JP4864752B2 - Optical transmission line monitoring apparatus, optical transmission line monitoring method, and monitoring program - Google Patents

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 aging or temperature change of the optical fiber. 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 apparatus for detecting an abnormality, wherein the first waveform portion includes a peak of at least one waveform among waveforms formed from the distance and the light intensity value included in the normal measurement information The first detection means for detecting the first waveform portion corresponding to the first waveform portion in the waveform of the measurement information to be monitored within a predetermined correction range including the peak of the first waveform portion. Waveform part of 2 Second detecting means for detecting a first waveform portion, the second detection means on the basis of the second waveform portion detected abnormal detection Te waveform odor of measurement information of the monitoring target Bei example an abnormality detection means for performing the first detection means, as the first information identifying a waveform portion of, detecting the value of the distance of the peak of the first waveform portion, the second The detection means detects a peak distance value of the second waveform portion within the correction range in the measurement information of the monitoring target, and the abnormality detection means detects the first waveform of the second waveform portion. A shift amount for calculating a shift amount for correcting a shift in the distance value with respect to a portion based on a peak distance value of the first waveform portion and a peak distance value of the second waveform portion The distance between the calculating means and the second waveform portion is calculated as It is determined whether there is an abnormality by comparing the correction means for correcting with the shift amount calculated by the correction amount calculation means, the second waveform portion corrected by the correction means, and the first waveform portion. An optical transmission line monitoring apparatus comprising: a first determination unit configured to perform output; and a first output unit configured to output an abnormality when the first determination unit determines that there is an abnormality. is there.

  According to the present invention, in the invention described above, the first detection unit detects a peak distance value of the first waveform portion as information specifying the first waveform portion, and the second Detecting means detects a peak distance value of the second waveform portion within the correction range in the measurement information to be monitored, and the abnormality detecting means detects the first waveform portion of the second waveform portion. A shift amount for correcting a shift of the distance value with respect to the waveform portion is calculated based on the peak distance value of the first waveform portion and the peak distance value of the second waveform portion. An amount calculating means; a correcting means for correcting a distance value of the second waveform portion by a shift amount calculated by the shift amount calculating means; the second waveform portion corrected by the correcting means; By comparing with the waveform part of 1 A first determination means for determining whether or not normal and a first output means for outputting an abnormality when the first determination means is determined to be abnormal are provided. .

  According to the present invention, in the invention described above, the distance value of the second waveform portion corresponding to the first waveform portion in the waveform of the measurement information to be monitored is the first value due to the expansion and contraction of the optical fiber. And a correction range calculation means for calculating a shift amount predicted value from the distance value of one waveform portion as the correction range.

  According to the present invention, in the above-described invention, the distance value of the second waveform portion corresponding to the first waveform portion in the waveform of the measurement information to be monitored is the expansion / contraction of the optical fiber. Storage means for storing the correction range preset by the user as a shift amount predicted value from the distance value of the first waveform portion is provided.

  According to the present invention, in the above-described invention, the second detection unit corresponds to the first waveform portion detected by the first detection unit in the waveform of the measurement information to be monitored. When a plurality of two waveform portions are detected within the correction range, the waveform portion having the peak closest to the peak of the first waveform portion is detected as the second waveform portion.

  According to the present invention, in the above-described invention, the measurement information storage unit corresponds to a reference priority number indicating a priority order using the plurality of first waveform portions detected by the first detection unit as a reference waveform. The shift amount calculating means stores a shift amount for correcting a shift in the distance value with respect to the reference waveform of the second waveform portion, and a peak distance value of the reference waveform. When calculating the reference shift amount based on the peak distance value of the waveform portion 3, the third waveform portion corresponding to the reference waveform having the reference priority number N (N is an integer starting from 1) is If not within the correction range, a shift amount for correcting a shift in the distance value is calculated based on a third waveform portion corresponding to the reference waveform whose reference priority number is N + 1. .

Further, the present invention provides a measurement including a light intensity value 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. Optical transmission for detecting abnormality of the optical transmission line based on any of the information as normal measurement information and based on the normal measurement information and measurement information in a state in which expansion and contraction of the optical fiber to be monitored is unknown A line monitoring method, wherein a first waveform portion including a peak of at least one waveform is detected from waveforms formed from the distance and the light intensity value included in the normal measurement information . And detecting a second waveform portion corresponding to the first waveform portion in the waveform of the measurement information to be monitored within a predetermined correction range including the peak of the first waveform portion. the second discard And flop, Te the said first waveform portion detected in the first step, on the basis of the second waveform portion detected in said second step, the waveform smell of measurement information of the monitoring target look including an abnormality detecting step of performing abnormality detection, the first step, as the first information identifying a waveform portion of, detecting the value of the distance of the peak of the first waveform portion, the second Step 2 detects a peak distance value of the second waveform portion within the correction range in the measurement information to be monitored, and the abnormality detection step includes the first waveform portion of the first waveform portion. A shift amount for correcting a shift of the distance value with respect to the waveform portion is calculated based on the peak distance value of the first waveform portion and the peak distance value of the second waveform portion. A quantity calculating step; The correction step of correcting the distance value of the second waveform portion with the shift amount calculated in the shift amount calculation step, the second waveform portion corrected in the correction step, and the first waveform portion A first determination step for determining whether or not there is an abnormality, and a first output step for outputting that there is an abnormality when the first determination step is determined to be abnormal. It is the optical transmission line monitoring method characterized by including.

