 2008-14698 A

However, if OPGW's “microbending loss” occurs from night to early morning, it will be dispatched to the site in response to this, but in many cases the arrival at the site will be during the daytime, so the temperature will rise and freeze. Since the problem was solved and the failure was restored naturally, it was difficult to investigate the cause.
The prior art disclosed in Patent Document 1 is an invention for specifying a failure position after the occurrence of a failure. Since the line state cannot be monitored in real time in an online state, the line down time is increased. There's a problem.
In addition, the conventional technique disclosed in Patent Document 2 has a problem that the length of the optical fiber is increased and the line cost is increased because the backbone optical fiber connected to the OTDR has to be configured in a loop shape. is there.
The present invention has been made in view of such problems, and includes an optical coupler that branches an optical signal to a transmission end and a reception end and extracts a monitor optical signal, and monitors the level of each monitor optical signal by a network operation management apparatus. Thus, an object of the present invention is to provide an optical fiber line monitoring system capable of detecting OPGW "microbending loss" in real time and taking early measures.

In order to solve this problem, the present invention provides an optical fiber line monitoring system that monitors the state of an optical fiber line, and includes at least two optical signals that are transmitted and received via the optical fiber line. A communication device, an optical coupler provided at each of the transmission end and the reception end of each communication device, for branching the optical signal into a main optical signal and a monitor optical signal, and the monitor optical signal branched by the optical coupler. Manages the configuration, performance, failures, and work of communication network equipment, opto-electric converters that convert to electrical signals, communication monitoring and control devices that collect and transmit operational information and failure information of the communication devices to the communication network A network operation management device, and the network operation management device transmits monitor optical signals transmitted from the transmission side communication device and the reception side communication device, respectively. The level monitor, and judging the state mode based on the combination of the levels.
In the present invention, an optical coupler for branching an optical signal into a main optical signal and a monitor optical signal is provided at each of a transmission end and a reception end of two communication devices connected by an optical fiber line, and the monitor optical signal is an electrical signal. And sent to the communication monitoring and control device, and from there to the network operation management device via the communication network. Then, the network operation management apparatus monitors the level of the monitor optical signal transmitted from each of the transmission side communication apparatus and the reception side communication apparatus, and determines the state mode based on the combination of each level. As a result, it is possible to detect OPGW "microbending loss" in real time and take early measures.

According to a second aspect of the present invention, in the network operation management device, when the levels of the monitor optical signals transmitted from the transmission side communication device and the reception side communication device are both equal to or higher than a predetermined threshold level, the transmission side communication device And determining that the optical fiber line is normal.
The main optical signal transmitted from the transmission side communication device reaches the reception side communication device through the optical fiber line. Here, if the optical fiber line is normal, the levels of the monitor optical signal on the transmission side and the monitor optical signal on the reception side are lowered on the reception side by the attenuation of the line. By determining this level by the network operation management apparatus, it is determined that the transmission side communication apparatus and the optical fiber line are normal. Thereby, the state of a transmission side communication apparatus and an optical fiber line can be judged simultaneously.
According to a third aspect of the present invention, in the network operation management apparatus, the level of the monitor optical signal transmitted from the transmission side communication apparatus is equal to or higher than a predetermined threshold level, and the level of the monitor optical signal transmitted from the reception side communication apparatus is When it is below a predetermined threshold level, it is determined that the transmission side communication device is normal and the optical fiber line is abnormal.
The main optical signal transmitted from the transmission side communication device reaches the reception side communication device through the optical fiber line. If something abnormal (for example, microbending loss) occurs in the optical fiber line, the monitor optical signal on the transmission side is at a normal level, but the level of the monitor optical signal on the reception side is attenuated by the line and decreases. By determining this level by the network operation management apparatus, it is determined that the transmission side communication apparatus is normal and the optical fiber line is abnormal. Thereby, the state of a transmission side communication apparatus and an optical fiber line can be judged simultaneously.

