JP7178643B2 - OTDR measuring device and OTDR measuring method - Google Patents

Description

The present invention relates to an OTDR measuring apparatus and an OTDR measuring method, and more particularly to a technology for appropriate event detection when the subject is an optical transmission line including multiple optical fibers such as a patch cord.

An optical pulse tester called an OTDR (Optical Time Domain Reflectometer) generally generates pulsed light with a short time width and sends this pulsed light to one end of an optical fiber to be measured. When the light that has entered the optical fiber propagates inside the optical fiber, part of the light generates scattered light due to the glass inside. This scattered light includes what is called "Rayleigh scattering". Since part of the scattered light generated inside the optical fiber propagates inside the optical fiber and returns to the incident end, the optical pulse tester can observe the scattered light at the incident end of the optical fiber.

The time difference from when the pulsed light is incident on the optical fiber until the scattered light is observed at the incident end varies depending on the distance between the incident end of the optical fiber and the location where the scattered light is generated. Therefore, the time-series change in the received light level of the scattered light observed at the incident end of the optical fiber represents the distribution of scattered light generation at each location of the optical fiber. The optical pulse tester can display such a distribution situation.

For example, if an OTDR measuring device is connected to one end of a communication network composed of optical fiber transmission lines, it is possible to obtain information representing the configuration and status of each part of the communication network. Specifically, the amount of reflection and normal transmission loss that occurs at the optical connector that connects optical fibers, and the presence or absence of reflection and abnormal loss due to connection failure or deterioration. It can be specified for each location. Also, the place where the loss occurs can be identified based on the time difference from when the pulsed light is incident on the optical fiber until the corresponding scattered light is observed at the incident end.

For example, in Patent Document 1, when each optical fiber provided in a multi-core optical fiber cable is connected and an optical pulse test is performed as one optical fiber, the distance from the optical pulse test device and the measurement of each optical fiber A technique for making it easier to understand the correspondence with waveforms is disclosed. Specifically, in the optical pulse test apparatus of Patent Document 1, a first optical fiber and a second optical fiber are laid side by side, and the distal end of the first optical fiber is connected to the distal end of the second optical fiber. a measuring unit for measuring the backscattered light in the optical fiber to be measured, a detecting unit for detecting the light loss point from the measured waveform, and the far end and the near end of the second optical fiber from among the light loss points and a reversal unit for reversing the far-to-proximal arrangement into a near-to-proximal arrangement. Also, it is shown that a plurality of transmission lines of a subject are connected by an optical fiber patch cord. Also shown is obtaining the length of the patch cord and locating it.

JP 2018-169233 A

By adopting the technique disclosed in Patent Document 1, the optical pulse test apparatus connects a plurality of optical fibers included in the entire multi-core optical fiber cable to each other, collects them into one optical fiber, and performs one optical fiber. It becomes possible to measure the whole only by testing the It is also possible to display the correspondence relationship between the distance from the optical pulse test apparatus and the measured waveform of each optical fiber in an easy-to-understand manner.

For example, while the far end of the first optical fiber and the far end of the second optical fiber are connected with a patch cord, an optical pulse is sent from the optical pulse test device to the proximal end of the first optical fiber, and the first and the second optical fiber are observed at the proximal end of the first optical fiber. In this case, the time series change in the return light level reflects the state at each position of the optical transmission line including the first optical fiber and the second optical fiber.

However, the actual situation is that the patch cord length (theoretical value or standard value) that can be grasped in advance by a user such as an operator who uses the optical pulse test apparatus does not necessarily match the actual length.

If the patch cord length value pre-entered by the user into the optical pulse tester differs from the actual length, an error may occur in the test results displayed by the optical pulse tester. That is, there is a deviation in the correspondence relationship between the timing of each part of the waveform of the return light grasped by the optical pulse tester and the regions of the first optical fiber and the regions of the second optical fiber. As a result, there is a possibility that the optical pulse test apparatus may mistakenly recognize an event occurring in the patch cord and an event occurring in the optical transmission line of the object, for example.

For this reason, correct test results may not be obtained unless the user manually performs some corrective operation for the occurrence positions of each event after measurement by the optical pulse test apparatus.

SUMMARY OF THE INVENTION The present invention has been made in view of the above situation, and its object is to enable a user to test a patch cord or the like included in an optical transmission line to be tested, even if the actual length is different from the length of the patch cord. An object of the present invention is to provide an OTDR measuring apparatus and an OTDR measuring method capable of outputting correct test results without requiring correction operation.

In order to achieve the above object, an OTDR measuring device and an OTDR measuring method according to the present invention are characterized by the following (1) to (8).
(1) A predetermined optical transmission line including one or more optical fibers and a patch cord is used as an object, an optical pulse is sent to the proximal end of the patch cord, and the return light from the optical fiber is transmitted to the proximal end of the patch cord. An OTDR measuring device that measures the state of the optical transmission line by observing on the side,
an event detection unit that detects, as an event, each event that occurs according to the configuration and state of the optical transmission line based on the observation state of the time-series level change of the returned light;
a cord length determination unit that determines the theoretical value of the optical fiber length of the patch cord as the cord length;
an event correction unit that automatically determines and corrects an event erroneous detection that occurs in the event detection unit in relation to the code length;
An OTDR measuring device comprising:

(2) The event correction unit
determining a reference position corresponding to the code length and an error range of the code length;
At least one of each event range, the start point of each event, and the end point of each event detected by the event detection unit is compared with the reference position or the error range, and a process according to the result is performed.
The OTDR measuring device according to (1) above.

(3) The event correction unit
Having a condition table for pre-holding information representing a correspondence relationship between a condition to be compared and a type of processing to be executed for each case for each of a plurality of cases related to the code length,
The OTDR measuring device according to (2) above.

