JP2007318415A - Optical transmission line monitoring device, optical transmission line monitoring method, and monitoring program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical transmission line monitoring device capable of accurately detecting abnormality of an optical transmission line even if an optical fiber is extended and contracted. <P>SOLUTION: In the optical transmission line monitoring device 1, a decision unit 15 detects a waveform part which is a waveform part where all light intensity values of successive waveform shapes are larger than a threshold for predetermined waveform part specification in a waveform formed based upon distances and light intensity values included in normal-time measurement information and includes at least a peak of at least one waveform. Further, the decision unit 15 detects a waveform part which corresponds to the shape of the waveform part detected from the normal-time measurement information in a waveform of measurement information to be monitored, and performs abnormality detection based upon the shapes of the two detected waveform parts without depending upon values of distances. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical transmission line monitoring device, an optical transmission line monitoring method, and a monitoring program for detecting an abnormality in an optical transmission line constituted by a PON.

  A single optical fiber cable (hereinafter referred to as an optical fiber) connected to a communication device provided in a communication station is branched by a splitter, and a PON that accommodates termination devices provided in a plurality of user homes by the branched optical fiber. A Passive Optical Network (Transmission Optical Network) type transmission line (hereinafter referred to as a PON transmission line) is known.

  Conventionally, when an abnormality such as a line failure occurs in a PON transmission line, for example, using OTDR (Optical Time Domain Reflectometers) etc. A pulse is incident, the return light based on Rayleigh scattering and reflection from the device is measured, and the measured information is compared with the information measured at normal time to detect the presence or absence of an abnormality. It was.

For example, Patent Document 1 and Patent Document 2 propose a technique in which a filter having different reflection characteristics is provided at an end point of an optical fiber by FBG (Fiber Bragg Grating), and a failure occurrence location of a transmission line is specified by a multi-wavelength monitoring light source. Has been. Further, in Patent Document 3, a filter having different reflection characteristics is used to terminate the optical fiber as in Patent Document 1 and Patent Document 2, using a wavelength router that outputs to an input port and an output destination port corresponding to the wavelength. There has been proposed a technique for providing a point and specifying a location where a transmission line failure occurs.
JP 2000-354008 A JP-A-8-201223 Japanese Patent No. 3588657

  By the way, in the optical fiber, as the distance approaches the end position of the optical fiber, the optical fiber expands and contracts due to the secular change or temperature change of the optical fiber, so that the peak of the waveform formed by the return light measured by OTDR appears. The position may change.

  However, in any of the techniques of Patent Documents 1, 2, and 3 described above, the occurrence of the expansion and contraction of the optical fiber as described above is not considered, and the position where the peak of the normal waveform measured in advance appears. If the measurement is performed on the optical fiber expanded and contracted by OTDR based on the above, there is a problem that a waveform peak does not appear at the position, and it is erroneously detected as an abnormality.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide an optical transmission line capable of accurately detecting an abnormality in the optical transmission line even when the optical fiber is stretched or contracted. A monitoring device, an optical transmission line monitoring method, and a monitoring program are provided.

  In order to solve the above problem, the present invention provides an optical transmission line for each distance of the optical transmission line obtained by analyzing the return light measured by entering a light pulse in the longitudinal direction of the optical fiber constituting the optical transmission line. Any one of the measurement information including the light intensity value is set as normal measurement information, and the normal transmission information and the measurement information in the state where the expansion and contraction of the optical fiber to be monitored are unknown are used. An optical transmission line monitoring device for detecting an abnormality, wherein all light intensity values of a continuous waveform shape in a waveform formed from the distance and the light intensity value included in the normal measurement information are predetermined. First detection means for detecting a first waveform portion including at least one waveform peak that is equal to or greater than a waveform portion specifying threshold, and among the waveforms of measurement information to be monitored, The first detection means detects Second detection means for detecting a second waveform portion corresponding to the shape of the first waveform portion, the shape of the first waveform portion detected by the first detection means, and the second An optical transmission line monitoring apparatus comprising: an anomaly detecting unit configured to detect an anomaly without depending on the value of the distance based on the shape of the second waveform portion detected by the detecting unit. is there.