According to a fourth aspect of the present invention, when the level of the monitor optical signal transmitted from the transmission side communication device and the reception side communication device is equal to or lower than a predetermined threshold level, the network operation management device is abnormal in the transmission side communication device. It is determined that it exists.
When the monitor optical signal becomes lower than the threshold level for some reason by the transmission side communication device, in most cases, the level of the main optical signal also becomes lower than the threshold level. Therefore, when the main signal of that level reaches the receiving side via the optical fiber line, the monitoring optical signal on the receiving side is always below the threshold level. From this result, it cannot always be determined that the optical fiber line is also normal. This is because the same phenomenon occurs even if the optical fiber line is disconnected. Accordingly, at this time, it is determined that only the transmission side communication device is abnormal. Thereby, the state of a transmission side communication apparatus and an optical fiber line can be separated and determined.
According to a fifth aspect of the present invention, the transmission-side communication device and the reception-side communication device each include an optical switch that bypasses the optical fiber line to another optical fiber line, and the network operation management device is configured so that the optical fiber line is abnormal. When it is determined that there is an alarm, a warning is issued and a signal for switching the optical fiber line to the other optical fiber line is transmitted to each optical switch.
If it is detected that the optical fiber line is abnormal, the line is blocked until the optical fiber line is repaired. As a result, since communication is interrupted, in the present invention, an optical switching device that bypasses the optical fiber line to another optical fiber line is provided in each of the transmission side communication device and the reception side communication device. When the network operation management apparatus determines that the optical fiber line is abnormal, the network operation management apparatus issues a warning and transmits a signal for switching the optical fiber line to another optical fiber line to each optical switch. Thereby, disruption of communication can be minimized.

According to the present invention, an optical coupler for branching an optical signal into a main optical signal and a monitor optical signal is provided at each of a transmission end and a reception end of two communication devices connected by an optical fiber line, and the monitor optical signal is transmitted. It is converted into an electric signal, sent to the communication monitoring and control device, and then transmitted to the network operation management device via the communication network. Then, the network operation management device monitors the level of the monitor optical signal transmitted from each of the transmission side communication device and the reception side communication device, and determines the state mode based on the combination of each level. It is possible to detect "microbending loss" and take early measures.
If the optical fiber line is normal, the levels of the monitor optical signal on the transmission side and the monitor optical signal on the reception side are reduced on the reception side by the attenuation of the line. By determining this level by the network operation management device, it is determined that the transmission side communication device and the optical fiber line are normal, and therefore the state of the transmission side communication device and the optical fiber line can be simultaneously determined.

Further, when microbending loss occurs in the optical fiber line, the monitor optical signal on the transmission side is at a normal level, but the level of the monitor optical signal on the reception side is attenuated and lowered by the line. By determining this level by the network operation management apparatus, it is determined that the transmission side communication apparatus is normal and the optical fiber line is abnormal, so that the state of the transmission side communication apparatus and the optical fiber line can be determined simultaneously.
When the monitor optical signal is below the threshold level for some reason, the main optical signal level is also below the threshold level in most cases. Therefore, when the main signal of that level reaches the receiving side via the optical fiber line, the monitoring optical signal on the receiving side is always below the threshold level. Accordingly, at this time, since it is determined that only the transmission side communication device is abnormal, it is possible to determine the state of the transmission side communication device and the optical fiber line separately.
Moreover, the transmission side communication apparatus and the reception side communication apparatus are each provided with the optical switch which detours an optical fiber line to another optical fiber line. And when the network operation management device determines that the optical fiber line is abnormal, it issues a warning and transmits a signal for switching the optical fiber line to another optical fiber line to each optical switch. Communication disruption can be minimized.

It is a block diagram which shows the structure of the optical fiber line monitoring system which concerns on embodiment of this invention. It is a figure which shows an example of the monitor optical signal displayed on the display 16 of NMS15. It is a flowchart explaining operation | movement of the optical fiber track | line monitoring system of this invention. (A) is a diagram when both the communication device on the transmission side and the optical fiber line are normal, (b) is a diagram when the transmission side communication device is normal and the optical fiber line is abnormal, (c) These are figures in case a transmission side communication apparatus is abnormal and an optical fiber line is normal. It is a figure explaining the measurement system principle by OTDR. It is a figure showing the relationship between received light power and propagation time. It is a figure which shows an example of multi-core type OPGW. It is a figure which shows the flow of the information at the time of the communication apparatus failure occurrence in the conventional system.

  Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. However, the components, types, combinations, shapes, relative arrangements, and the like described in this embodiment are merely illustrative examples and not intended to limit the scope of the present invention only unless otherwise specified. .

