JP2008232849A - Optical fiber monitoring method and optical fiber monitoring system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively perform a measurement of an optical fiber using OTDR (Optical Time Domain Reflect meter). <P>SOLUTION: To each station in the optical communication network connected by optical fibers 14 between a plurality of mutual stations 1 and 2, the OTDR 4 for performing measurement of transmission reception of optical pulses to the optical fiber are provided. In the optical fiber monitoring method for setting the measurement condition to the OTDR 4 of each station and collecting the measurement results as well, wherein after setting of the measurement condition to the optical fiber 14 being the monitoring object to the OTDR of one station, while the OTDR is performing the measurement to the optical fiber being the monitoring object of the OTDR, the setting of the measurement condition or the collection of measurement results is performed to the optical fiber connected to this OTDR to the other OTDR of the other station. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical fiber monitoring method and an optical fiber monitoring system for monitoring the state of optical fibers connected between stations in an optical communication network in which a plurality of stations are connected with optical fibers.

  An optical fiber monitoring system that monitors the state of optical fibers that connect each station in an optical communication network in which a plurality of stations are connected by optical fibers is configured as shown in FIG. 12, for example.

  The central station 1 and each local station 2 include an optical pulse tester (OTDR Optical Time) that measures transmission characteristics, attenuation characteristics, normal / abnormal failure determination, disconnection position, etc. of the optical fibers 3 connected between the stations. Domain Reflect meter (hereinafter abbreviated as OTDR) 4 is provided. The OTDR 4 applies the optical pulse 6 shown in FIG. 13 to one optical fiber 3 selected by the optical switch 5 and measures the backscattered light 7 with respect to the optical pulse 6. Then, from the waveform of the backscattered light 7, the transmission characteristics, attenuation characteristics, presence / absence of disconnection, disconnection position, and the like of the optical fiber 3 are measured. The measurement results are tabulated at a monitoring terminal 8 made of, for example, a personal computer (PC) provided in the central station 1 and the local station 2.

  The monitoring terminal 8 sequentially selects the optical fiber 3 connected to the OTDR 4 via the optical switch 5 and sets measurement conditions for the selected optical fiber 3 in the OTDR 4.

FIG. 13 is a measurement sequence diagram for one optical fiber 3. First, the measurement conditions are set from the monitoring terminal 8 at the measurement condition setting time T _{S, and the} above-described measurement is performed at the measurement time Tm. It transmits the measurement result to the monitoring terminal 8 at the next data transmission time T _D.

Here, the measurement condition setting time T _S and the data transmission time T _D are substantially constant for all the optical fibers 3, but the measurement time Tm is the length of the optical fiber 3 to be measured (laying distance, (Or distance span). In general, since the light intensity of the backscattered light 7 is low, the optical pulse 6 is transmitted repeatedly at a constant transmission interval T _L , for example, N = 12000 times, and the average of the obtained N backscattered light 7 is averaged. The waveform is the measurement result. Specifically, the sequentially obtained backscattered light 7 is added, for example, 10,000 times, and the digit position of the added value is moved.

Since the transmission interval T _L of the light pulses 6 the length of the optical fiber 3 corresponding to a long and time backscattered light 7 is obtained becomes long, the measurement time Tm is longer, the total time required for measurement T _A becomes longer .

The monitoring terminal 8 of each of the stations 1 and 2 that has received the measurement result of each optical fiber 3 from the OTDR 4 for each measurement required time T _A via a communication line 9 such as a communication LAN installed between the stations 1 and 2. Then, the data is transmitted to the central monitoring device 10 provided in the central office 1.

  As a result, the supervisor stationed in the central station 1 uses the central monitoring device 10 to transmit and attenuate the transmission characteristics and attenuation of each optical fiber 3 in an optical communication network in which a plurality of stations 1 and 2 are connected by the optical fiber 3. The characteristics, presence / absence of disconnection, disconnection position, etc. can be monitored.

Further, in Patent Document 1, an optical fiber measuring device installed in a backbone station of an optical fiber line network selects an optical fiber core line, controls OTDR, and performs measurement on the selected core line. In addition, a technique is disclosed in which an optical fiber measurement device is accessed from a mobile monitoring device via a communication network so that the state of the optical fiber can be remotely monitored.
JP 2000-193555 A

  However, the conventional optical fiber monitoring system shown in FIG. 11 still has the following problems to be solved.