(4) The event correction unit adds a specific event associated with the reference position when the start point of any event is not included in the error range.
The OTDR measuring device according to (2) above.

(5) When the position to add the specific event is within the range between the start point and the end point of any of the events, the event correction unit adjusts the position of the end point of the corresponding event to the position of the end point of the event. moving one data point forward from a reference position and adding the specific event;
The OTDR measuring device according to (4) above.

(6) When the start point of any event is included in the error range, the event correction unit associates the type of the event whose start point is closest to the reference position with the reference position. change to a specific event,
The OTDR measuring device according to (2) above.

(7) The event correcting unit automatically determines an event erroneous detection occurring in the event detecting unit in relation to the code length for each of the plurality of waveforms output in an overlapping state and having different ranges. to correct,
The OTDR measurement device according to any one of (1) to (6) above.

(8) A predetermined optical transmission line including one or more optical fibers and a patch cord is used as an object, an optical pulse is sent to the proximal end of the patch cord, and the return light from the optical fiber is transmitted to the proximal end of the patch cord. An OTDR measurement method for measuring the state of the optical transmission line by observing on the side,
a step of detecting, as an event, each phenomenon that occurs according to the configuration and state of the optical transmission line, based on the observation state of the time-series level change of the returned light;
determining the theoretical value of the optical fiber length of the patch cord as the cord length;
a step of automatically determining and correcting an event false detection that occurs in detecting the event in relation to the code length;
A method for measuring an OTDR comprising

According to the OTDR measuring apparatus having the configuration of (1) above and the OTDR measuring method having the configuration of (8) above, the cord length representing the length of the patch cord or the like included in the optical transmission line to be tested, Even if the length is different from the actual length, the event correcting unit automatically judges and corrects erroneous event detection caused by the length. Therefore, even if the user does not perform a special correction operation after measurement, correct test results can be output.

According to the OTDR measuring device having the above configuration (2), each event range detected by the event correction unit, at least one of the start point of each event, and the end point of each event, and the reference position or the error range. Since the processing is executed reflecting the comparison result, it is possible to automatically execute appropriate correction processing in accordance with the situation at that time in various situations.

According to the OTDR measurement apparatus having the configuration (3) above, the event correction section can automatically perform appropriate correction processing according to the conditions of the case at that time, according to the contents of the condition table.

According to the OTDR measurement apparatus having the configuration (4) above, even if there is an error in the length of the patch cord or the like included in the optical transmission line to be tested, the event of reflection or attenuation generated by the patch cord is The influence can be correctly reflected in the display or the like.

According to the OTDR measurement device having the configuration (5) above, the position of the specific event to be added and the range of another event that was detected before that are prevented from overlapping on the data or on the display. can be automatically corrected to distinguish between

According to the OTDR measurement device having the configuration (6) above, by changing the type of event detected before correction to a specific event, the effect of the patch cord included in the optical transmission line to be tested It will be possible to correctly classify and output the reflection and attenuation events that occur.

According to the OTDR measuring apparatus having the configuration (7), for example, even when the waveform generated in the forward optical transmission line and the waveform generated in the backward optical transmission line are displayed in an overlay display, each waveform , it is possible to correctly detect events without affecting patch cord length errors.

According to the OTDR measurement apparatus and the OTDR measurement method of the present invention, when an optical transmission line to be tested includes a patch cord or the like, even if there is an error in the length of the patch cord, the user does not need to perform a correction operation. It is possible to output correct test results without

The present invention has been briefly described above. Furthermore, the details of the present invention will be further clarified by reading the following detailed description of the invention (hereinafter referred to as "embodiment") with reference to the accompanying drawings. .

FIG. 1 is a block diagram showing a configuration example of an OTDR measuring device according to an embodiment of the present invention. FIG. 2 is a block diagram showing an example of the connection state of optical cables during testing. FIG. 3 is a flow chart showing a characteristic operation example of the OTDR measuring device. FIG. 4 is a schematic diagram showing a configuration example of an event correction condition table. FIG. 5 is a schematic diagram showing a configuration example of a correction processing table. 6(a), 6(b), 6(c), 6(d), and 6(e) show the relationship between the time-series light intensity distribution of the return light and the event under different conditions. It is a time chart showing. 7(a), 7(b), 7(c), 7(d), 7(e), and 7(f) show the time-series light intensity distributions of the returned light under different conditions. 4 is a time chart showing the relationship between , and events. FIG. 8 is a front view showing the main part of a screen display example of the OTDR measuring device.

Specific embodiments relating to the present invention will be described below with reference to each drawing.

<Configuration of OTDR measuring device>
FIG. 1 shows a configuration example of an OTDR measuring device 30 according to an embodiment of the present invention.

The OTDR measuring device 30 shown in FIG. 1 is composed of the optical pulse tester body 10 and the event processing device 20 . The optical pulse tester main body 10 is connected to one end (near end) of an optical cable 100 of a subject.

Similar to a general optical pulse tester, the optical pulse tester body 10 generates pulsed light with a short time width and feeds this pulsed light into one end of the optical fiber to be measured. When the light incident on the optical fiber propagates inside the optical fiber, part of the light is reflected by the glass inside to generate scattered light. This scattered light includes what is called "Rayleigh scattering". Since part of the scattered light generated inside the optical fiber propagates inside the optical fiber and returns to the incident end, the optical pulse tester body 10 can observe the scattered light as returned light at the incident end of the optical fiber.

The time difference from when the pulsed light enters the optical fiber of the subject until the scattered light is observed at this incident end changes according to the distance between the incident end of the optical fiber and the location where the scattered light occurs. . Therefore, the time-series change in the received light level of the scattered light observed at the incident end of the optical fiber represents the distribution of scattered light generation at each location of the optical fiber. It is observed as a light intensity distribution that changes in time series like the light intensity waveform Wo.