  FIG. 1 is a block diagram showing a configuration of an optical fiber line monitoring system according to an embodiment of the present invention. The optical fiber line monitoring system 100 includes a transmission side communication device 1 and a reception side communication device 8 that transmit and receive optical signals via the optical fiber line 5, and a transmission end and a reception end of each of the communication devices 1 and 8, respectively. The optical couplers 2 and 7 branch the optical signal 17 into the main optical signal 19 and the monitor optical signal 18, and the O / E converter that converts the monitor optical signal 18 branched by the optical couplers 2 and 7 into an electrical signal. (Photoelectric converters) 10 and 12, SVE (Supervisory Equipment) (communication supervisory control devices) 11 and 13 that collect operation information and failure information of the communication devices 1 and 8 and transmit them to the communication network 14, and communication Network management system (NMS) 15 for managing the configuration, performance, failure, and work of network equipment, and light that bypasses the optical fiber line 5 to another optical fiber line 9 And exchangers 3,6, and is configured with a.

Further, the NMS 15 includes a display 16 that displays a failure information and a real-time state of the monitor light signal, and an alarm device 24 that issues an alarm. Then, the NMS 15 monitors the level of the monitor optical signal 18 transmitted from each of the transmission side communication device 1 and the reception side communication device 8, and determines the state mode based on the combination of each level. In FIG. 1, the communication device 1 is a transmission side, the communication device 8 is a reception side, and they are connected by a single optical fiber line 5. There is an optical fiber line on the receiving side. Further, although the optical couplers 2 and 7 are connected to one optical fiber line 5, one may be provided for each tension member 52 shown in FIG.
That is, in the present embodiment, the light that splits the optical signal 17 into the main optical signal 19 and the monitor optical signal 18 at the transmitting end and the receiving end of each of the two communication devices 1 and 8 connected by the optical fiber line 5. Coupled with the couplers 2 and 7, the monitor optical signal 18 is converted into an electrical signal, sent to the SVE 11, and then transmitted to the NMS 15 via the communication network 14. Then, the NMS 15 monitors the level of the monitor optical signal 18 transmitted from each of the transmission side communication device 1 and the reception side communication device 8, and determines the state mode based on the combination of each level. As a result, it is possible to detect OPGW “microbending loss” in real time and take early measures.

  FIG. 2 is a diagram showing an example of the monitor optical signal displayed on the display 16 of the NMS 15. The vertical axis represents the light level (dBm) of the monitor light signal, and the horizontal axis represents time. Reference numeral 20 in FIG. 2 is a plot of the maximum value of the monitor optical signal, reference numeral 21 is a plot of the average value of the monitor optical signal, and reference numeral 22 is a plot of the minimum value of the monitor optical signal. Here, when the threshold value 23 is set to −57.4 dBm, the average value 21 becomes equal to or less than the threshold value 23 at 0:25, and becomes equal to or more than the threshold value 23 at 0:55. As described above, in this system, since the level change of the monitor optical signal is displayed on the display 16 in real time, the state change of the optical fiber line 5 can be grasped in advance, and an early countermeasure can be taken.

FIG. 3 is a flowchart for explaining the operation of the optical fiber line monitoring system of the present invention. The same operations will be described with the same reference numerals. In the figure, the transmission side, the reception side, and the NMS side are shown separately. Data is transmitted from the transmission-side communication device 1 via the optical fiber line 5 (S1). The receiving side communication device 8 receives the data (S1a). Thereafter, the transmission side and the reception side perform the same operation. That is, the monitor optical signal 18 is taken out by the optical couplers 2 and 7 (S2), the photoelectric conversion is performed by the O / E converters 10 and 12 (S3), the signal is input to the SVE 11, and the communication network 14 is input by the SVE 11 Transmit (S4).
The NMS 15 receives the monitor optical signal 18 from the transmission side and the reception side via the communication network 14 and displays it on the display 16 (S5). At that time, the NMS 15 checks whether or not the monitor light signal on the transmission side is equal to or higher than a predetermined threshold level (S6). If the monitor light signal is equal to or higher than the predetermined threshold level (Y in S6), it is checked whether the monitor light signal on the receiving side is equal to or higher than the predetermined threshold level (S7). If the monitor optical signal is equal to or higher than the predetermined threshold level (Y in S7), it is displayed that the transmission side communication device 1 and the optical fiber line 5 are normal (S14). That is, the main optical signal 19 transmitted from the transmission side communication device 1 is transmitted through the optical fiber line 5 and reaches the reception side communication device 8. Here, if the optical fiber line 5 is normal, the levels of the monitor optical signal 18 on the transmission side and the monitor optical signal 18 on the reception side decrease on the reception side due to the attenuation of the line, but are almost the same level (FIG. 4 ( a)). When the NMS 15 determines this level, it is determined that the transmission side communication device 1 and the optical fiber line 5 are normal. Thereby, the state of the transmission side communication apparatus 1 and the optical fiber line 5 can be judged simultaneously.