  In the present invention, the light intensity indicated by the predetermined waveform portion specifying threshold value in the normal measurement information as the information for specifying the first waveform portion as the information for specifying the first waveform portion. A waveform width value of the first waveform portion obtained from a difference in distance corresponding to the value is detected, and the second detection means is for specifying the predetermined waveform portion based on the measurement information of the monitoring target. A value of a waveform width of the second waveform portion obtained from a difference in distance value corresponding to the light intensity value indicated by the threshold is detected, and the abnormality detection means is configured to detect the first waveform of the second waveform portion. When there is a shift in the distance value with respect to the portion, the shift amount for correcting the shift is based on the waveform width value of the first waveform portion and the waveform width value of the second waveform portion. Shift amount calculating means to calculate the distance value of the second waveform portion A correction means for correcting with the shift amount calculated by the shift amount calculation means; and a light intensity value at a distance that becomes a peak of the waveform of the first waveform portion of the second waveform portion corrected by the correction means; A first determination unit that calculates a difference from the light intensity value at the peak distance of the first waveform portion and determines whether the calculated difference exceeds a predetermined first abnormality detection threshold value. And a first output means for outputting that there is an abnormality when the first determination means determines that the calculated difference exceeds the first abnormality detection threshold value. .

  According to the present invention, in the invention described above, the abnormality detection unit calculates a difference between a waveform width of the first waveform portion and a waveform width of the second waveform portion, and the calculated difference is predetermined. A second determination unit that determines whether or not a second abnormality detection threshold is exceeded; and the second determination unit includes: a waveform width of the first waveform portion; a waveform width of the second waveform portion; And a second output means for outputting that there is an abnormality when it is determined that the difference exceeds the second abnormality detection threshold value.

  The present invention is characterized in that, in the above-described invention, there is provided threshold calculation means for calculating the predetermined waveform portion specifying threshold based on the normal measurement information and the monitoring target measurement information. .

  The present invention relates to measurement information including light intensity values for each distance of the optical transmission line obtained by analyzing return light measured by entering a light pulse in the longitudinal direction of the optical fiber constituting the optical transmission line. Optical transmission line monitoring that detects any abnormality of the optical transmission line based on any of the normal measurement information and the measurement information in a state where the expansion and contraction of the optical fiber to be monitored is unknown. In the method, all the light intensity values having a continuous waveform shape in the waveform formed from the distance and the light intensity value included in the normal measurement information are equal to or greater than a predetermined waveform portion specifying threshold. A step of detecting a first waveform portion that is a waveform portion including at least one waveform peak, and the first waveform detected by the first detection means in the waveform of the measurement information to be monitored The shape of the part Detecting an abnormality without depending on the distance value based on the detected second waveform portion, the detected shape of the first waveform portion, and the detected shape of the second waveform portion And an optical transmission line monitoring method characterized by comprising:

  The present invention relates to measurement information including light intensity values for each distance of the optical transmission line obtained by analyzing return light measured by entering a light pulse in the longitudinal direction of the optical fiber constituting the optical transmission line. Optical transmission line monitoring that detects any abnormality of the optical transmission line based on any of the normal measurement information and the measurement information in a state where the expansion and contraction of the optical fiber to be monitored is unknown. In the control computer of the apparatus, all the light intensity values of the continuous waveform shape in the waveform formed from the distance and the light intensity value included in the normal measurement information are equal to or greater than a predetermined waveform portion specifying threshold value. A first waveform portion that includes at least one waveform peak, and the first detection means detects the first waveform portion of the measurement information waveform to be monitored. Waveform part And detecting the second waveform portion corresponding to the shape of the first waveform portion, the detected shape of the first waveform portion, and the detected shape of the second waveform portion. A monitoring program for executing an abnormality detection step.

  According to the present invention, the optical transmission line monitoring device is capable of specifying a predetermined waveform portion in which all the light intensity values of the continuous waveform shape are within the waveform formed from the distance and the light intensity value included in the normal measurement information. A first waveform portion including at least one waveform peak that is equal to or greater than the threshold value for detection, and a second waveform corresponding to the shape of the first waveform portion in the waveform of the measurement information to be monitored. The waveform portion is detected, and abnormality detection is performed without depending on the distance value based on the shape of the first waveform portion and the shape of the second waveform portion. As a result, the waveform shape is the same even when the waveform formed from the normal measurement information and the waveform formed from the monitoring target measurement information have shifted due to the expansion and contraction of the optical fiber. Therefore, by performing detection based on the shape of the corresponding waveform, it is possible to perform accurate detection in consideration of displacement due to expansion and contraction of the optical fiber and to prevent erroneous detection due to expansion and contraction of the optical fiber. It becomes.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an internal configuration of an optical transmission line monitoring device 1 according to the present embodiment, an optical transmission line to be monitored by the optical transmission line monitoring device 1, a measuring device 50 for measuring the light intensity of the optical transmission line, and It is a schematic block diagram which shows the connection relations of the apparatus etc. which are connected to an optical transmission line.