The event processing device 20 connected to the optical pulse tester main body 10 grasps the state of each part of the optical transmission line such as the optical cable 100 of the test object based on the time-series light intensity distribution observed by the optical pulse tester main body 10. It has a function to display the result.

In other words, the optical transmission path of the subject has a plurality of parts such as a plurality of optical fibers and optical connectors that are independent of each other, and light loss and reflection occur at each part. It has a function of detecting each characteristic as an event and determining whether each event is normal or not. This makes it possible to diagnose, for example, failures, poor connections, deterioration, etc. of each part.
The event processing device 20 of this embodiment also has a processing function for automatically correcting an error in an event detected by a normal method.

The event processing device 20 shown in FIG. 1 includes an observation data recording unit 21, an event detection unit 22, an event data storage unit 23, an event correction unit 24, a parameter storage unit 25, an event correction condition table 26, a display unit 27, and an operation unit. An input unit 28 is provided.

The observation data recording unit 21 is a memory for recording and holding a large amount of data obtained by sampling the return light intensity waveform Wo (see FIG. 6A) observed by the optical pulse tester main body 10 during the test at regular time intervals and digitizing the data. It has

The event detection unit 22 analyzes the data of the return light intensity waveform Wo recorded by the observation data recording unit 21, and detects various events included in this waveform. Also, by comparing the pattern of the magnitude of the reflected wave, the amount of attenuation, etc. in each event with a predetermined threshold value, the type of event can be identified. Also, the position or distance at which each event occurs can be detected based on the time on the returned light intensity waveform Wo.
For example, the event detection unit 22 can be configured using the known technology described in Japanese Patent Application Laid-Open No. 2012-167935.

The event data holding unit 23 is composed of a memory to which data can be freely written and read, and can hold the data of each event detected by the event detection unit 22 as data associated with the detected position. The data of each event includes information such as the type of event, event start point, event end point, event range, magnitude of reflected wave, and magnitude of loss before and after the event.

The event correction unit 24 has a special processing function for correcting errors in each event detected by the event detection unit 22 and adding new events. Information necessary for executing this processing function is stored in the event correction condition table 26 in advance.

The parameter holding unit 25 is configured by, for example, a non-volatile memory, and includes parameters necessary for the event detection unit 22 to identify the type of event, parameters used by the event correction unit 24, and determination of the presence or absence of problems in each event. Data such as various threshold values for Each data held by the parameter holding unit 25 can be updated according to an input from the operation input unit 28, for example.

Typical data held by the parameter holding unit 25 is a patch cord length Lpc representing the length of a patch cord included in the optical transmission line, which is the subject.

The display unit 27 has a two-dimensional display screen composed of a full-color liquid crystal display panel or the like. The display unit 27 displays measurement results held by the event data holding unit 23, displays parameters held by the parameter holding unit 25, and displays information necessary for updating each parameter. Available. For example, as in the example shown in FIG. 8, each event detected on the optical cable 100 of the subject can be displayed on the screen of the display unit 27 as a display pattern of a plurality of icons.

The operation input unit 28 includes various buttons that can be operated by the user, a touch panel that is superimposed on the screen of the display unit 27, and the like. User input from the operation input unit 28 can control the operation of the OTDR measurement device 30 and change the parameters held by the parameter holding unit 25 .

The main control elements in the event processing device 20 include, for example, control computer hardware, computer basic software (OS), and special application software prepared for event processing. be done.

<Connection status of optical cable>
FIG. 2 shows an example of the connection state of the optical cable 100 to be tested when the OTDR measuring device 30 is used for testing.

In the optical communication equipment, for example, an optical connector 104 for relay is arranged at an intermediate portion between the proximal fiber end 101a and the distal fiber end 102b.

In the example of FIG. 2, when an optical transmission line such as the optical cable 100 is tested using the OTDR measurement device 30, the fiber near end 101a of one optical fiber 101 is replaced with the far end 105b of the patch cord 105 composed of optical fibers. , and the proximal end 105 a is connected to the main body 10 of the optical pulse tester. Moreover, in an actual test, it is assumed that the patch cord 105 is connected to the rear of the fiber distal end 102b of the optical cable 100 and also between the optical pulse tester body 10 and the fiber proximal end 101a of the optical cable 100. be done.

Here, when the patch cord 105 is connected as shown in FIG. 2, it is necessary to separate the events occurring at the connection points of the patch cord 105, the optical fiber 101, and the optical fiber 102 and correctly recognize them. be. Also, if there is a patch cord 105 between the optical pulse tester body 10 and the optical fiber 101 behind the fiber distal end 102b of the optical cable 100, it is separated to detect events on each optical path. There is a need. However, the theoretical value or standard value (patch cord length Lpc) of the patch cord 105 that can be grasped in advance by a user such as an operator may deviate from the actual length. Due to this length deviation, the OTDR measuring device 30 grasps each event occurring at each connection point of the patch cord 105, the optical fiber 101, and the optical fiber 102 in a state where the respective positions are shifted. there's a possibility that. Therefore, a user such as an operator may not be able to correctly grasp the state of the optical transmission line of the object.

In the OTDR measurement device 30 of the present embodiment, the event correction unit 24 in the event processing device 20 determines the length of the patch cord 105 or the like (patch cord length Lpc) connected to the optical transmission line of the subject during testing. , has processing capabilities to automatically correct event detection errors due to deviations from its actual length. This processing function is described below.

<Characteristic example of operation>
FIG. 3 shows a characteristic operation example of the OTDR measurement device 30 in this embodiment. The operation shown in FIG. 3 will be described below.