  That is, for each of the stations 1 and 2, an OTDR 5 and a monitoring terminal 8 including, for example, a PC or the like for setting measurement conditions of each optical fiber 3 and collecting measurement results are installed in the OTDR 5. Thus, if the monitoring terminal 8 consisting of a PC or the like is installed for each station 1 and 2, the manufacturing cost of the entire optical fiber monitoring system increases. Further, in order to reduce the installation cost, the monitoring terminal 8 adopts a commercially available personal computer as it is, but the OS (operating system) incorporated in the commercially available personal computer is compared with the measurement dedicated terminal. There are concerns about reliability.

  As one method for solving such inconvenience, the monitoring terminals 8 installed in the stations 1 and 2 are removed, and a single central monitoring device 10 installed in the central station 1 is used for a communication line such as a LAN. It is conceivable to directly control the OTDR 4 of each station 1 and 2 via 9.

  However, since a single central monitoring device 10 cannot simultaneously control a plurality of OTDRs 4 via the communication line 9, the transmission characteristics, attenuation characteristics, and presence / absence of disconnection of the optical fiber 3 of the entire communication network in which the stations 1 and 2 are incorporated A great deal of time is wasted monitoring the disconnection position.

For example, in the measurement sequence of FIG. 13, the measurement condition setting time T _S = 0.1 s, the data transfer time T _D = 0.15 s, and the pulse transmission interval T _L = 0 of the optical pulse 6 corresponding to the length of the optical fiber 3 .01 s and the number of repetitions N = 120,000, the required measurement time Tm = 120 s = 2 minutes. Further, assuming that the total number of optical fibers 3 to be measured is N _P = 500, the total time T _AAL required for measurement of all the optical fibers 3 connecting the stations in the optical communication network is 1000 minutes = 16.7 hours. It becomes.

  The present invention has been made in view of such circumstances, and can eliminate the monitoring terminals arranged in each station without substantially increasing the measurement time of transmission / reception of optical pulses by OTDR to the optical fiber of each station in the communication network. An object of the present invention is to provide an optical fiber monitoring method and an optical fiber monitoring system capable of simplifying the system configuration, reducing facility costs, and improving reliability.

In order to solve the above-mentioned problems, the present invention transmits an optical pulse to each station in an optical communication network in which a plurality of stations are connected by an optical fiber to the optical fiber connected to each station according to a set measurement condition. An optical fiber tester for measuring the backscattered light, setting measurement conditions for the optical pulse tester of each station via a communication line, and collecting measurement results from each optical pulse tester A monitoring method,
The measurement conditions for the optical fiber to be monitored are set for the optical pulse tester of one station, the measurement is performed for the optical fiber to be monitored using this optical pulse tester, and the measurement is performed. And setting the measurement conditions for the optical fiber connected to the optical pulse tester or collecting the measurement results for the optical pulse tester of another station during the period An optical fiber monitoring method.

Another invention is provided in each station in an optical communication network in which a plurality of stations are connected by an optical fiber, and transmits an optical pulse to the optical fiber connected to each station according to a set measurement condition. Multiple optical pulse testers that measure backscattered light and optical pulse testers in each station are connected via a communication line, setting measurement conditions for each optical pulse tester, and each optical pulse test An optical fiber monitoring system comprising a central control unit for collecting measurement results from a vessel,
The central control unit sets the measurement conditions for the optical fiber b to be monitored for the optical pulse tester of one station, and then the optical pulse tester performs the measurement for the optical fiber to be monitored. An optical fiber monitoring system characterized in that, during a period, measurement conditions are set for an optical fiber connected to the optical pulse tester, or measurement results are collected with respect to the optical pulse tester of another station.

  In the optical fiber monitoring method and the optical fiber monitoring system configured as described above, three times of measurement condition setting, measurement, and measurement result collection (transfer) performed on each optical fiber by the OTDR disposed in each station. Of the measurement sequence consisting of, measurement condition setting and measurement result collection need to be controlled from the outside via a communication line, for example, but measurement is a measurement process of OTDR alone. This measurement time is much longer than other measurement condition settings and measurement result collection.