  On the other hand, if the monitor optical signal is not equal to or higher than the predetermined threshold level in step S7 (N in S7), the transmission side communication device 1 is normal and the optical fiber line 5 is abnormal (microbending loss at the point 4 in FIG. 1). Is generated (S8), and a signal for switching the optical fiber route 5 to the optical fiber bypass route 9 is transmitted to the optical switches 3 and 6 (S9). Then, the alarm device 24 issues an alarm to the network manager (S10). That is, the main optical signal 19 transmitted from the transmission side communication device 1 is transmitted through the optical fiber line 5 and reaches the reception side communication device 8. If something abnormal (for example, microbending loss) occurs in the optical fiber line 5, the monitor optical signal 18 on the transmission side is at a normal level, but the level of the monitor optical signal 18 on the reception side is attenuated by the line. descend. By determining this level, the NMS 15 determines that the transmission side communication device 1 is normal and the optical fiber line 5 is abnormal. Thereby, the state of the transmission side communication apparatus 1 and the optical fiber line 5 can be judged simultaneously.

  If it is determined in step S6 that the monitor light signal 18 on the transmission side is not equal to or higher than the predetermined threshold level (N in S6), it is checked whether the monitor light signal 18 on the transmission side is equal to or higher than the predetermined threshold level (S11). When the monitor light signal 18 on the receiving side is not equal to or higher than the predetermined threshold level in step S11 (N in S11), it is displayed that the transmission side communication device 1 is abnormal (S12), and the process proceeds to step S10. In other words, when the monitor optical signal 18 falls below the threshold level for some reason, the level of the main optical signal 19 also falls below the threshold level. Therefore, when the main optical signal at that level reaches the receiving side via the optical fiber line 5, the monitoring optical signal 18 on the receiving side is always below the threshold level. From this result, it cannot always be determined that the optical fiber line 5 is also normal. This is because the same phenomenon occurs even if the optical fiber line 5 is disconnected. Therefore, at this time, it is determined that only the transmission-side communication device 1 is abnormal. Thereby, the state of the transmission side communication apparatus 1 and the optical fiber line 5 can be separated and determined.

If the monitor light signal 18 on the reception side is equal to or higher than the predetermined threshold level in step S11 (Y in S11), the monitor light signal is detected due to an abnormality in the optical coupler 7 although the transmission side optical signal is output normally. 18 and / or display that the output of the O / E converter 12 is abnormal to give a constant value regardless of the level of the monitor light signal 18 on the receiving side (S13). Step S10 Proceed to That is, the optical couplers 2 and 6 are configured to optically branch the optical signal into the main optical signal 19 and the monitor optical signal 18. For example, it has a configuration like a beam splitter. Therefore, since the light itself is handled, the failure mode of the beam splitter is nothing but the phenomenon that the monitor light signal 18 does not come out at all. As a result, when the monitor light signal 18 on the transmission side is equal to or lower than the threshold value and the monitor light signal 18 on the reception side is equal to or greater than the threshold value, the optical coupler 2 is abnormal even though the optical signal on the transmission side is normally output. It can be considered that the monitor light signal 18 does not come out and / or an abnormality in which the output of the photoelectric converter 12 takes a constant value regardless of the level of the monitor light signal 18 on the receiving side.
Further, when receiving the switching signal from the NMS 15, the optical switches 3 and 6 on the transmission side and the reception side switch the optical fiber line 5 to the optical fiber bypass route 9 (S15).

FIG. 4 is a diagram showing the relationship between the monitor light signal level displayed on the display and the threshold level. 4A is a diagram in the case where both the communication device on the transmission side and the optical fiber line are normal, and FIG. 4B is a diagram in the case where the transmission side communication device is normal and the optical fiber line is abnormal. FIG. 4C is a diagram when the transmission-side communication device is abnormal and the optical fiber line is normal.
In FIG. 4, the threshold levels on the transmission side and the reception side are represented by reference numerals 35 and 36, respectively, the monitor optical signal level on the vertical axis, and the time on the horizontal axis. In the case of FIG. 4A, since the monitor optical signal levels on the transmission side and the reception side are equal to or higher than the threshold levels 35 and 36, it can be said that both the transmission side communication device 1 and the optical fiber line 5 are normal. In the case of FIG. 4B, the monitor-side optical signal level on the transmission side is equal to or higher than the threshold level 35, so that it can be said that the transmission-side communication apparatus 1 is normal, but the monitor-side optical signal level on the reception side is Since the threshold level is 36 or less, the optical fiber line 5 is abnormal. In the case of FIG. 4C, the transmission side monitor optical signal level is equal to or lower than the threshold level 35 at time t1, so the transmission side communication apparatus 1 is abnormal, and the reception side monitor optical signal level is also at time t2. Since it is below the threshold level 36, it can be said that the transmission side communication apparatus 1 is abnormal and the optical fiber line 5 is normal.