The event correction unit 24 of the event processing device 20 determines the unique patch cord length Lpc of the patch cord 105 connected to the optical cable 100, which is the subject (S11). In practice, the user inputs a numeric value of the length of the patch cord 105 that can be grasped in advance by the user through the operation input unit 28, and the parameter holding unit 25 holds this numeric value. Therefore, the event correction section 24 acquires the patch cord length Lpc from the parameter holding section 25 .

In the next step S12, the OTDR measuring device 30 starts testing the optical paths under test, that is, the optical paths of the patch cord 105, the optical fibers 101, and the optical fibers 102 shown in FIG. Specifically, the optical pulse tester main body 10 sends an optical pulse from the proximal end 105a of the patch cord 105 toward the patch cord in accordance with the start instruction according to the user's input operation. Then, the optical pulse tester body 10 receives the return light from each part of the optical path at the proximal end 105a of the patch cord, and observes the time-series waveform of the received light intensity.

The observation data recording unit 21 of the event processing device 20 automatically records the time-series intensity waveform data of the return light observed by the optical pulse tester main body 10, and stores the data in the internal memory (S13).

The event detection unit 22 analyzes the time-series data held in the internal memory of the event processing device 20 to detect the event sequentially from the portion on the optical path closer to the entrance/exit of the optical pulse tester main body 10 . A detection process is performed (S14).

That is, since the returned light reaches the optical pulse tester body 10 in the order from the position of the proximal end 105a of the patch cord to the direction of the distal end 102b of the fiber, by processing the data in the order of arrival time, Events in each part can be detected so as to follow the order of the .

The event detection unit 22 identifies the type of each event detected in S14 (S15). For example, loss according to the characteristics of the fiber itself that occurs in each section on the optical fiber 101, reflection and loss that occur in the optical connector in the optical path, the patch cord 105, etc. are classified as different events for each part. do.

When the processing of all events on the optical path to be detected is completed, for example, when the intensity level of the returned light drops below the noise level and it becomes difficult to identify the backscattered light after that, the processing from S16 to S17 is performed. move on.

The event correction unit 24 determines the reference position Ppc on the return light intensity waveform Wo based on the patch cord length Lpc determined in S11 (S17). That is, on the optical path tested by the OTDR measuring device 30, the position of the boundary corresponding to the fiber proximal end 101a to which the far end 105b of the patch cord 105 is connected is defined as the reference position Ppc.

However, there is a possibility that the patch cord length Lpc determined in S11 and the actual length of the patch cord 105 will differ due to variations in the characteristics of the parts manufactured by the manufacturer. Therefore, the event correction unit 24 determines the error range Rer based on the patch cord length Lpc (S18).

This error range Rer represents the range in which each position is actually expected to exist when considering the expected errors in the position of the fiber distal end 102b and the position of the fiber proximal end 101a. The event correction unit 24 determines the error range Rer as follows.

Rer−1=Lpc−(Lpc×Cc)
Rer−2=Lpc+(Lpc×Cc)
Rer-1: Position of starting point of error range Rer Rer-2: Position of ending point of error range Rer Cc: Correlation coefficient (predetermined constant) representing inherent characteristics of patch cord 105

The event correction unit 24 compares the reference position Ppc, the error range Rer, and each event in the event data holding unit 23 detected by the event detection unit 22, and selects a matching case on the event correction condition table 26. Specify (S19).

The event correction unit 24 executes correction processing corresponding to the case identified in S19 (S20). As a result, a new event is added to the data held in the event data holding unit 23, or the content of an event detected in advance is corrected. Specifically, on the test optical path, the event correction unit 24 adds or changes events for each of the boundary position corresponding to the fiber distal end 102b and the boundary position corresponding to the fiber proximal end 101a.

The display unit 27 displays each event of the test results on the screen based on the data in the event data holding unit 23 after the correction processing of S20 (S21). As a result, a screen such as that shown in FIG. 8, for example, is displayed.

<Configuration example of event correction condition table>
FIG. 4 shows a configuration example of the event correction condition table 26 used by the OTDR measurement device 30 of this embodiment.

As shown in FIG. 4, the event correction condition table 26 lists information representing individual conditions 26a, 26b, 26c, 26d, and 26e and an assigned processing category 26f for each of the case categories CS1 to CS8. keeping.

The individual condition 26a indicates whether or not the "designated distance" is within the event by the difference of "O/X". This "designated distance" is a distance corresponding to the reference position Ppc in FIG.
The individual condition 26b indicates whether or not the predetermined "range C" is within the event by the difference of "o/x". This "range C" corresponds to the error range Rer in FIG.

The individual condition 26c indicates whether or not the starting point of the event is within the predetermined "range C" by the difference between "O/X". The individual condition 26d indicates whether or not the end point of the event is within the predetermined "range C" by the difference between "O/X". The individual condition 26e represents the number of events "0, 1, 1 or more" included in a predetermined "range C".

The processing section 26f represents one of processing PA, PB, and PC.

For example, in the event correction condition table 26 of FIG. 4, in the case of case classification CS2, the individual condition 26a is not met (x), the individual condition 26b is met (o), the individual condition 26c is met (o), and the individual condition 26d is , the number of events of the individual condition 26e is "1", and the processing section 26f is processing PC.

That is, when all the combinations of these conditions match, the case is classified as case classification CS2. Therefore, in that case, it means that the event correction unit 24 executes the "processing PC" shown in the processing section 26f of the case section CS2.

<Configuration example of correction processing table>
FIG. 5 shows a configuration example of the correction processing table TB2 used by the OTDR measurement device 30 of this embodiment. This correction processing table TB2 is held in the internal memory of the event correction unit 24, for example.

In addition to the event correction condition table 26, the event processing device 20 shown in FIG. 1 also has a correction processing table TB2 shown in FIG. This correction processing table TB2 represents the correspondence relationship between the categories of processing PA, PB, PC, and common processing Po and their specific contents.