  Therefore, during this measurement time, the central control unit can perform measurement condition setting and measurement result collection for the OTDR of other stations, so that the idle time can be used effectively, so even with one central control unit Even if it exists, the operation rate of each OTDR can be improved and the measurement of each optical fiber can be implemented efficiently.

  Further, according to another invention, in the optical fiber monitoring system according to the invention, a plurality of optical fibers are alternatively connected to an optical pulse tester provided in each station via an optical switch. Furthermore, the central control unit has a measurement condition table for storing measurement conditions including measurement parameters in each optical pulse tester and a measurement order of a plurality of optical fibers belonging thereto, and a pulse test for setting measurement conditions next. A measuring optical pulse tester determining unit that determines the waiting time to be minimum while maintaining the measuring order of the optical fibers belonging to the same optical pulse tester.

In the optical fiber monitoring system configured as described above, a plurality of optical fibers are alternatively connected to the OTDR of each station via an optical switch. When the installation distance is different, as described above, the pulse transmission interval T _L of the optical pulse changes, and the measurement time Tm changes. When the measurement time Tm changes, since the measurement duration T _A of each optical fiber is mixed, by Tsumeawaseru under the conditions of the measurement of each optical fiber was maintained measurement sequence belonging to the same OTDR, the total measurement time Can be shortened.

  Further, according to another invention, in the optical fiber monitoring system of the invention described above, a plurality of optical fibers are alternatively connected to the optical pulse tester provided in each station via an optical switch. The central control unit further includes a measurement condition table for storing measurement conditions including measurement parameters in each optical pulse tester and a measurement order of a plurality of optical fibers to which the central control unit belongs, and one optical pulse tester for one station. Polling time calculation means for calculating a polling time for collecting measurement results after completion of the measurement of the optical fiber after setting of the measurement conditions of the optical fiber, and a processing waiting period until the measurement result collection is started A polling execution unit that polls an optical pulse tester to which an optical fiber whose current time has passed the polling time belongs, and a measurement result collection unit that collects measurement results of the optical fiber.

  In the optical fiber monitoring system configured in this way, the polling time indicating the timing at which the central control unit goes to collect the measurement results of each optical fiber for each OTDR is calculated each time. Although the measurement results of each optical fiber were collected for OTDR, the occurrence rate of the situation where the measurement results could not be collected can be reduced, and the processing efficiency of the central control unit can be improved.

  In the optical fiber monitoring system of the present invention, the monitoring terminal disposed in each station can be removed without increasing the time required to complete the measurement of all optical fibers, thereby simplifying the system configuration and reducing equipment costs. Reliability can be improved.

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

  FIG. 1 is a schematic configuration diagram of an optical communication network in which an optical fiber monitoring system to which an optical fiber monitoring method according to an embodiment of the present invention is applied is incorporated. The same parts as those in FIG. 12 are denoted by the same reference numerals.

  Each optical fiber cable 12 is laid between the stations 1 and 2 in the optical communication network including the central station 1 and the plurality of local stations 2. FIG. 2 is a schematic diagram of the central station 1, and FIG. 3 is a schematic diagram of each local station 2. As shown in FIGS. 2 and 3, each optical fiber cable 12 is used to monitor a large number of optical fibers 13 actually used for optical communication, such as 1000, and the entire optical fiber cable 12. It is composed of an optical fiber 14 called “dark fiber” that is not used for optical communication of a book.

  A large number of optical fibers 13 constituting each optical fiber cable 12 are connected to an exchange device 15 provided in the stations 1 and 2. On the other hand, one optical fiber 14 used for monitoring each optical fiber cable 12 is connected to the OTDR 4 via the optical switch 5. Since the laying distance of each optical fiber cable 12 varies according to the inter-station distance L and is not constant, the length of each optical fiber 14 that is alternatively connected to the OTDR 4 by the optical switch 5 is not constant. The optical fiber 14 used for monitoring the optical fiber cable 12 connecting the stations 1 and 2 is connected only to the OTDR 4 of one of the stations, and the other end is opened.