  In FIG. 1, the optical transmission line is a PON optical transmission line composed of an optical fiber 60, a splitter 101, optical fibers 70-1 to 70-M, a splitter 110, and optical fibers 80-1 to 80-N. . Terminators used at the user's home are connected to the ends of the optical fibers 80-1 to 80-N. Further, the optical fibers 80-1 to 80-N are fiber Bragg gratings that generate peaks in a waveform formed by reflected light with respect to an optical pulse incident from a measuring device 50 described later, in the vicinity of the connection end of the termination device. FBG) optical filters are provided.

  The splitters 101 and 110 are devices that branch or combine optical signals, and are also called optical couplers. For example, in the splitter 101, the optical signals from the optical fiber 60 are sent to a plurality of optical fibers 70-1 to 70-M. The optical signals from the plurality of optical fibers 70-1 to 70 -M are multiplexed to the optical fiber 60. The number of branches in a general splitter is 4, 8, 16, 32, and it is possible to branch more by connecting the splitters in multiple stages.

  The directional coupler (optical coupler) 100 has three connection ends that are connected to an optical fiber. Each of the connection ends is connected to an optical fiber 200-1 that is connected to the splitter 101, and the optical switch 40. To the optical fiber 30-1 connected to the transmission device 90. The directional coupler 100 performs wavelength-dependent demultiplexing and multiplexing, communication light incident from the transmission device 90 through the optical fiber 30, and measurement incident from the optical switch 40 through the optical fiber 200-1. The optical pulses from the device 50 are combined and output to the optical fiber 60. In addition, when the directional coupler 100 is incident from the optical fiber 60 through the splitter 101, the reflected wave of communication light is not output to the optical fiber 200-1 but is connected to the transmission device 90. The output light of the optical pulse is not output to the optical fiber 30 but output to the optical fiber 200-1 connected to the optical switch 40.

  The optical switch 40 is connected to the measuring device 50 at one connection end, and a plurality of optical transmission lines through the optical fibers 200-1 to 200L and directional couplers connected to the respective optical fibers at the other connection ends. And any one connection end to which the optical fibers 200-1 to 200-L are connected is connected to the connection end to which the measuring apparatus 50 is connected based on the input switching instruction. FIG. 1 shows a state where the optical fiber 200-1 is selected.

  The measuring device 50 is, for example, the above-described OTDR, and an optical pulse signal is incident on the optical fiber 60 of the optical transmission line through the optical switch 40 and the optical fiber 200-1, and the return light returned by reflection from the optical transmission line is reflected. Receive light. Here, the return light refers to the reflected light at the connection points and fusion points of the optical fibers 60, 70-1 to 70-M, 80-1 to 80-N, and the end points of the optical fibers 80-1 to 80-N. Reflected light at the terminal device connected to the optical fiber, reflected light from the optical filters 60, 70-1 to 70-M, and 80-1 to 80-N. Includes backscattered light due to Rayleigh scattering. In addition, the measuring device 50 measures the light intensity value of the received return light, calculates a distance based on the light reception time, and outputs the measured light intensity value and the calculated distance as measurement information.

  The optical line monitoring device 1 receives the measurement information of the optical transmission line from the measurement device 50, stores the received measurement information, or the measurement information received from the measurement device 50 in advance, and stores it after the measurement is completed. The presence or absence of an abnormality due to a failure is detected based on certain measurement information. In the optical line monitoring device 1, the connection unit 10 is an interface connected to the measurement device 50. The operation unit 14 is connected to an input device such as a keyboard or a mouse, detects a signal output from the input device that has been operated by the user, and inputs information corresponding to the detected signal. The output unit 18 is connected to, for example, a CRT (Cathode Ray Tube) or a liquid crystal screen, displays a waveform formed by measurement information received from the measurement device 50, or generates an abnormality when an abnormality is detected. Display information on the screen.

  The measurement information DB (Data Base) 12 stores measurement information received from the measurement device 50 through the connection unit 10. The waveform analysis unit 11 reads measurement information from the measurement information DB 12, and detects a value on a distance axis where a waveform peak formed from the read measurement information exists (hereinafter also referred to as a peak position). Process. In the following description, measurement information that is selected in advance by the user as measured when the optical transmission line is normal in the measurement information stored in the measurement information DB 12 is described as normal measurement information, and is monitored. The measurement information measured by the measurement device 50 at the time of the target is described as monitoring target measurement information.