For example, if the case category CS1 shown in FIG. 4 is applied, the processing category 26f indicates "processing PA", so the event correction unit 24 corresponds to "processing PA" in FIG. Perform content processing.

4, "Processing PB" is indicated in the processing section 26f, so that the event correction unit 24 performs the content corresponding to "Processing PB" in FIG. Execute the process.

4, "Processing PC" is indicated in the processing section 26f, so that the event correction unit 24 selects the content corresponding to "Processing PC" in FIG. Execute the process. In addition, the event correction unit 24 executes the process corresponding to the "common process Po" in FIG. 5 for any of the case categories CS1 to CS8.

As shown in FIG. 5, in the case of "process PA", a process of adding a "PatchCord event" to the designated position is executed. That is, that position is the boundary position where the rear end of the patch cord 105 is actually connected.

In the case of "process PB", the process of adding a "PatchCord event" to the specified position is executed, and the end point of the existing event is the data point position "-1DP" one position before the added position. is corrected to move to Other data are left as they are. Thereby, it is possible to separate the ranges of a plurality of events so that they do not overlap each other.

In the case of "processing PC", the type of the event closest to the designated distance among the start points of the events within range C is changed to "PatchCord event".

Further, the "common process Po" is executed for any of the processes PA, PB, and PC. In the "common process Po", the shift length is corrected so that the position of the added or changed "PatchCord event" is obtained.

<Specific examples of waveforms and events>
FIGS. 6A to 6E and 7A to 7F show examples of the relationship between the waveform of the time-series light intensity distribution of the return light and events under different conditions. Each figure shows a return light intensity waveform Wo, a plurality of events EV1, EV2, and EV3 detected by the event detector 22, a reference position Ppc, and an error range Rer. In each figure, the horizontal axis represents the time t after the return light first arrives and the distance d from the tester in the optical path under test, and the vertical axis represents the light intensity.

The reference position Ppc shown in FIGS. 6(a) to 6(e) and 7(a) to 7(f) is determined based on the patch cord length Lpc as described above. 2 corresponds to the connection point between the patch cord far end 105b and the fiber proximal end 101a. However, if the patch cord length Lpc does not match the actual length of the optical cable 100, the actual position of the proximal end 101a of the fiber is considered to be somewhere within the error range Rer in each figure. . 6A to 6E and 7A to 7F show the relationship between the reference position Ppc, the error range Rer, and the events EV1 to EV3 depending on the actual situation. may change as

6(a), 6(b), 6(c), 6(d), and 6(e) correspond to case categories CS1, CS2, CS3, and CS4 in the event correction condition table 26, respectively. , and CS4. 7(a), 7(b), 7(c), 7(d), 7(e) and 7(f) correspond to case categories CS5, CS6, CS7, respectively. It corresponds to CS8, CS8, and CS8.

As for the position of the proximal end 102a of the fiber shown in FIG. 2, as in FIGS. 6A to 6E and 7A to 7F, each detected event Since the relationship between the position, the reference position Ppc, and the error range Rer is expected to change, the same processing as in the above case is performed.

As for the return light intensity waveform Wo in each figure, the distance d on the optical path increases as time t elapses, so the light intensity gradually attenuates with time t according to the characteristics of the optical fiber. In addition, reflections and losses occur at locations where optical connectors, patch cords 105, and the like exist in the optical path to be tested, so event-based waveforms w1, w2, and w3 corresponding to these influences appear. By analyzing such waveform changes, the event detector 22 detects each of the events EV1 to EV3.

<Description of the situation shown in FIG. 6(a)>
In this example, the reference position Ppc, that is, the designated distance does not exist in any of the events EV1, EV2, and EV3, so it does not correspond to the individual condition 26a in the event correction condition table 26 (x). Also, since the error range Rer, that is, "range C" does not exist in any of the events EV1, EV2, and EV3, it does not correspond to the individual condition 26b in the event correction condition table 26 (x). In addition, since the error range Rer, that is, the starting point of the events EV1, EV2, and EV3 does not exist within the "range C", the individual condition 26c in the event correction condition table 26 is not met (x). In addition, since the error range Rer, that is, the end point of the events EV1, EV2, and EV3 does not exist within the "range C", the individual condition 26d in the event correction condition table 26 is not met (x). Also, the number of events detected within the error range Rer, that is, the “range C” is “0”.

Therefore, based on the event correction condition table 26, the event correction unit 24 recognizes the situation shown in FIG. 6A as case class CS1. Therefore, the correction process of "process PA" is executed.

<Description of the situation shown in FIG. 6(b)>
In this example, since the reference position Ppc does not exist in any of the events EV1, EV2, and EV3, it does not correspond to the individual condition 26a in the event correction condition table 26 (x). Also, since the error range Rer exists within the event range Rev-2 of the event EV2, the individual condition 26b in the event correction condition table 26 is satisfied (○). Also, since the starting point of the event range Rev-2 of the event EV2 exists within the error range Rer, the individual condition 26c in the event correction condition table 26 is satisfied (○). Also, since the end point of the event range Rev-2 of the event EV2 does not exist within the error range Rer, the individual condition 26d in the event correction condition table 26 is not met (x). Also, the number of events detected within the error range Rer is "1".

Therefore, based on the event correction condition table 26, the event correction unit 24 recognizes the situation shown in FIG. 6B as case class CS2. Therefore, the correction process of "processing PC" is executed.