Further, the present invention provides a measurement including a light intensity value 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. Optical transmission for detecting abnormality of the optical transmission line based on any of the information as normal measurement information and based on the normal measurement information and measurement information in a state in which expansion and contraction of the optical fiber to be monitored is unknown The computer of the line monitoring apparatus detects the first waveform portion including a peak of at least one waveform among the waveforms formed from the distance and the light intensity value included in the normal measurement information . As information specifying one waveform portion, a first step performed by detecting a peak distance value of the first waveform portion, and within a predetermined correction range including the peak of the first waveform portion , In the waveform of the measurement information of the serial monitored, the detection of the second waveform portion corresponding to the first waveform portion, the peak of the second waveform portion within the correction range in the measured information of the monitoring target Based on the second step performed by detecting the distance value, the first waveform portion detected in the first step, and the second waveform portion detected in the second step. Then, in the waveform of the measurement information to be monitored, the shift amount for correcting the shift of the distance value with respect to the first waveform portion of the second waveform portion is the peak amount of the first waveform portion. Based on the distance value and the peak distance value of the second waveform portion, the distance value of the second waveform portion is corrected by the shift amount, and the corrected second waveform Comparing the portion with the first waveform portion , It is determined whether abnormal or not, when it is determined that the abnormality is a monitoring program for executing a step of outputting as being abnormal.

As described above, according to the present invention, the optical transmission line monitoring apparatus has all the light intensity values of a continuous waveform among the waveforms formed from the distance and the light intensity value included in the normal measurement information. A first waveform portion that is a waveform portion that is equal to or greater than a predetermined waveform portion specifying threshold and includes at least one waveform peak is detected. In the correction range indicating the range including the second waveform portion corresponding to the first waveform portion and the first waveform portion, it corresponds to the first waveform portion in the waveform of the measurement information to be monitored. The second waveform portion is detected, and abnormality detection is performed based on the first waveform portion and the second waveform portion without depending on the expansion and contraction of the optical fiber. As a result, when the waveform portion disappears due to a shift in the waveform position due to a drop in the reflection level or disconnection, another waveform portion is searched endlessly, and a waveform having no corresponding relationship with the first waveform portion is searched for in the first waveform portion. It is possible to prevent erroneous detection as the second waveform corresponding to the waveform portion.
Further, in consideration of the characteristics of the optical transmission line, the amount of deviation of the second waveform portion from the first waveform portion is treated as the amount of deviation from any one of the first waveform portions as a reference shift amount. As a result, it is possible to significantly reduce the calculation cost compared to the case of calculating the shift amount for all the waveform portions. Further, even if the third waveform portion corresponding to one first waveform portion cannot be detected due to construction or disconnection by using a plurality of first waveform portions as reference waveforms, It is possible to automatically calculate a reference shift amount from another reference waveform, and when there is an abnormality in one waveform portion, it is possible to prevent other normal waveforms from being detected as abnormal. Become.
As described above, even if there is a shift in the distance axis between the waveform formed from the normal measurement information and the waveform formed from the monitoring target measurement information due to the expansion and contraction of the optical fiber, the waveform Therefore, by performing detection based on the corresponding waveform, it is possible to perform accurate detection taking into account the displacement due to the expansion and contraction of the optical fiber and to prevent erroneous detection due to the expansion and contraction of the optical fiber. It becomes.

  Next, an embodiment 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. . The optical fibers 80-1 to 80-N are connected to ONUs (Optical Network Units) 120-1 to 120-N, which are termination devices used at the user's home. Further, the optical fibers 80-1 to 80-N have peaks in the waveform formed by the reflected light with respect to the optical pulse incident from the measuring device 50 described later, in the vicinity of the connection ends of the ONUs 120-1 to 120-N. An optical filter using a fiber Bragg grating (FBG) is provided.
Further, the optical fiber lengths from the measuring device 50 to the ONUs 120-1 to 120-N that are the terminating devices are designed in advance so as to be different optical fiber lengths during the construction of the optical fiber. Therefore, the peak generated in the waveform formed by the reflected light occurs at a different position for each terminal device. Note that the return light received by the measurement device 50 includes reflected light from all terminal devices connected to the measurement device 50.