  As shown in FIG. 2, the OTDR 4 communicates with a central control unit 16 provided in the central station 1 via a communication line 9 such as a communication LAN laid between the stations 1 and 2. Communication IF (interface) 17, measurement condition memory 33 for storing measurement conditions for each optical fiber 14 set by the central control unit 16, and one optical fiber 14 selected by the optical switch 5, as shown in FIG. The optical pulse 6 shown in (a) is applied to measure the measurement unit 34 that measures the backscattered light 7 with respect to the optical pulse 6, and the measurement result of the measurement unit 34 is sent to the central control unit 16 of the central station 1 via the communication IF 17. And a control unit 35 that sends a selection command of the optical fiber 14 designated by the central control unit 16 of the central office 1 to the optical switch 5 of the central station 1.

  FIG. 4 is a schematic diagram showing an extracted optical fiber monitoring system incorporated in the optical communication network of FIG. A central control unit 16 provided in the central station 1 directly controls operations of the OTDRs 4 provided in the stations 1 and 2 via a communication line 9 such as a LAN. In the optical fiber monitoring system of this embodiment, n stations 1 and 2 including the central station 1 are installed. Therefore, the central control unit 16 controls n OTDRs 4 via the communication line 9. Compared with the conventional optical fiber monitoring system shown in FIG. 12, it can be understood that the monitoring terminals 8 provided in the stations 1 and 2 are removed.

  FIG. 5 is a block diagram showing a schematic configuration of the central control unit 16 constituted by an information processing apparatus such as a computer provided in the central office 1.

  In the central control unit 16, a communication interface 17 for exchanging various information via the OTDR 4 and the communication line 9 provided in the stations 1 and 2, an operation unit 18, a display unit 19, and a clock for measuring the current time t. A circuit 20 and a storage unit 21 such as an HDD (hard disk driver) are provided. In the storage unit 21, a measurement condition table 22, a fiber measurement state table 23, a data file 24, and the like are provided.

In the measurement condition table 22, as shown in FIG. 6, measurement conditions for transmission / reception of the optical pulse 6 to / from each optical fiber 14 connected to the OTDR 4 provided in each of the stations 1 and 2 via the optical switch 5 are stored. Has been. Measurement conditions for each optical fiber 14 include the pulse transmission interval T _L , the pulse width T _W , and the number of repeated transmissions of the optical pulse 6 corresponding to the laying distance (distance range) L of the optical fiber cable 12 to which the optical fiber 14 belongs. An averaging number N _A , which is the number of receptions of the backscattered light 7 equal to N, and a measurement time Tm are set.

  Note that the measurement time Tm can be calculated from other measurement conditions without being set in advance. Further, optical fiber numbers (F11, F12, F13,..., F21, F22,...) Indicating the measurement order in the OTDR 4 to which the self belongs are assigned.

  Here, the details of the measurement on the optical fiber 14 of the measurement unit 34 of the OTDR 4 in each of the stations 1 and 2 will be described. As described above, the measurement unit 34 of each OTDR 4 repeats the optical pulse 6 N times and applies it to the optical fiber 14 to be measured as shown in FIG. Back scattered light 7 shown in FIG. 7B is sequentially incident from the optical fiber 14. The measurement unit 34 of the OTDR 4 sequentially adds the waveforms of the backscattered light 7 that is sequentially incident.

Then, when the application of the N light pulses 6 is finished, the addition of the waveforms of the N backscattered light 7 is finished and divided by the average number Na equal to N, and the average of the backscattered light 7 is obtained. A waveform is obtained, and this average waveform is taken as the measurement result of the optical fiber 14. Actually, N is set to 10 ⁿ and only the decimal point position is moved. The measurement time Tm is a value obtained by multiplying the pulse transmission interval T _L by the number of transmissions N (= Na) (Tm = T _L × N).

FIG. 7C shows a measurement sequence diagram for one optical fiber 14. First, the measurement conditions are set from the central control unit 16 via the communication line 9 at the measurement condition setting time T _{S, and the} measurement is performed by applying the N optical pulses 6 described above at the measurement time Tm. The measurement results at the next data transfer time T _D, is transmitted via the communication line 9 to the central control unit 16. Incidentally, in this embodiment, when the measurement time Tm has ended, necessarily does not identify the next data transfer time T _D is started, be an optical fiber 14 even if the measuring time Tm equal, measurement there is a case where the required time T _a is changed.

  In the fiber measurement state table 23, as shown in FIG. 8, each optical fiber 14 connected to the OTDR 4 provided in each of the stations 1 and 2 via the optical switch 5 is measured in the OTDR 4 in the measurement order (F11, F12,..., F21, F22,..., Fn1, Fn2,.