  The determination unit 15 selects a specific waveform portion including at least one peak of a waveform formed from measurement information, ie, a waveform portion specifying threshold (predetermined waveform portion specifying threshold) set by a threshold calculation unit 13 described later. Based on the threshold value for extraction, a waveform portion is extracted from a waveform formed from normal measurement information, and a waveform portion of a waveform formed from monitoring target measurement information is extracted.

  Further, the determination unit 15 determines the light intensity value at the peak position of the waveform formed by the normal measurement information and the monitoring target measurement information at the peak position based on the normal measurement information and the monitoring target measurement information. The difference in light intensity value is calculated. Further, the determination unit 15 determines whether or not the calculated difference value of the light intensity value exceeds a predetermined peak abnormality detection threshold (first abnormality detection threshold).

  The determination unit 15 also includes a waveform width value extracted from the waveform formed from the normal measurement information, and a waveform width value extracted from the waveform formed from the monitoring target measurement information. Is calculated, and it is determined whether or not the difference between the calculated waveform width values exceeds a predetermined waveform width abnormality detection threshold value (second abnormality detection threshold value).

  In addition, when the determination unit 15 determines that the peak abnormality detection threshold is exceeded in the determination based on the above-described peak abnormality detection threshold and the correction unit 17 does not perform correction, the optical fiber is expanded or contracted. In order to correct the deviation caused by the above, a shift amount calculation instruction signal is input to the shift amount calculation unit 16 to calculate the shift amount for correction. In addition, when the correction unit 17 performs correction, the determination unit 15 performs determination based on the above-described peak abnormality detection threshold again, and the determination results in a difference in light intensity value at the peak of the normal measurement information. When it is determined that the abnormality detection threshold is exceeded, an alarm notification instruction signal is input to the output unit 18 to notify the abnormality.

  The shift amount calculation unit 16 receives the shift amount calculation instruction signal input by the determination unit 15 and is based on the expansion and contraction of the optical fiber based on the normal measurement information determined by the determination unit 15 and the monitoring target measurement information. A shift amount for correcting the shift is calculated. The correction unit 17 corrects the distance value of the monitoring target measurement information based on the shift amount calculated by the shift amount calculation unit 16.

  The threshold value calculation unit 13 sets a waveform part specifying threshold value that is referred to when the waveform part is extracted by the determination unit 15 described above based on the normal measurement information and the monitoring target measurement information stored in the measurement information DB 12. calculate. Specifically, like the threshold indicated by reference numeral 500 in FIG. 6 described later, the waveform 401 of the normal measurement information and the waveform 402-2 of the monitoring target measurement information include at least one peak, and the distance direction Are calculated as waveform portion specifying threshold values so that all the light intensity values of the continuous waveform shapes are equal to or greater than the light intensity values of the waveform portion specifying threshold values, and input to the determination unit 15. Note that the waveform portion specifying threshold value is set in the determination unit 15 by the user's operation with reference to the waveform displayed on the screen by the output unit 18 in addition to using the threshold value calculating unit 13. It may be.

  Next, with reference to FIG.2 and FIG.3, the difference in the waveform formed by measurement information when the expansion and contraction of the optical fiber occurs will be described. 2 and 3, when the user operates the operation unit 14, the output unit 18 to which the waveform display instruction signal is input by the operation unit 14 reads the normal measurement information and the monitoring target measurement information from the measurement information DB 12. It is the figure which showed the state which displayed on the screen the waveform formed from each read measurement information.

  The waveform display screen 400 shown in FIG. 2 has an area for displaying two waveforms, a partial measurement information display area 301 and a total measurement information display area 300. The partial measurement information display area 301 includes a normal measurement. A reference waveform 401 formed by information and a waveform 402 formed by measurement information to be monitored are displayed. The waveform formed by the measurement information is displayed in each region with the horizontal axis representing distance and the vertical axis representing light intensity. In the total measurement information display area 300, a waveform formed from the measurement information of both the normal measurement information and the monitoring target measurement information is displayed.

  The relationship between the partial measurement information display area 301 and the total measurement information display area 300 is the information input by the operation unit 14 that has received the operation when the user operates the mouse or the like in the total measurement information display area 300. When the area frame 302 is set on the basis, the waveform of the normal measurement information and the waveform of the measurement information to be monitored included in the set area frame 302 are displayed in the partial measurement information display area 301 by the output unit 18. There is a relationship.