  FIG. 5 is a diagram for explaining the principle of a measurement system based on OTDR (“Points of optical fiber technology 200 useful for business”, published by Ohm Co., Ltd., page 295, FIG. 1). The semiconductor laser 26 is modulated by the pulse generator 25, enters the beam splitter 28, and is branched into incident light reflected light. The reflected light is received by the light receiving device 31 and input to the display or recording device 32. Further, it is assumed that the optical fiber 35 to be measured has a connection point 33 and a terminal or break point 34. When light is incident on the optical fiber 35, the light that returns from the middle of the optical fiber 35 to the incident end includes Fresnel reflection caused by steps in the refractive index of the core (incident end, terminal, break point, etc.), and Rayleigh. Among the scattered light, there is backward Rayleigh scattered light (backscattered light) returning to the incident end of the optical fiber 35, and the OTDR utilizing this principle is shown in FIG. (Refer to "Point" distributor Ohm Co., Ltd., page 296, Fig. 2)).

  DESCRIPTION OF SYMBOLS 1 Transmission side communication apparatus, 2 Optical coupler, 3 Optical switch, 4 Microbending loss occurrence place, 5 Optical fiber line, 6 Optical switch, 7 Optical coupler, 8 Reception side communication apparatus, 9 Optical fiber detour route, 10 O / E converter, 11 SVE, 12 O / E converter, 13 SVE, 14 communication network, 15 NMS, 16 display, 17 optical signal, 18 monitor optical signal, 19 main optical signal, 20 maximum value of monitor optical signal, 21 Average value of monitor optical signal, 22 Minimum value of monitor optical signal, 23 Threshold, 24 Alarm device, 100 Optical fiber line monitoring system

Claims (5)

An optical fiber line monitoring system for monitoring the state of an optical fiber line,
At least two communication devices that transmit and receive optical signals via the optical fiber line;
An optical coupler provided at each of a transmission end and a reception end of each of the communication devices, and branching the optical signal into a main optical signal and a monitor optical signal;
A photoelectric converter that converts the monitor optical signal branched by the optical coupler into an electrical signal;
A communication monitoring and control device that collects operation information and failure information of the communication device and transmits them to a communication network;
A network operation management device for managing the configuration, performance, failure, and work of the communication network equipment,
The network operation management apparatus monitors levels of monitor optical signals transmitted from the transmission side communication apparatus and the reception side communication apparatus, and determines a state mode based on a combination of the levels. Track monitoring system.   The network operation management device, when the levels of the monitor optical signals transmitted from the transmission side communication device and the reception side communication device are each equal to or higher than a predetermined threshold level, the transmission side communication device and the optical fiber line The optical fiber line monitoring system according to claim 1, wherein the optical fiber line monitoring system is determined to be normal.   In the network operation management apparatus, the level of the monitor optical signal transmitted from the transmission side communication apparatus is equal to or higher than a predetermined threshold level, and the level of the monitor optical signal transmitted from the reception side communication apparatus is equal to or lower than a predetermined threshold level 2, the optical fiber line monitoring system according to claim 1, wherein the transmission side communication device is determined to be normal and the optical fiber line is abnormal.   The network operation management device determines that the transmission side communication device is abnormal when the level of the monitor optical signal transmitted from the transmission side communication device and the reception side communication device is equal to or lower than a predetermined threshold level. The optical fiber line monitoring system according to claim 1. Each of the transmission-side communication device and the reception-side communication device includes an optical switch that bypasses the optical fiber line to another optical fiber line,
When it is determined that the optical fiber line is abnormal, the network operation management device issues an alarm and transmits a signal for switching the optical fiber line to the other optical fiber line to each optical switch. The optical fiber line monitoring system according to any one of claims 1 to 4, wherein

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