  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 the optical fiber 60 that is connected to the splitter 101 and is connected to the optical switch 40. Connected to the optical fiber 200-1 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 splitter 101 through the optical fiber 60, the reflected wave of communication light is not output to the optical fiber 200-1 but is connected to the transmission fiber 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, an OTDR (Optical Time Domain Reflectometer), which enters an optical pulse signal into the optical fiber 60 of the optical transmission line through the optical switch 40 and the optical fiber 200-1, and returns by reflection from the optical transmission line. The return light that is the reflected light in the ONUs 120-1 to 120-N is received. 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 transmission line monitoring device 1 receives the measurement information of the optical transmission line from the measurement device 50, stores the received measurement information or normal measurement information in advance, and stores the measurement information stored after the measurement is completed. Based on the above, the presence or absence of an abnormality due to a failure is detected. In the optical transmission 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 waveform analysis unit 11 performs waveform analysis processing such as detection of a value (hereinafter also referred to as a peak position) on a distance axis where a waveform peak formed from measurement information read from the measurement information DB 12 exists. Further, the waveform analysis unit 11 writes the peak position detected by the waveform analysis process or the like as peak information in the measurement information DB 12 in association with the measurement point.
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.

Further, the waveform peak analysis by the waveform analysis unit 11 is based on the normal measurement information based on the threshold value on the light intensity axis for extracting a specific waveform portion including at least one peak of the waveform formed from the measurement information. A waveform portion is extracted from a waveform formed from (hereinafter also referred to as a normal measurement waveform).
This threshold value is a value set based on statistics based on past measurement results, and may be set in advance by the user. For example, the threshold value may be a value obtained by multiplying the maximum light intensity value of the measurement information by a fixed rate. It may be set as a value that varies correspondingly, or may be set in the waveform analysis unit 11 by a user operation with reference to the waveform displayed on the screen by the output unit 18.

Here, the peak position is calculated by, for example, differentiating the waveform for each sampling point in the waveform formed from the sampled measurement information and calculating the slope, and the slope changes from a positive value to a negative value. The position is obtained as the peak position. Note that the position on the distance axis of the point where the maximum light intensity value is measured within the range that continuously exceeds the above threshold may be used as the peak position, and any method that can obtain the peak position is acceptable. You may ask for it.
The measurement information DB (Data Base) 12 is normal measurement information that is measurement information received from the measurement device 50 via the connection unit 10, monitoring target measurement information, and normal measurement information input from the waveform analysis unit 11. And normal-time peak information corresponding to. As the normal peak information, as shown in FIG. 2, the measurement information DB 12 includes a reference priority number, a distance from the measurement device 50 to the measurement point, an initial peak position of a waveform due to reflected light from the measurement point, and a correction. The area width is stored as a table corresponding to the measurement point name. The reference priority number is determined in order of the measurement points at which the waveform is easy to detect. For example, the reference priority number may be determined by the user based on statistics based on past measurement results, or the maximum distance for each measurement point may be determined. The waveform analysis unit 11 may determine the light intensity, the half width of the peak at each measurement point, and the like.

  The correction area width is a range in which the peak position can be shifted due to expansion and contraction of the optical fiber due to temperature change, construction, or the like, that is, a width of a correction range (hereinafter also referred to as a correction area). This is a predetermined width determined by the user. Further, the correction area width may be calculated by the waveform analysis unit 11 by multiplying, for example, the distance of the optical fiber from the measuring device 50 to the ONUs 120-1 to 120-N and the expansion / contraction rate due to the temperature change of the optical fiber. good.

The shift amount calculation unit 16 corrects the shift due to the expansion and contraction of the optical fiber based on the peak information of the monitoring target measurement information input from the waveform analysis unit 11 and the normal time peak information read from the measurement information DB 12. Is calculated. Note that the waveform corresponding to the normal measurement waveform is a waveform formed from monitoring target measurement information existing in the correction region for each measurement point (hereinafter also referred to as a monitoring target measurement waveform). Note that the correction area is shown in FIG. 4 in a range having the correction area end 701-1 and the correction area end 701-2 as the area ends before and after the initial peak distance 801.
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 to obtain corrected monitoring target measurement information.

  The determination unit 15 compares the peak of the waveform formed from the corrected monitoring target measurement information (hereinafter also referred to as a corrected monitoring measurement waveform) with the peak of the normal measurement waveform, and determines whether the peak due to the corrected monitoring target measurement waveform is normal. Determine whether or not.