<Description of the situation shown in FIG. 6(c)>
In this example, since the reference position Ppc does not exist in any of the events EV1, EV2, and EV3, it does not correspond to the individual condition 26a in the event correction condition table 26 (x). Also, since the error range Rer exists within the event range Rev-2 of the event EV2, the individual condition 26b in the event correction condition table 26 is satisfied (○). Also, since the starting point of the event range Rev-2 of the event EV2 does not exist within the error range Rer, the individual condition 26c in the event correction condition table 26 is not met (x). Also, since the end point of the event range Rev-2 of the event EV2 exists within the error range Rer, the individual condition 26d in the event correction condition table 26 is satisfied (○). Also, the number of events detected within the error range Rer is "1".

Therefore, based on the event correction condition table 26, the event correction unit 24 recognizes the situation shown in FIG. 6C as case class CS3. Therefore, the correction process of "process PA" is executed.

<Description of the situation shown in FIG. 6(d)>
In this example, since the reference position Ppc does not exist in any of the events EV1, EV2, and EV3, it does not correspond to the individual condition 26a in the event correction condition table 26 (x). Also, since the error range Rer exists within the event range Rev-2 and the event range Rev-3, the individual condition 26b in the event correction condition table 26 is satisfied (○). Also, since the starting point of the event range Rev-3 of the event EV3 is present within the error range Rer, the individual condition 26c in the event correction condition table 26 is satisfied (○). Also, since the end point of the event range Rev-2 of the event EV2 exists within the error range Rer, the individual condition 26d in the event correction condition table 26 is satisfied (○). Also, the number of events detected within the error range Rer is "1 or more".

Therefore, based on the event correction condition table 26, the event correction unit 24 recognizes the situation shown in FIG. 6D as case class CS4. Therefore, the correction process of "processing PC" is executed.

<Description of the situation shown in FIG. 6(e)>
In this example, since the reference position Ppc does not exist in any of the events EV1, EV2, and EV3, it does not correspond to the individual condition 26a in the event correction condition table 26 (x). Also, since the error range Rer exists within the event ranges Rev-1, Rev-2, and Rev-3, the individual condition 26b in the event correction condition table 26 is satisfied (○). Also, since the start points of the event ranges Rev-2 and Rev-3 are present within the error range Rer, the individual condition 26c in the event correction condition table 26 is satisfied (○). Also, since the end points of the event ranges Rev-1, Rev-2, and Rev-3 exist within the error range Rer, the individual condition 26d in the event correction condition table 26 is satisfied (○). Also, the number of events detected within the error range Rer is "1 or more".

Therefore, based on the event correction condition table 26, the event correction unit 24 recognizes the situation shown in FIG. 6(e) as case class CS4. Therefore, the correction process of "processing PC" is executed.

<Description of the situation shown in FIG. 7(a)>
In this example, since the reference position Ppc exists within the event range Rev-2 of the event EV2, the individual condition 26a in the event correction condition table 26 is satisfied (○). Also, since the error range Rer exists within the event range Rev-2, the individual condition 26b in the event correction condition table 26 is satisfied (○). Further, since the start point of any of the event ranges Rev-1 to Rev-3 does not exist within the error range Rer, it does not correspond to the individual condition 26c in the event correction condition table 26 (x). In addition, since there is no end point of any of the event ranges Rev-1 to Rev-3 within the error range Rer, it does not correspond to the individual condition 26d in the event correction condition table 26 (x). Also, the number of events detected within the error range Rer is "1".

Therefore, based on the event correction condition table 26, the event correction unit 24 recognizes the situation shown in FIG. 7A as case class CS5. Therefore, the correction process of "process PB" is executed.

<Description of the situation shown in FIG. 7(b)>
In this example, since the reference position Ppc exists within the event range Rev-2 of the event EV2, the individual condition 26a in the event correction condition table 26 is satisfied (○). Also, since the error range Rer exists within the event range Rev-2, the individual condition 26b in the event correction condition table 26 is satisfied (○). Also, since the starting point of the event range Rev-2 exists within the error range Rer, the individual condition 26c in the event correction condition table 26 is satisfied (○). In addition, since there is no end point of any of the event ranges Rev-1 to Rev-3 within the error range Rer, it does not correspond to the individual condition 26d in the event correction condition table 26 (x). Also, the number of events detected within the error range Rer is "1".

Therefore, based on the event correction condition table 26, the event correction unit 24 recognizes the situation shown in FIG. 7B as case class CS6. Therefore, the correction process of "processing PC" is executed.

<Description of the situation shown in FIG. 7(c)>
In this example, since the reference position Ppc exists within the event range Rev-2 of the event EV2, the individual condition 26a in the event correction condition table 26 is satisfied (○). Also, since the error range Rer exists within the event range Rev-2, the individual condition 26b in the event correction condition table 26 is satisfied (○). Further, since the start point of any of the event ranges Rev-1 to Rev-3 does not exist within the error range Rer, it does not correspond to the individual condition 26c in the event correction condition table 26 (x). Also, since the end point of the event range Rev-2 exists within the error range Rer, the individual condition 26d in the event correction condition table 26 is satisfied (○). Also, the number of events detected within the error range Rer is "1".

Therefore, based on the event correction condition table 26, the event correction unit 24 recognizes the situation shown in FIG. 7C as case class CS7. Therefore, the correction process of "process PB" is executed.

<Description of the situation shown in FIG. 7(d)>
In this example, since the reference position Ppc exists within the event range Rev-2 of the event EV2, the individual condition 26a in the event correction condition table 26 is satisfied (○). Also, since the error range Rer exists within the event range Rev-2, the individual condition 26b in the event correction condition table 26 is satisfied (○). Also, since the starting point of the event range Rev-2 exists within the error range Rer, the individual condition 26c in the event correction condition table 26 is satisfied (○). Also, since the end point of the event range Rev-2 exists within the error range Rer, the individual condition 26d in the event correction condition table 26 is satisfied (○). Also, the number of events detected within the error range Rer is "1".

Therefore, based on the event correction condition table 26, the event correction unit 24 recognizes the situation shown in FIG. 7D as case class CS8. Therefore, the correction process of "processing PC" is executed.