  Further, a measurement waiting time Fm indicating that the measurement time Tm in each optical fiber 14 and the OTDR 4 to which the optical fiber 14 belongs is in the next measurement order and waiting for setting measurement conditions is stored. . Therefore, before starting measurement in this optical fiber monitoring system, the setting waiting flag Fr is stored for the first optical fiber 14 (F11, F21,..., Fn1) of the plurality of optical fibers 14 belonging to each OTDR4. Yes.

Further, in the fiber measurement state table 23, when the measurement time Tm for the optical fiber 14 of the own fiber is completed and the measurement result is transmitted (transferred) to the central control unit 16, the central control unit 16 relates to the optical five 14. The polling time t _P of polling to be transmitted to is stored. This polling time t _P is a time obtained by adding the measurement time Tm to the current time t of the clock circuit 20 when the set time T _S ends.

t _P = t + Tm
In the data file 24, as shown in FIG. 9, the measurement result of each optical fiber 14 connected to the OTDR 4 provided in each of the stations 1 and 2 via the optical switch 5 (average waveform of the backscattered light 7). However, the date of acquisition is attached and stored.

  In the central control unit 16 of FIG. 5, an OTDR counter 25, a measurement optical pulse tester determination unit 26, a measurement condition setting unit 27, a polling time calculation unit 28, a polling execution unit 29, and a measurement are formed on the application program. The fruit collection means 30, the setting waiting flag setting part 31, the analysis part 32, etc. are provided.

  Next, the operation of each part will be described in order. For example, the operation unit 18 formed by a keyboard, a mouse, or the like accepts various operations by a maintenance manager working at the central office 1 or an inspector of the optical fiber cable 12. For example, when measurement start is input, the OTDR counter 25 and the measurement light pulse tester determination unit 26 are activated.

  When the operation start is instructed from the operation unit 18, the OTDR counter 25 sequentially reads the number DR of each OTDR 4 in the fiber measurement state table 23 and sends it to the measurement optical pulse tester determination unit 26. The reading of the number DR of the OTDR 4 is stopped when the measurement for the first optical fiber 14 in each OTDR 4 is completed.

  The measurement optical pulse tester determination unit 26 designates the head optical fiber 14 connected to the OTDR 4 with the number DR transmitted from the OTDR counter 25 and transmits the designated optical fiber 14 to the measurement condition setting unit 27. That is, first, each head optical fiber 14 (F11, F21,..., Fn1) is determined as an optical fiber to be measured in order and sent to the measurement condition setting unit 27. Thereafter, according to the setting status of the setting waiting flag of each optical fiber 14 set in the fiber measurement state table 23, the central control unit 16 has the least waste time on the time axis at that time. The minimum optical fiber 14 is determined as the measurement optical fiber and is sent to the measurement condition setting unit 27.

  That is, the measurement optical pulse tester determination unit 26 determines the OTDR 4 to which the optical fiber 14 to be measured belongs, which has the least waste and has the minimum idle time on the time axis.

The measurement condition setting unit 27 transmits the measurement conditions (pulse transmission interval T _L , pulse width T _W , averaging number Na) of the optical fiber 14 determined by the measurement optical pulse tester determination unit 26 via the communication line 9. , The measurement condition memory 33 of the OTDR 4 to which the corresponding optical fiber 14 belongs is set. The OTDR 4 for which the measurement condition is set in the measurement condition memory 33 starts measurement for the optical fiber 14 based on the set measurement condition. When the measurement condition setting is completed, the measurement condition setting unit 27 cancels the setting wait flag for the optical fiber 14 and activates the polling time calculation unit 28.

The polling time calculation unit 28 sets the time obtained by adding the measurement time Tm of the optical fiber 14 stored in the measurement condition table 22 to the current time t read from the clock circuit 20 as the polling time t _P , and the fiber measurement state table 23. To the area of the optical fiber 14.

The polling execution unit 29 checks whether or not the polling time t _P is set in the fiber measurement state table 23. If it is set, the condition is that the current time t exceeds the polling time t _P and Then, polling for transmission of the measurement result is performed to the OTDR 4 of the optical fiber 14 in which the polling time t _{P at} which the current time t is greatly exceeded is set. When a transmittable polling result is obtained, the transmittable polling result is sent to the measurement result collecting means 30.