  Next, with reference to FIG.3 and FIG.4, the difference in the waveform formed by measurement information when the expansion and contraction of the optical fiber occurs will be described. 3 and 4, 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. 3 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 normal measurement waveform 401 formed by information and a monitoring target waveform 402 formed by monitoring target measurement information are displayed. The waveform formed by the monitoring target 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 based on information input by the operation unit 14 that has received the operation when the user operates a mouse or the like in the total measurement information display area 300. When the region frame 302 is set, the waveform of the normal measurement information and the waveform of the monitoring target measurement information included in the set region frame 302 are displayed on the partial measurement information display region 301 by the output unit 18. There is.

  FIG. 3 shows an example in which expansion and contraction due to an optical fiber has not occurred. A normal measurement waveform 401 formed from normal measurement information at normal time and a monitoring target waveform 402 formed from monitoring target measurement information are shown in FIG. Since the difference between the light intensity value at the peak position of the normal measurement waveform 401 and the light intensity value of the monitoring target waveform 402 at the position is substantially zero, the difference between the light intensity values is the peak abnormality detection threshold value. Therefore, the peak position of the monitoring target measurement information is not detected as abnormal.

FIG. 4 is a diagram showing an example of the case where the optical fiber is stretched. In contrast to the normal measurement waveform 401, the monitored waveform 402a has a waveform peak at a longer distance than the normal measurement waveform 401. ing.
For example, in the normal measurement waveform 401, the distance becomes a peak at a value indicated by an initial peak distance 801, and the peak has a light intensity value indicated by reference numeral 851. On the other hand, the monitoring target waveform 402a is generated with the peak generation position shifted, so the light intensity value on the distance axis indicated by the initial peak distance 801 is the value indicated by reference numeral 852a. 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 the initial peak distance 801. However, in this case, only the position on the distance axis is shifted due to the extension of the optical fiber, and no abnormality has actually occurred, so that an erroneous detection has occurred.

Here, even if the expansion and contraction of the optical fiber occurs, when light pulses having the same interval are incident using the same measuring device 50, the monitoring target waveform 402a in which the position where the peak is generated is shifted due to the expansion and contraction and the normal time. It is known that the measured waveform 401 has a characteristic that there is no difference in waveform other than a certain amount of distance. Therefore, with reference to FIGS. 5 to 7, the process for preventing erroneous detection due to the expansion and contraction of the optical fiber in consideration of this characteristic will be described below by two processes: a preliminary preparation process and an abnormality detection process. To do.
FIG. 5 is a flowchart showing processing for preventing erroneous detection due to expansion and contraction of the optical fiber in the optical transmission line monitoring apparatus 1. FIG. 6 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. 4, and FIG. 6 shows the optical transmission line monitoring device 1 of the present embodiment. It is the figure which showed an example of the waveform which can detect abnormality using it.

<Preliminary preparation process>
First, a preparation process in which measurement information that is a normal value in advance is recorded in the measurement information DB 12 will be described.
When the user operates the operation unit 14, an initial measurement start command signal for performing an initial measurement is transmitted to the measurement apparatus 50 via the connection unit 10. When the measurement apparatus 50 receives the initial measurement start command signal, the 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 ONU 120-1 returns by reflection from the optical transmission line. The return light that is the reflected light at ˜120-N is received. The measuring device 50 measures the light intensity value of the received return light, calculates a distance based on the light receiving time, and sends the measured light intensity value and the calculated distance to the optical transmission line monitoring device 1 as normal measurement information. Transmit (step S1).

When the connection unit 10 receives the normal measurement information, the connection unit 10 outputs the received normal measurement information to the waveform analysis unit 11. The waveform analysis unit 11 detects analysis information such as the position where the peak of the received normal measurement waveform occurs, and causes the output unit 18 to display the analysis information. The waveform analysis unit 11 operates the operation unit 14 by the user, and a peak at normal time in which a waveform peak based on analysis information to be selected as one or a plurality of references is associated with a reference priority number indicating the priority order of the peaks. The information, the detected analysis information, and the normal measurement information are written in the measurement information DB 12 (step S2).
Here, the normal peak information includes the reference priority number, the measurement point name, the distance between the measurement points, the initial peak position distance analyzed by the waveform analysis unit 11, and the correction region width indicating the range of the correction region. It is the information which consists of. 4, the absolute value of the value obtained by subtracting the value on the distance axis of the correction area end 701-1 and the value on the distance axis of the correction area end 701-2 in FIG. 4 is equal to the correction area width. Thus, the distance between the two correction area ends is determined.