  FIG. 2 shows an example in which expansion / contraction due to an optical fiber is not generated, and a reference waveform 401 formed from normal measurement information at normal time and a monitoring target waveform 402 formed from monitoring target measurement information substantially overlap each other. Since the difference between the light intensity value at the peak position of the reference waveform 401 and the light intensity value of the monitoring target waveform 402 at the position is substantially zero, the difference in light intensity value does not exceed the peak abnormality detection threshold. The position of the peak of the monitoring target measurement information is not detected as an abnormality.

  FIG. 3 is a diagram illustrating an example of the case where the optical fiber contracts, and the waveform of the monitoring target waveform 402 a has a waveform peak at a shorter distance than the reference waveform 401 with respect to the reference waveform 401. At this time, for example, with respect to the reference waveform 401, the distance has a peak at a value indicated by reference numeral 350, and the peak has a light intensity value indicated by reference numeral 351. On the other hand, the monitoring target waveform 402 a is generated with the peak generation position shifted, so that the light intensity value at the distance indicated by reference numeral 350 is the value indicated by reference numeral 351. Therefore, when the difference between these light intensity values exceeds the peak abnormality detection threshold, the monitoring target measurement information is determined to be abnormal at a distance of 350. However, in this case, only the position in the distance is shifted due to the contraction of the optical fiber, and in fact, no abnormality has occurred, and thus erroneous detection has occurred.

  Here, even if the optical fiber expands and contracts, when the same measurement apparatus 50 is used and light pulses with the same interval are incident, the monitoring target waveform 402a in which the position where the peak occurs due to the expansion and contraction is shifted, and the reference waveform It is known that 401 has a characteristic that there is no difference in the shape of the waveform except that the distance is deviated by a certain amount. Therefore, a process for preventing erroneous detection due to expansion and contraction of the optical fiber in consideration of this characteristic will be described below with reference to FIGS. 4 to 6.

  FIG. 4 is a flowchart showing a process for preventing erroneous detection due to expansion and contraction of the optical fiber in the optical transmission line monitoring apparatus 1. FIG. 5 is an enlarged view of a part of the waveform displayed in the partial measurement information display area 301 of the waveform display screen 400a of FIG. 3, and FIG. 5 shows the optical transmission line monitoring device 1 of the present embodiment. It is the figure which showed an example of the shape of the waveform which can detect abnormality using it.

  First, when the user operates the input device, the operation unit 14 that has detected the operation sends an abnormality detection start instruction signal including information for specifying monitoring target measurement information to the waveform analysis unit 11 to the waveform analysis unit 11. input. When an abnormality detection start instruction is input, the waveform analysis unit 11 reads out normal measurement information and monitoring target measurement information specified by information included in the abnormality detection start instruction signal from the measurement information DB 12, and these measurement information The analysis information such as the position where the peak of the waveform formed is detected is detected, and the detected analysis information, normal measurement information, and monitoring target measurement information are input to the threshold value calculation unit 13 (step S1).

  The threshold calculation unit 13 calculates the above-described waveform portion specifying threshold based on the normal measurement information input from the waveform analysis unit 11 and the measurement information to be monitored. The threshold calculation unit 13 inputs the waveform portion specifying threshold to the determination unit 15 and inputs information indicating that the calculation of the waveform portion specifying threshold is completed to the waveform analysis unit 11 (step S2).

  The waveform analysis unit 11 to which information indicating that the calculation of the waveform portion specifying threshold has been completed is input to the determination unit 15 next, the detected analysis information, normal measurement information, and monitoring target measurement information. When receiving the input from the waveform analysis unit 11, the determination unit 15 receives the waveform portion of the reference waveform 401 formed from the normal measurement information based on the waveform portion specifying threshold and the monitoring target formed from the monitoring target measurement information The waveform portion of the waveform 402 is extracted. Then, the determination unit 15 calculates the waveform width of each extracted waveform portion.

  Specifically, as shown in FIG. 5, the intersections 701a and 701b of the light intensity value (reference numeral 500) of the waveform portion specifying threshold and the reference waveform 401 of the normal measurement information are detected, and the distance between the intersections 701a and 701b is detected. The difference between the values is calculated, and the calculated difference is defined as the waveform width (reference numeral 601). Further, the intersection point 702a and 702b between the light intensity value (reference numeral 500) of the waveform portion specifying threshold and the monitoring target waveform 402-1 of the monitoring target measurement information is detected, and the difference between the intersection points 701a and 701b is calculated and calculated. The difference is calculated as the waveform width (reference numeral 602).