  The measurement result collecting means 30 transmits a transmission request for the measurement result to the OTDR 4 of the optical fiber 14 of the polling result that can be transmitted. The OTDR 4 that has received the transmission request transmits (transfers) the measurement result stored in the control unit 35 to the central control unit 16 via the communication line 9. The measurement result collecting means 30 that has received the measurement result writes this measurement result in a new area in the data file 24 together with the current time t (acquisition time) of the clock circuit 20. Further, the measurement result collecting unit 30 activates the setting waiting flag setting unit 31.

  The setting waiting flag setting unit 31 sets a setting waiting flag for the next optical fiber 14 in the same OTDR 4 of the corresponding optical fiber 14 in the fiber measurement state table 23.

  After the measurement for all the optical fibers 14 in the optical fiber monitoring system is completed, the analysis unit 32 determines the optical fiber 14 stored in the data file 24 based on an instruction from the administrator via the operation unit 18. An analysis is performed on the entire optical communication network using the measurement result, and the analysis result is displayed on the display unit 19.

  The central control unit 16 configured as described above performs measurement control on each optical fiber 14 according to the flowchart of FIG.

When the administrator inputs measurement conditions for each optical fiber 14 via the operation unit 18 (step S1), the measurement conditions are set in the measurement condition table 22 (S2). Further, the measurement time Tm and the setting waiting flag Fr are set in the fiber measurement state table 23. When a measurement start command is input from the operation unit 18 (S3), the number DR of the OTDR counter 25 is initialized (DR = 1) (S4). The measurement condition of the first optical fiber 14 of the OTDR with the number DR in the measurement condition data table 22 is read and set (downloaded) in the measurement condition memory 32 of the OTDR 4 (S5). Then, the OTDR 4 starts measurement (S6). Further, a polling time t _P (= t + Tm) obtained by adding the measurement time Tm to the current time t is calculated and set in the corresponding optical fiber 14 of the fiber measurement state table 23 (S7). Then, the setting wait flag of the optical fiber 14 is canceled.

  As described above, since the measurement start process for one optical fiber 14 is completed, when it is confirmed that the number DR of OTDR4 does not exceed the number n of OTDR4 installed (S8), the number DR of the OTDR counter 25 is updated (DR = DR + 1) (S9), the process returns to S5, and the setting process for the measurement condition of the first optical fiber 14 of the updated OTDR with the number DR is started.

When the OTDR number DR reaches the number of installed OTDRs n in S8, the measurement condition setting for the first optical fibers 14 (F11, F21,..., Fn1) of each of the n OTDRs 4 is completed. It is checked whether or not the polling time t _P is set in the measurement state table 23 (S10). If set, under the condition that the current time t exceeds the polling time t _P (S11), and the polling time t _P of the current time t has exceeded the largest is set (S12), light Polling for transmission of the measurement result to the OTDR 4 of the fiber 14 is performed (S13). When a polling result that can be transmitted is obtained (S14), the measurement result is received from the OTDR 4 (S15) and written to the data file 24 (S16).

Then, the polling time t _P of the corresponding optical fiber 14 in the fiber measurement state table 23 is cleared (S17). Further, if there is an optical fiber 14 with the next number in the same OTDR 4 of the optical fiber 14 (S18), a setting waiting flag is set for the optical fiber 14 with the next number (S19). If the optical fiber 14 of the next number does not exist in S18, the measurement for all the optical fibers 14 connected to the corresponding OTDR 4 is completed, and the process returns to S10 as it is.

If a polling result that can be transmitted is not obtained in S14, it is checked in S20 whether or not there is an optical fiber 14 in which the setting waiting flag is set in the fiber measurement state table 23. If there is, the measurement condition of the optical fiber 14 in the measurement condition table 22 is read out and set (downloaded) in the measurement condition memory 32 of the OTDR 4 (S21). Then, the OTDR 4 starts measurement (S22). Further, a polling time t _P (= t + Tm) obtained by adding the measurement time Tm to the current time t is calculated and set in the corresponding optical fiber 14 of the fiber measurement state table 23 (S7). Then, the setting wait flag of the optical fiber 14 is canceled. Thereafter, the process returns to S10.