<Abnormality detection process>
Next, the abnormality detection process will be described. By the same operation as step S1, the measuring device 50 receives the light pulse signal at every predetermined period determined by the user, and receives the reflected light from the ONUs 120-1 to 120-N. The measurement device 50 transmits the light intensity value measured from the received return light and the distance calculated based on the light reception time to the optical transmission line monitoring device 1 as monitoring target measurement information. In the optical transmission line monitoring device 1, the connection unit 10 writes the received monitoring target measurement information in the measurement information DB 12 (step S3). As described above, it is assumed that the measurement information DB 12 is updated as needed by writing the monitoring target measurement information transmitted from the measurement device 50 at any time to the measurement information DB 12.

When the user operates the operation unit 14, an abnormality detection start command signal for performing abnormality detection is output to the waveform analysis unit 11 (step S4).
When the abnormality detection start command signal is input, the waveform analysis unit 11 receives the normal measurement information, the normal peak information, and the monitoring target measurement information specified by the information included in the abnormality detection start instruction signal from the measurement information DB 12. And read. The waveform analyzer 11 detects analysis information such as the position where the peak of the monitoring target measurement waveform occurs. The waveform analysis unit 11 outputs normal peak information, monitoring target analysis information, and monitoring target measurement information to the shift amount calculation unit 16.
The shift amount calculation unit 16 extracts the measurement point with the youngest reference priority number from the normal peak information that has been input, and corresponds to the correction region set at this measurement point, and the monitoring target peak from the monitoring target analysis information. Is extracted (step S5).
When the monitoring target peak is not detected from within the correction area at the measurement point that is to be used as the normal measurement waveform due to a decrease in the reflection level or disconnection, the shift amount calculation unit 16 adds 1 to the reference priority number. Then, step S5 is repeated until the monitoring target peak is detected from the correction region.

The shift amount calculation unit 16 calculates the shift amount 601 shown in FIG. 6, which is a shift amount indicating a deviation from the initial peak position, and outputs the shift amount 601 and the monitoring target measurement information to the correction unit 17 (step S6). ).
The measured waveform has the characteristic that there is no difference in waveform except for a certain distance, even if there is a cable change due to temperature changes or construction. In consideration of this characteristic, the shift amount calculated in step S6 indicating the shift between the monitoring target peak and the initial peak position is used as a reference value for correcting the shift of all other measurement points, and the monitoring target waveform is used. 402 can be corrected. This has the effect that accurate abnormality detection can be performed regardless of cable expansion and contraction.

A method for calculating the shift amount 601 in step S6 will be specifically described with reference to FIG.
The shift amount calculation unit 16 sets the correction area edge 701-1 and the correction area edge 701-2 so as to include the initial peak distance 801 as shown in FIG. 6, and the correction area edge 701-1 and the correction area edge 701- 2 is set to a position where the distance to 2 is the correction area width. The shift amount calculation unit 16 detects the measurement peak distance 802a as the peak position of the monitoring target waveform 402a as shown in FIG. 6 within the range from the correction region end 701-1 to the correction region end 701-2. The shift amount calculation unit 16 calculates the shift amount 601 by subtracting the initial peak distance 801 from the detected measurement peak distance 802a.
The positional relationship between the correction area end 701-1, the initial peak distance 801, and the correction area end 701-2 on the distance axis is a value set based on statistics based on past measurement results, for example, an initial value The positional relationship preset by the user, such as setting the position of the correction area end 701-1 on the distance axis to the position where the distance from the peak distance 801 is a value obtained by multiplying the correction area width by a constant rate, may be output. The shift amount calculation unit 16 may be set by a user operation with reference to the waveform displayed on the screen by the unit 18.

The correction unit 17 shifts the input monitoring target measurement waveform in accordance with the shift amount 601 and outputs it as corrected monitoring target measurement information to the waveform analysis unit 11 (step S7).
When the correction monitoring target measurement information is input, the waveform analysis unit 11 outputs normal peak information, normal measurement information, and correction monitoring target measurement information to the determination unit 15.
The determination unit 15 determines whether there is an abnormality in the peak of the corrected monitoring target measurement waveform for each measurement point of the input normal peak information (step S8). If the determination unit 15 determines that there is no abnormality in the waveform, the determination unit 15 outputs a determination result that the measurement information at the corresponding measurement point is normal to the output unit 18 and ends the process (step S9). If the determination unit 15 determines that the waveform is abnormal, the determination unit 15 outputs an alarm that the measurement information at the corresponding measurement point is abnormal and a determination result to the output unit 18 and ends the process (step S10).