  Then, the determination unit 15 determines whether or not the difference between the calculated waveform width (reference numeral 601) and the waveform width (reference numeral 602) exceeds the aforementioned waveform width abnormality detection threshold (step S3). When the determination unit 15 determines that the difference between the calculated waveform width values exceeds the waveform width abnormality detection threshold, the determination unit 15 inputs an alarm notification instruction signal to the output unit 18 to notify the abnormality, and receives the input. The unit 18 displays that an abnormality has occurred on the screen (step S4).

  A specific example of step S3 will be described with reference to FIG. FIG. 6A is a diagram showing a normal waveform obtained by measuring with the OTDR assuming an OTDR capable of increasing the accuracy of the optical pulse width, and FIG. FIG. 5 is a diagram showing a normal waveform, that is, a reference waveform 401, when the optical pulse width is measured with an optical pulse width of an accuracy used in normal measurement.

 In the reference waveform 401 in FIG. 6 (a '), the accuracy of the optical pulse width is rougher than that in FIG. 5 (a), and thus two peaks that exist originally are expressed as one peak. Such a phenomenon occurs when a facility that causes a peak due to reflection exists at a close distance. In this state, an abnormality occurs in the equipment corresponding to the first peak in FIG. 6 (a), and the object to be monitored as shown in FIG. Waveform 402-2 is obtained.

 The monitoring target waveform 402-2 is a waveform corresponding to the second waveform in FIG. 6A, and the reference waveform 401 in FIG. 6A ′ and the monitoring target waveform 402-2 in FIG. 6B. Although the position where the peak occurs is slightly different, the difference is extremely small, and the difference in the light intensity value at the peak is also very small.

 However, according to the optical transmission line monitoring apparatus 1 of the present embodiment described above, it is possible to detect the presence / absence of an abnormality with the waveform width even when the waveform as shown in FIG. 6B is obtained. It becomes. Specifically, when the light intensity value indicated by reference numeral 500 is set as the threshold value for specifying the waveform portion, the respective waveform widths become the sizes indicated by reference numerals 611 and 612, and the difference between these magnitudes. If a threshold value for detecting a waveform width abnormality having a smaller value is set, the waveform shown in FIG. 6B can be detected as being abnormal.

  Next, when the determination unit 15 determines in step S3 that the difference between the calculated waveform width values is equal to or smaller than the waveform width abnormality detection threshold, the light intensity at the position where the peak of the partial waveform of the reference waveform 401 exists. The difference between the value and the light intensity value of the monitoring target waveform 402 at the position where the peak exists is calculated, and it is determined whether or not the calculated difference exceeds the peak abnormality detection threshold (step S5). If the calculated difference does not exceed the peak abnormality detection threshold, the determination unit 15 determines that the difference is normal, outputs a determination result indicating normality, and ends the process (step S6).

  On the other hand, when the determination unit 15 determines that the calculated difference exceeds the peak abnormality detection threshold, the determination unit 15 does not immediately determine that an abnormality has occurred, and the determination unit 15 corrects the deviation due to the expansion and contraction of the optical fiber. It is determined whether or not it has been corrected by the unit 17 (step S7). When the determination unit 15 determines that the shift due to the expansion / contraction of the optical fiber is not corrected by the correction unit 17, the shift amount calculation instruction signal and the calculation are performed in order to cause the shift amount calculation unit 16 to calculate the shift amount for correction. Information about the waveform width of the normal measurement information and the waveform width of the monitoring target measurement information is input to the shift amount calculation unit 16. The shift amount calculation unit 16 calculates and calculates the difference between the positions of the distance axes at the intersection point 702a that is the starting point of the waveform width 602 of the monitoring target waveform 402-1 and the intersection point 701a that is the starting point of the waveform width 601 of the reference waveform 401. The difference obtained is set as the shift amount (step S9).

  The shift amount calculation unit 16 inputs the calculated shift amount to the correction unit 17, and the correction unit 17 corrects the distance of the monitoring target waveform 402-1 based on the input shift amount (step S10). When the correction is performed by the correction unit 17, the determination unit 15 performs the process of step S5 again. In the process of step S5, the determination unit 15 determines whether or not the difference in the light intensity value at the peak exceeds the peak abnormality detection threshold based on the reference waveform 401 and the corrected monitoring target waveform 402-1. If it is determined to be normal, a normal determination result is output and the process is terminated (step S6). On the other hand, if the determination unit 15 determines that the calculated difference exceeds the peak abnormality detection threshold, the determination unit 15 determines whether the measurement information to be monitored has already been corrected by the correction unit 17 (Step S15). S7). At this time, since correction is once performed by the correction unit 17, an alarm notification instruction signal is input to the output unit 18 to notify the abnormality, and the output unit 18 that has received the input has detected that an abnormality has occurred on the screen. Is displayed (step S8).