<Description of the situation shown in FIG. 7(e)>
In this example, since the reference position Ppc exists within the event range Rev-2 of the event EV2, the individual condition 26a in the event correction condition table 26 is satisfied (○). Also, since the error range Rer exists in each of the event ranges Rev-1, Rev-2, and Rev-3, the individual condition 26b in the event correction condition table 26 is satisfied (○). Also, since the start points of the event ranges Rev-2 and Rev-3 are present within the error range Rer, the individual condition 26c in the event correction condition table 26 is satisfied (○). Also, since the end points of the event ranges Rev-1 and Rev-2 exist within the error range Rer, the individual condition 26d in the event correction condition table 26 is satisfied (○). Also, the number of events detected within the error range Rer is "3 (one or more)".

Therefore, based on the event correction condition table 26, the event correction unit 24 recognizes the situation shown in FIG. 7(e) as case class CS8. Therefore, the correction process of "processing PC" is executed.

<Description of the situation shown in FIG. 7(f)>
In this example, since the reference position Ppc exists within the event range Rev-2 of the event EV2, the individual condition 26a in the event correction condition table 26 is satisfied (○). Also, since the error range Rer exists in each of the event ranges Rev-2 and Rev-3, the individual condition 26b in the event correction condition table 26 is satisfied (○). Also, since the starting point of the event range Rev-3 exists within the error range Rer, the individual condition 26c in the event correction condition table 26 is satisfied (○). Also, since the end point of the event range Rev-2 exists within the error range Rer, the individual condition 26d in the event correction condition table 26 is satisfied (○). Also, the number of events detected within the error range Rer is "2 (one or more)".

Therefore, based on the event correction condition table 26, the event correction unit 24 recognizes the situation shown in FIG. 7(f) as case class CS8. Therefore, the correction process of "processing PC" is executed.

<Screen display example of OTDR measuring device>
FIG. 8 shows a main portion of a screen display example of the OTDR measuring device 30. As shown in FIG.
In the example shown in FIG. 8, each event occurring in the optical paths on the optical fibers 101 and 102 included in the optical cable 100, which is the object, is numbered. 1, No. 2, No. 3, and no. 4 icon patterns, respectively.

Also, No. 1, No. 2, No. 3, and no. 4 are displayed in a position and arrangement order according to the distance from the tester to each point on the optical cable 100, that is, the distance from the proximal end 101a of the fiber.

<Advantages of OTDR measurement equipment>
In the above-described OTDR measuring apparatus 30, even if the patch cord length Lpc of the patch cord 105 connected to the optical transmission line of the test object is different from the actual length during the test, the fiber proximal end 102a and the fiber proximal end Since the event correction unit 24 automatically corrects the event occurring in 101a, each event on the patch cord 105, the optical fibers 101 and 102 can be corrected without any manual correction operation by a user such as an operator. can be correctly separated and recognized respectively.

In particular, since the event correction condition table 26 as shown in FIG. 4 is used to execute appropriate correction processing prepared in advance for each of the case categories CS1 to CS8, FIGS. Appropriate corrections can be made for various situations as shown in FIGS. 7(a) to 7(f).

Characteristics of the OTDR measurement device described above are summarized and listed briefly in [1] to [8] below.
[1] A predetermined optical transmission line (optical cable 100) including one or more optical fibers (101, 102) and a patch cord 105 is used as an object, and an optical pulse is sent to the proximal end (105a) of the patch cord, An OTDR measuring device (30) for measuring the state of the optical transmission line by observing the return light from the optical fiber at the proximal end side of the patch cord,
an event detection unit (event detection unit 22) for detecting, as an event, each phenomenon that occurs according to the configuration and state of the optical transmission line based on the observation state of the time-series level change of the returned light;
a cord length determination unit (S11) that determines the theoretical value of the optical fiber length of the patch cord as the cord length;
an event correction unit (24) for automatically judging and correcting erroneous event detection occurring in the event detection unit in relation to the code length;
An OTDR measuring device comprising:

[2] The event correction unit (24)
determining a reference position (Ppc) corresponding to the code length and an error range (Rer) of the code length (S17, S18);
At least one of the event range, the start point of each event, and the end point of each event detected by the event detection unit is compared with the reference position or the error range, and a process according to the result of comparison is executed (S19). , S20),
The OTDR measurement device according to [1] above.

[3] The event correction unit (24)
For each of the plurality of cases (CS1 to CS8) related to the code length, information (processing section 26f ) has a condition table (event correction condition table 26) that holds in advance,
The OTDR measurement device according to [2] above.

[4] The event correction unit adds a specific event associated with the reference position when the starting point of any event is not included in the error range (CS1, CS3, CS5, CS7). (treated PA, PB),
The OTDR measurement device according to [2] above.

[5] When the position at which the specific event is added is within the range between the start point and the end point of any of the events (CS2 to CS8), the event correction unit determines the end point of the corresponding event. is moved forward by one data point from the reference position, and the specific event is added (process PB);
The OTDR measuring device according to [4] above.

[6] When the starting point of any of the events is included in the error range (CS2, CS4, CS6, CS8), the event correcting section selects the event whose starting point is closest to the reference position. changing the type to a specific event associated with the reference position (processing PC);
The OTDR measurement device according to [2] above.

[7] The event correction unit automatically determines an event error detection occurring in the event detection unit in relation to the code length for each of the plurality of waveforms output in an overlapping state and having different ranges. correct (S17-S20),
The OTDR measurement device according to any one of [1] to [6] above.