The determination method in step S8 is performed by the following operation, for example. The determination unit 15 subtracts the light intensity value of the correction monitoring target measurement information at the initial peak position from the light intensity value of the initial peak position due to the reflected light from each measurement point in the waveform formed by the normal measurement information. Calculate the resulting difference.
Next, the determination unit 15 determines whether or not the calculated difference value of the light intensity value exceeds a predetermined peak abnormality detection threshold value. When the determination unit 15 detects that the difference in the light intensity value at the peak of the normal measurement information exceeds the peak abnormality detection threshold, the determination unit 15 determines that the abnormality is present.
This threshold value for peak abnormality detection is a value set based on statistics based on past measurement results, and may be set in advance by the user, for example, a constant rate determined by the user based on statistics based on past measurement results May be set as a value that varies according to the measurement information, such as a value obtained by multiplying the maximum light intensity value of the measurement information.

  Next, the operation for calculating the shift amount in step S7 will be described with reference to FIG. 7 when a plurality of peaks are detected in the correction range due to factors such as construction in the monitoring target measurement waveform. FIG. 7 is an enlarged view of a part of the partial measurement information display area 301 when two peaks are detected in the correction range in the monitoring target waveform 402b.

As shown in FIG. 7, the shift amount calculation unit 16 measures the measurement peak distance 802b-1 and the measurement peak distance 802b-1 as the peak position of the monitoring target waveform 402b within the correction range from the correction region end 701-1 to the correction region end 701-2. The peak distance 802b-2 is detected.
The shift amount calculation unit 16 subtracts the initial peak distance 801 from the detected measurement peak distance 802b-1 to subtract the shift amount 601-1, and subtracts the initial peak distance 801 from the measurement peak distance 802b-2. 2 is calculated. The shift amount calculation unit 16 compares the calculated shift amount 601-1 and the shift amount 601-2, and outputs the shift amount 601-1 having a value close to 0 to the correction unit 17 as a correct shift amount.

  Note that the shift amount is output assuming that the normal peak is shifted from the measured peak distance 802b-1 closer to the initial peak distance 801. In addition to this method, the normal value at the initial peak distance 801 is normal. Using the light intensity of the hourly measurement waveform 401 as the reference light intensity, the light intensity at the measurement peak distance 802b-1 and the measurement peak distance 802b-2 of the monitoring target waveform 402b is obtained, and the difference value obtained by subtracting the reference light intensity is The shift amount may be calculated with a value closer to 0 as a peak shifted from a normal peak.

As other methods for calculating the shift amount, a method using an average of the shift amounts at two or more measurement points, a method for calculating the shift amount for each measurement point based on the ratio of the shift amount to the distance at the measurement point, and the like Is also applicable.
According to these operations for calculating the shift amount, in the monitoring target measurement waveform after the construction, there are cases where the peaks due to the reflected waves from the ONUs 120-1 to 120-N are close and there are a plurality of peaks within the correction range. However, even in such a case, it is possible to prevent malfunction of the monitoring device.

  In the present embodiment, the reflected light from the ONUs 120-1 to 120-N is taken as an example of return light, but the connection points and fusion of the optical fibers 60, 70-1 to 70-M, 80-1 to 80-N are used. Reflected light at points, reflected light from the optical filters by the splitters 101 and 110 and the above-described FBG, and backscattering due to Rayleigh scattering inherent in the optical fibers 60, 70-1 to 70-M and 80-1 to 80-N. Light may be used.

  In the present embodiment, the determination unit 15 determines whether the difference between the light intensity values of the normal measurement information and the monitoring target measurement information exceeds the peak abnormality detection threshold value, so that the monitoring target measurement waveform is determined. Although it was determined whether or not it was abnormal, the waveform width value of the peak portion extracted from the normal measurement waveform and the waveform width value of the waveform portion extracted from the monitored measurement waveform were calculated and calculated. It may be determined whether or not the difference between the waveform width values exceeds a predetermined waveform width abnormality detection threshold, whether it is abnormal, or determination based on the peak abnormality detection threshold and waveform width abnormality The determination based on the detection threshold may be combined, or an existing abnormality determination method may be used.

Specifically, the determination using the waveform width abnormality detection threshold is performed according to the following procedure.
The determination unit 15 extracts the waveform portion of the normal measurement waveform 401 and the waveform portion of the monitoring target waveform 402 based on a predetermined waveform portion specifying threshold. Then, the determination unit 15 calculates the waveform width of each extracted waveform portion.
This waveform part specifying threshold is a value set based on statistics based on past measurement results, and may be set in advance by the user, for example, in the measurement information such as 50% of the maximum light intensity value of the measurement information. It may be set as a value that varies correspondingly, or may be set in the determination unit 15 by a user operation with reference to a waveform displayed on the screen by the output unit 18.