  With the configuration of the above-described embodiment, even when the expansion / contraction due to the optical fiber has occurred, it is possible to correct the deviation in which the peak due to the expansion / contraction occurs. Therefore, an abnormality in the optical fiber can be correctly detected based on the light intensity value, and erroneous detection can be prevented.

  In addition, the shift to correct the shift due to the expansion and contraction of the optical fiber by comparing the width of the specific waveform portion obtained from the waveform at normal time and the width of the specific waveform portion obtained from the waveform at the time of monitoring The amount can be calculated and corrected, and it is possible to accurately detect whether or not an abnormality has occurred by comparing the light intensity value at the position where the peak of the waveform at the normal time occurs.

  In addition, since the waveform width is compared, when two facilities exist at a close distance, when one waveform is measured as a peak, one facility is abnormally generated, and the waveform width is reduced. Even if it becomes smaller, it becomes possible to detect abnormality.

  In addition, the threshold value for specifying the waveform portion can be calculated based on the normal measurement information and the monitoring target measurement information. For example, when detecting the presence or absence of abnormality in a large amount of monitoring target measurement information, monitoring is performed. It becomes possible to reduce the work amount of the worker.

  Note that the measurement information to be monitored is stored in the measurement information DB 12 in advance in the above-described embodiment, but the present invention is not limited to this, and the measurement information received from the measurement device 50 through the connection unit 10. May be used as monitoring target measurement information as it is.

  In the above embodiment, whether or not the shift is caused by the expansion / contraction of the optical fiber is determined based on the width of the waveform. Any configuration may be used as long as it uses characteristics that do not change, and a configuration that compares the entire waveform shapes may be used.

  In the above embodiment, the PON type optical transmission line has been described as an example of the optical transmission line, but the present invention is not limited to this, and can be applied to a star-type optical transmission line or the like. is there.

  The first detection unit and the second detection unit described in the present invention correspond to the waveform analysis unit 11, and the shift amount calculation unit described in the present invention corresponds to the shift amount calculation unit 16, and a correction unit. Corresponds to the correction unit 17, the first determination unit and the second determination unit correspond to the determination unit 15, the first output unit and the second output unit correspond to the output unit 18, and the threshold value The calculation means corresponds to the threshold value calculation unit 13.

  The optical transmission line monitoring apparatus 1 described above has a computer system inside. The above-described processing for calculating the width of the waveform, the processing for correcting the expansion / contraction of the optical fiber, and the processing for detecting the abnormality are stored in a computer-readable recording medium in the form of a program. By executing this, the above processing is performed. Here, the computer-readable recording medium means a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like. Alternatively, the computer program may be distributed to the computer via a communication line, and the computer that has received the distribution may execute the program.

It is a block diagram which shows the connection relation of the optical transmission line monitoring apparatus in this embodiment, and the optical transmission line connected to the said apparatus. It is the figure which showed the example of the waveform formed from the measurement information in the same embodiment. It is the figure which showed the example of the waveform when there exists expansion-contraction of the optical fiber in the embodiment. It is the flowchart which showed the process of the optical transmission line monitoring apparatus in the embodiment. It is a figure for demonstrating the calculation means of the waveform width in the same embodiment. It is a figure for demonstrating an example of abnormality detection when the peak in the embodiment exists closely.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Connection part, 11 Waveform analysis part, 12 Measurement information DB, 13 Threshold calculation part, 14 Operation part, 15 Judgment part, 16 Shift amount calculation part, 17 Correction part, 18 Output part, 30 Optical fiber, 60 Optical fiber, 70 -1 to 70-M optical fiber, 80-1 to 80-N optical fiber, 40 optical switch, 50 measuring device, 90 transmission device

Claims (6)