[8] A predetermined optical transmission line (100) including one or more optical fibers (101, 102) and a patch cord (105) is used as an object, and an optical pulse is sent to the proximal end (105a) of the patch cord, An OTDR measurement method for measuring the state of the optical transmission line by observing the return light from the optical fiber at the proximal end side of the patch cord,
a step of detecting, as an event, each phenomenon that occurs according to the configuration and state of the optical transmission line, based on the observation state of the time-series level change of the returned light;
determining the theoretical value of the optical fiber length of the patch cord as the cord length;
a step of automatically determining and correcting an event false detection that occurs in detecting the event in relation to the code length;
A method for measuring an OTDR comprising

10 Optical Pulse Tester Main Body 20 Event Processing Device 21 Observation Data Recording Section 22 Event Detection Section 23 Event Data Holding Section 24 Event Correction Section 25 Parameter Holding Section 26 Event Correction Condition Table 26a, 26b, 26c, 26d, 26e Individual Condition 26f Processing Classification 27 Display unit 28 Operation input unit 30 OTDR measuring device 100 Optical cable 101, 102 Optical fiber 101a, 102a Fiber proximal end 101b, 102b Fiber distal end 103, 104 Optical connector 105 Patch cord CS1, CS2, CS3, CS4, CS5, CS6 , CS7, CS8 Case classification d Distance EV1, EV2, EV3 Event Lpc Patch cord length Ppc Reference position Rer Error range Rev-1, Rev-2, Rev-3 Event range t Time TB2 Correction processing table w1, w2, w3 Event response Waveform Wo Returned light intensity waveform

Claims (8)

A predetermined optical transmission line (100) including one or more optical fibers (101, 102) and a patch cord (105) is used as a test object, an optical pulse is sent to the proximal end (105a) of the patch cord, and the optical fiber is An OTDR measuring device (30) for measuring the state of the optical transmission line by observing the return light from the near end side of the patch cord,
an event detection unit (22) for detecting, as an event, each event that occurs according to the configuration and state of the optical transmission line based on the observation state of the time-series level change of the returned light;
a parameter holding unit (25) holding a patch cord length (Lpc), which is the theoretical value of the optical fiber length of the patch cord;
Based on the patch cord length (Lpc) held in the parameter holding unit, the position of the boundary corresponding to the fiber near end (101a) of the optical fiber to which the far end (105b) of the patch cord is connected is determined. , determined as the reference position (Ppc) on the return light intensity waveform Wo,
determining the error range (Rer) of the reference position based on the correlation coefficient (Cc) that represents the inherent characteristics of the patch cord;
An event correction unit (24) for automatically judging erroneous event detection occurring in the event detection unit in relation to the patch cord length based on the reference position and the error range , and correcting the event judged to be erroneous detection. When,
An OTDR measuring device comprising: The event correction unit
At least one of each event range, the start point of each event, and the end point of each event detected by the event detection unit is compared with the reference position or the error range, and a process according to the result is performed.
The OTDR measuring device according to claim 1. The event correction unit
A condition table pre-holding information representing the correspondence relationship between conditions to be compared and types of processing to be executed for each of the plurality of cases (CS1 to CS8) related to the patch cord length,
The OTDR measuring device according to claim 2. The event correction unit adds a specific event associated with the reference position when the start point of any event is not included in the error range.
The OTDR measuring device according to claim 2. When the position to add the specific event is within the range between the start point and the end point of any of the events, the event correction unit adjusts the position of the end point of the corresponding event from the reference position. moving forward one data point and adding said specific event;
The OTDR measuring device according to claim 4. The event correction unit, when the starting point of any of the events is included in the error range, selects the type of the event whose starting point is closest to the reference position as a specific event associated with the reference position. change to
The OTDR measuring device according to claim 2. A predetermined optical transmission line (100) including one or more optical fibers (101, 102) and a patch cord (105) is used as a test object, an optical pulse is sent to the proximal end (105a) of the patch cord, and the optical fiber is An OTDR measuring device (30) for measuring the state of the optical transmission line by observing the return light from the near end side of the patch cord,
an event detection unit (22) for detecting, as an event, each event that occurs according to the configuration and state of the optical transmission line based on the observation state of the time-series level change of the returned light;
a cord length determination unit that determines the theoretical value of the optical fiber length of the patch cord as the cord length;
an event correction unit (24) for automatically judging erroneous event detection occurring in the event detection unit in relation to the code length and correcting the event judged as erroneous detection;
with
The event correction unit
determining a reference position (Ppc) corresponding to the code length and an error range (Rer) of the code length;
performing a process according to a result of comparing at least one of each event range detected by the event detection unit, the start point of each event, and the end point of each event with the reference position or the error range;
If the starting point of any event is included in the error range, changing the type of the event whose starting point is closest to the reference position to a specific event associated with the reference position;
OTDR measuring device. A predetermined optical transmission line (100) including one or more optical fibers (101, 102) and a patch cord (105) is used as a test object, an optical pulse is sent to the proximal end (105a) of the patch cord, and the optical fiber is An OTDR measurement method for measuring the state of the optical transmission line by observing the return light from the near end side of the patch cord,
a step of detecting, as an event, each phenomenon that occurs according to the configuration and state of the optical transmission line, based on the observation state of the time-series level change of the returned light;
holding a patch cord length (Lpc), which is a theoretical value of the optical fiber length of the patch cord;
Based on the held patch cord length (Lpc), the position of the boundary corresponding to the fiber near end (101a) of the optical fiber to which the far end (105b) of the patch cord is connected is determined from the intensity waveform of the returned light. Determined as a reference position (Ppc) on Wo,
determining the error range (Rer) of the reference position based on the correlation coefficient (Cc) that represents the inherent characteristics of the patch cord;
a step of automatically judging an event erroneous detection that occurs in detecting the event related to the patch cord length based on the reference position and the error range, and correcting the event that is judged to be an erroneous detection ;
A method for measuring an OTDR comprising

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