  Specifically, as illustrated in FIG. 8, the determination unit 15 includes the intersection 951-1 and the intersection 951 between the light intensity value (reference numeral 500) of the waveform portion specifying threshold and the normal measurement waveform 401 of the normal measurement information. -2 is detected, the difference obtained by subtracting the value on the intersection 951-1 distance axis from the value on the distance axis of the intersection 951-2 is calculated, and the calculated difference is used as the waveform width (waveform width 651). . Similarly, for the monitoring target waveform 402a, the determination unit 15 detects the intersection 952a-1 and the intersection 952a-2 between the light intensity value (reference numeral 500) of the waveform portion specifying threshold and the monitoring target waveform 402a. Then, a difference obtained by subtracting the value on the intersection 952a-1 distance axis from the value on the distance axis of the intersection 952a-2 is calculated, and the calculated difference is set as a waveform width (waveform width 652a).

  Then, the determination unit 15 determines whether or not there is an abnormality in the peak depending on whether or not the difference obtained by subtracting the waveform width 652a from the calculated waveform width 652a exceeds the waveform width abnormality detection threshold described above. To do. When the determination unit 15 detects that the difference in the calculated waveform width value exceeds the waveform width abnormality detection threshold value, the determination unit 15 determines that the difference is not abnormal and the difference in the waveform width value does not exceed the waveform width abnormality detection threshold value. Is detected, it is determined that there is no abnormality, that is, normal.

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

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 addition, the present invention may have any configuration as long as it utilizes the characteristic that the waveform shape does not change even when the optical fiber is expanded or contracted, and may be configured to compare the entire waveforms.

  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 drawing which shows an example of the normal time peak information memorize | stored in measurement information DB12 in the embodiment. 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 shift amount in the embodiment. It is a figure for demonstrating the calculation means of shift amount when the peak in the embodiment exists closely. It is a figure for demonstrating the calculation means of the waveform width in the same embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Optical transmission line monitoring apparatus, 10 ... Connection part, 11 ... Waveform analysis part, 12 ... Measurement information DB, 14 ... Operation part, 15 ... Determination part, 16 ... Shift amount calculation part, 17 ... Correction part, 18 ... Output , 30 ... optical fiber, 40 ... optical switch, 50 ... measuring device, 60 ... optical fiber, 70-1 to 70-M ... optical fiber, 80-1 to 80-N ... optical fiber, 90 ... transmission device, 100 Directional coupler, 101, splitter, 110, splitter, 120-1 to 120-N, ONU, 200-1 to 200-L, optical fiber, 300, all measurement information display area, 301, partial measurement information display area , 302 ... area frame, 400 ... waveform display screen, 400 a ... waveform display screen, 401 ... normal measurement waveform, 402 ... monitoring target waveform, 402a ... monitoring target waveform, 402b ... monitoring target waveform, 601 ... shift amount, 01-1 ... shift amount, 601-2 ... shift amount, 701-1 ... correction region end, 701-2 ... correction region end, 801 ... initial peak distance, 802a ... measurement peak distance, 802b-1 ... measurement peak distance, 802b-2 ... Measurement peak distance

Claims (8)