The above-mentioned obtained by analyzing the return light measured by entering a light pulse in the longitudinal direction of the optical fibers (60, 70-1 to 70-M, 80-1 to 80-N) constituting the optical transmission line Any of the measurement information including the light intensity value for each distance of the optical transmission line is used as normal measurement information, and the normal measurement information and the measurement information when the expansion and contraction of the optical fiber to be monitored are unknown. An optical transmission line monitoring device (1) for detecting an abnormality of the optical transmission line based on:
A waveform portion in which all the light intensity values of a continuous waveform shape in the waveform formed from the distance and the light intensity value included in the normal measurement information are equal to or greater than a predetermined waveform portion specifying threshold value. First detection means (11) for detecting a first waveform portion including at least one waveform peak;
Second detection means (11) for detecting a second waveform portion corresponding to the shape of the first waveform portion detected by the first detection means in the waveform of the measurement information to be monitored;
Based on the shape of the first waveform portion detected by the first detection means and the shape of the second waveform portion detected by the second detection means, without depending on the value of the distance. An anomaly detecting means (15, 16, 17, 18) for detecting an anomaly;
An optical transmission line monitoring device comprising: The first detection means includes
As the information for specifying the first waveform portion, the first waveform portion obtained from the difference in distance value corresponding to the light intensity value indicated by the predetermined waveform portion specifying threshold in the normal measurement information. Detect the value of the waveform width,
The second detection means includes
Detecting the value of the waveform width of the second waveform portion obtained from the difference in the distance value corresponding to the light intensity value indicated by the predetermined threshold value for specifying the waveform portion in the measurement information of the monitoring target;
The abnormality detection means includes
When there is a shift in the distance value of the second waveform portion with respect to the first waveform portion, the shift amount for correcting the shift is set to the value of the waveform width of the first waveform portion and the first waveform portion. Shift amount calculating means (16) for calculating based on the value of the waveform width of the waveform portion of 2,
Correction means (17) for correcting the distance value of the second waveform portion with the shift amount calculated by the shift amount calculation means;
The light intensity value at the distance that becomes the peak of the waveform of the first waveform part of the second waveform part corrected by the correction means, and the light intensity value at the distance that becomes the peak of the first waveform part A first determination means (15) for determining whether the calculated difference exceeds a predetermined first abnormality detection threshold;
First output means (18) for outputting that there is an abnormality when the first determination means determines that the calculated difference exceeds the first abnormality detection threshold;
The optical transmission line monitoring apparatus according to claim 1, further comprising: The abnormality detection means includes
Calculating a difference between the waveform width of the first waveform portion and the waveform width of the second waveform portion, and determining whether the calculated difference exceeds a predetermined second abnormality detection threshold value; Determining means (15),
There is an abnormality when the second determination means determines that the difference between the waveform width of the first waveform portion and the waveform width of the second waveform portion exceeds the second abnormality detection threshold value. The optical transmission line monitoring apparatus according to claim 1, further comprising: a second output unit (18) that outputs as: Threshold calculating means (13) for calculating the predetermined waveform portion specifying threshold based on the normal measurement information and the monitoring target measurement information
The optical transmission line monitoring apparatus according to any one of claims 1 to 3, further comprising: One of the measurement information including the light intensity value for each distance of the optical transmission line obtained by analyzing the return light measured by entering the optical pulse in the longitudinal direction of the optical fiber constituting the optical transmission line is normal. An optical transmission line monitoring method for detecting abnormality of the optical transmission line based on the normal measurement information and measurement information in a state where expansion and contraction of the optical fiber to be monitored is unknown. ,
A waveform portion in which all the light intensity values of a continuous waveform shape in the waveform formed from the distance and the light intensity value included in the normal measurement information are equal to or greater than a predetermined waveform portion specifying threshold value. Detecting a first waveform portion including at least one waveform peak;
Detecting a second waveform portion corresponding to the shape of the first waveform portion detected by the first detection means in the waveform of the measurement information to be monitored;
Performing abnormality detection without depending on the value of the distance based on the detected shape of the first waveform portion and the detected shape of the second waveform portion;
An optical transmission line monitoring method comprising: One of the measurement information including the light intensity value for each distance of the optical transmission line obtained by analyzing the return light measured by entering the optical pulse in the longitudinal direction of the optical fiber constituting the optical transmission line is normal. A control computer for an optical transmission line monitoring device that detects abnormality of the optical transmission line based on the normal measurement information and measurement information when the expansion and contraction of the optical fiber to be monitored is unknown In addition,
A waveform portion in which all the light intensity values of a continuous waveform shape in the waveform formed from the distance and the light intensity value included in the normal measurement information are equal to or greater than a predetermined waveform portion specifying threshold value. Detecting a first waveform portion including at least one waveform peak;
Detecting a second waveform portion corresponding to the shape of the first waveform portion detected by the first detection means in the waveform of the measurement information to be monitored;
Performing abnormality detection without depending on the value of the distance based on the detected shape of the first waveform portion and the detected shape of the second waveform portion;
Monitoring program to execute.

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