Further, when the current time t does not exceed the polling time t _{P in} S11, the process proceeds to S20. In S20, if there is no optical fiber 14 in which the setting waiting flag is set in the fiber measurement state table 23, the measurement for all the optical fibers 14 in the optical fiber monitoring system is completed. Wait for operation.

FIG. 11 is a time chart showing the measurement operation. When measurement is started at time B ₁ , first, the measurement conditions of the first optical fibers 14 (F 11, F 21,..., Fn 1) connected to the OTDRs 4 with numbers DR = 1 to DR = n are sequentially set. The measurement is started sequentially. at time B ₂ which set the measurement conditions of the head of the optical fiber 14 of OTDR4 No. n (Fn1) is completed, the No.1 polling time t _P of the current time t has exceeded the largest is set in OTDR4 Polling is performed on the first optical fiber 14 (F11). The measurement result of the first optical fiber 14 (F11) is taken from the first OTDR4.

At time B ₃ to measure the result transfer of the optical fiber 14 (F11) has been completed, setting wait flag Fr is set to the second optical fiber 14 of the same OTDR4 (F12). At time B ₃ , transfer of the measurement result of the first optical fiber 14 (F 21) of the second OTDR 4 is started according to the polling time t _P.

However, at time B _4, at the time the measurements of the optical fiber 14 (F21) transfer has been completed, the optical fiber 14 is not present the polling time t _P which is greater than the current time t is set, The measurement condition is set for the second optical fiber 14 (F12) of the first OTDR 4 in which the setting wait flag Fr is set.

Further, at time B ₅ to set the measurement conditions for the second optical fiber 14 of the No. 1 OTDR4 (F12) has been completed, (n-1) th of OTDR4 the first optical fiber 14 (Fn-1 1 ) Is set to the polling time t _P before the current time, so polling was performed for the (n−1) th OTDR4, but measurement for the optical fiber 14 (Fn−1 1) was completed. Absent. In this case, polling is performed on the third optical fiber 14 (F31) having the next highest priority, and the measurement result is transferred.

In the optical fiber monitoring system in which the optical fiber monitoring method configured as described above is incorporated, the measurement sequence for one optical fiber 14 is transmitted from the central control unit 16 to the communication line 9 as shown in FIG. a measurement condition setting time T _S the measurement conditions are set _through, consisting of a measuring time Tm performing measurements at OTDR4, the transmission time T _D which transmits the measurement results to the central control unit 16, the measurement The communication line 9 and the central control unit 16 are not involved in the time Tm.

  Therefore, the central control unit 16 can use the measurement time Tm for setting measurement conditions for other OTDRs 4 and collecting (transferring) measurement results, so that the measurement work efficiency of each optical file 14 of the optical fiber monitoring system is greatly increased. Can be improved.

In particular, the measurement time Tm is much larger than the set time T _S and the transmission (transmission) time TD. Therefore, the measurement efficiency can be further improved by effectively using the measurement time Tm.

Furthermore, the polling time t _P indicating the timing when the central control unit 16 goes to collect the measurement results of each optical fiber 14 for each OTDR 4 is calculated when the measurement conditions are set, and is registered in the fiber measurement state table 23. Te, set for each of the optical fibers 14, each time the process of transfer (collection) is completed, by referring to the polling time t _P, so that towards the collection of measurement results. Therefore, although the central control unit 16 went to collect the measurement results of each optical fiber for each OTDR 4, it is still being measured and the occurrence rate of the situation where the measurement results could not be collected can be reduced. Processing efficiency can be improved.

In this way, by adopting the polling time t _P indicating the timing to go to collect the measurement results of each optical fiber 14, even if a plurality of optical fibers 14 having different lengths are connected to each OTDR 4, Measurement of the optical fiber 14 can be performed efficiently.

  In addition, this invention is not limited to embodiment mentioned above. In the embodiment, the end of measurement is detected by polling, but the OTDR itself may have a function of notifying the end of measurement.