One of the measurement information including a light intensity value for each distance of the optical transmission line obtained by analyzing a returning light which is measured by incidence of light pulses in the longitudinal direction of the fiber optic constituting the optical transmission line a normal time of measurement information, and the normal time of measurement information, in the optical transmission line monitoring equipment for detecting an abnormality of the optical transmission line based expansion of the optical fiber to be monitored within the measurement information in the unknown state There,
A first detection means to detect a first waveform portion which includes a peak of at least one waveform in the waveform formed from the said light intensity value and the distance that is included in the normal time of measurement information,
A second waveform portion that detects a second waveform portion corresponding to the first waveform portion in the waveform of the measurement information to be monitored within a predetermined correction range including a peak of the first waveform portion; and detection hand stage,
Bei said first waveform portion, said on the basis of the second waveform portion in which the second detecting means detects the abnormality detecting hand stage of performing abnormality detection Te waveform odor of measurement information of the monitoring target e,
The first detection means includes
As information for specifying the first waveform portion, a peak distance value of the first waveform portion is detected,
The second detection means includes
Detecting a value of a peak distance of the second waveform portion within the correction range in the measurement information of the monitoring target;
The abnormality detection means includes
The shift amount for correcting the shift of the distance value of the second waveform portion with respect to the first waveform portion is expressed by a peak distance value of the first waveform portion and a peak of the second waveform portion. Shift amount calculating means for calculating based on the distance value of
Correction means for correcting the distance value of the second waveform portion with the shift amount calculated by the shift amount calculation means;
A first determination unit that determines whether or not there is an abnormality by comparing the second waveform portion corrected by the correction unit with the first waveform portion;
A first output means for outputting an abnormality when the first determination means determines that there is an abnormality;
An optical transmission line monitoring device comprising: Among the waveforms of the measurement information to be monitored, the distance value of the second waveform portion corresponding to the first waveform portion is determined from the distance value of the first waveform portion due to the expansion and contraction of the optical fiber. the optical transmission line monitoring apparatus according to the shift amount predicted value to claim 1, further comprising a correction range calculation means to calculate as the correction range. Among the waveforms of the measurement information to be monitored, the distance value of the second waveform portion corresponding to the first waveform portion is determined from the distance value of the first waveform portion due to the expansion and contraction of the optical fiber. The optical transmission line monitoring apparatus according to claim 1, further comprising storage means for storing the correction range set in advance by a user as a shift amount prediction value. The second detection means includes
The waveform having the peak closest to the peak of the first waveform portion when a plurality of waveform portions corresponding to the first waveform portion are detected within the correction range in the waveform of the measurement information to be monitored 4. The optical transmission line monitoring apparatus according to claim 1 , wherein a portion is detected as the second waveform portion. 5. Further comprising a measurement information storage means to store as a reference waveform at least one of first waveform portions detected by the first detecting means,
The second detection means includes
In the waveform of the measurement information to be monitored, a second waveform portion corresponding to the reference waveform is detected,
The abnormality detection means includes
The abnormality detection is performed without depending on expansion and contraction of the optical fiber by correcting the entire waveform of the measurement information to be monitored based on the reference waveform and the second waveform portion. The optical transmission line monitoring apparatus according to any one of claims 1 to 4 . A plurality of first waveform portions detected by the first detection means as reference waveforms, further comprising measurement information storage means for storing in correspondence with reference priority numbers indicating priority orders;
The shift amount calculating means includes
The shift amount for correcting the shift of the distance value with respect to the reference waveform of the second waveform portion is set to the peak distance value of the reference waveform and the peak distance value of the second waveform portion. When calculating as a reference shift amount based on the above, if a waveform portion corresponding to the reference waveform having the reference priority number N (N is an integer starting from 1) does not exist within the correction range,
A waveform portion corresponding to the reference waveform having the reference priority number N + 1 is defined as a second waveform portion, and the distance value shifts based on the reference waveform having the reference priority number N + 1 and the second waveform portion. An optical transmission line monitoring apparatus according to any one of claims 1 to 5, wherein a shift amount for correcting the shift is calculated. 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 first step of detecting a first waveform portion including a peak of at least one waveform among waveforms formed from the distance and the light intensity value included in the normal measurement information;
A second waveform portion that detects a second waveform portion corresponding to the first waveform portion in the waveform of the measurement information to be monitored within a predetermined correction range including a peak of the first waveform portion ; Steps,
Wherein said first waveform portion detected in the first step, the second on the basis of the second waveform portion detected in step, abnormal detection Te waveform odor of measurement information of the monitoring target look including an abnormality detection step of performing,
The first step includes
As information for specifying the first waveform portion, a peak distance value of the first waveform portion is detected,
The second step includes
Detecting a value of a peak distance of the second waveform portion within the correction range in the measurement information of the monitoring target;
The abnormality detection step includes:
The shift amount for correcting the shift of the distance value of the second waveform portion with respect to the first waveform portion is expressed by a peak distance value of the first waveform portion and a peak of the second waveform portion. A shift amount calculating step to calculate based on the distance value of
A correction step of correcting the distance value of the second waveform portion with the shift amount calculated by the shift amount calculation step;
A first determination step for determining whether or not there is an abnormality by comparing the second waveform portion corrected in the correction step with the first waveform portion;
A first output step for outputting an abnormality when the first determination step is determined to be abnormal;
The optical transmission line monitoring method, which comprises a. 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. To the computer of the optical transmission line monitoring device that detects abnormality of the optical transmission line based on the normal time measurement information and the measurement information when the expansion and contraction of the optical fiber to be monitored is unknown ,
The detection of the first waveform portion including the peak of the at least one waveform in the waveform formed from the said light intensity value and the distance that is included in the normal time of measurement information, identifies the first waveform portion A first step of detecting and detecting a peak distance value of the first waveform portion as information ;
The detection of the second waveform portion corresponding to the first waveform portion in the waveform of the measurement information to be monitored is performed within the predetermined correction range including the peak of the first waveform portion. A second step performed by detecting a value of a peak distance of the second waveform portion within the correction range in measurement information of an object ;
Said first waveform portion detected by the first step, on the basis of the second waveform portion detected by the second step, the waveform of the measurement information of the monitoring target, the second The shift amount for correcting the shift of the distance value of the first waveform portion with respect to the first waveform portion is expressed by the peak distance value of the first waveform portion and the peak distance of the second waveform portion. By calculating a distance value of the second waveform portion with the shift amount, and comparing the corrected second waveform portion with the first waveform portion. A monitoring program for determining whether there is an abnormality, and executing a step of outputting that there is an abnormality when it is determined that there is an abnormality .

Images