The figure which shows the optical communication network incorporating the optical fiber monitoring system with which the optical fiber monitoring method of one Embodiment of this invention is applied Schematic configuration diagram of the central office of an optical communication network Schematic configuration diagram of local stations of optical communication network Schematic diagram of an optical fiber monitoring system extracted from an optical communication network Block diagram showing schematic configuration of central control unit incorporated in optical fiber monitoring system The figure which shows the memory content of the measurement condition table formed in the memory | storage part of the same central control part Optical pulse applied to optical fiber and measurement sequence diagram The figure which shows the memory content of the fiber measurement state table formed in the memory | storage part of the same central control part The figure which shows the memory content of the data file formed in the memory | storage part of the same central control part Flow chart showing optical fiber measurement control operation of the central control unit Time chart showing optical fiber measurement control operation of the central control unit Schematic diagram of a conventional optical fiber monitoring system Conventional optical fiber measurement sequence diagram

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Central station, 2 ... Local station, 4 ... OTDR, 5 ... Optical switch, 6 ... Optical pulse, 9 ... Communication line, 12 ... Optical fiber cable, 14 ... Optical fiber, 15 ... Switching apparatus, 16 ... Central control part , 18 ... operation section, 19 ... display section, 20 ... clock circuit, 21 ... storage section, 22 ... measurement condition table, 23 ... fiber measurement state table, 24 ... data file, 25 ... OTDR counter, 26 ... measurement light pulse test Measuring unit, 27 ... measurement condition setting unit, 28 ... polling time calculation unit, 29 ... polling execution unit, 30 ... measurement result collecting means, 31 ... setting wait flag setting unit, 32 ... analysis unit, 33 ... measurement condition memory, 34 ... Measurement unit, 35 ... Control unit

Claims (4)

An optical pulse (6) is applied to each of the stations in the optical communication network in which a plurality of stations (1, 2) are connected to each other by an optical fiber (14) according to a set measurement condition. An optical pulse tester (4) for transmitting and measuring backscattered light is provided, and measurement conditions are set for the optical pulse tester of each station via a communication line (9). An optical fiber monitoring method for collecting measurement results from
Setting measurement conditions for the optical fiber to be monitored for the optical pulse tester of one station, performing the measurement for the optical fiber to be monitored using the optical pulse tester, and the measurement Setting the measurement conditions for the optical fiber connected to the optical pulse tester or collecting the measurement results for the optical pulse tester of another station during the period of performing An optical fiber monitoring method. An optical pulse (6) is provided to each station in the optical communication network in which a plurality of stations (1, 2) are connected to each other by an optical fiber (14) and connected to each station according to a set measurement condition. ) To measure the backscattered light and the optical pulse tester (4) connected to the optical pulse tester of each station via a communication line (9), An optical fiber monitoring system comprising a central control unit (16) for setting measurement conditions for the optical pulse tester and collecting measurement results from the optical pulse testers,
The central control unit (16) sets measurement conditions for the optical fiber b to be monitored for the optical pulse tester of one of the stations, and then the optical pulse tester applies to the optical fiber to be monitored. During the period of the measurement, setting the measurement conditions for the optical fiber connected to the optical pulse tester or collecting the measurement results for the optical pulse tester of the other station. An optical fiber monitoring system. A plurality of optical fibers (14) are alternatively connected to the optical pulse tester (4) provided in each station via an optical switch (5),
The central control unit (16)
A measurement condition table (22) for storing measurement conditions including measurement parameters in each optical pulse tester and measurement order of the plurality of optical fibers belonging to the optical pulse tester;
Next, a measurement optical pulse tester determination unit (26) that determines the waiting time to be minimum while maintaining the measurement order of optical fibers belonging to the same optical pulse tester for the pulse tester for setting measurement conditions. And an optical fiber monitoring system according to claim 2. A plurality of optical fibers are alternatively connected to the optical pulse tester provided in each station via an optical switch,
The central control unit (16)
A measurement condition table (22) for storing measurement conditions including the measurement parameters in each optical pulse tester and the measurement order of the plurality of optical fibers belonging to the optical pulse tester;
Polling time calculation means for calculating a polling time for collecting measurement results after the measurement of the optical fiber is completed after setting of the measurement condition of the optical fiber for the optical pulse tester of the one station is completed. 28)
A polling execution unit (29) for polling an optical pulse tester to which an optical fiber whose current time has passed the polling time belongs in a processing waiting period until the start of collection of the measurement results;
3. The optical fiber monitoring system according to claim 2, further comprising measurement result collecting means (30) for collecting the measurement result of the optical fiber.

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