JP5410463B2 - Optical pulse tester event detection method and apparatus, and optical pulse test apparatus - Google Patents

Description

  The present invention relates to an event detection function of an optical pulse tester that performs an OTDR (Optical Time Domain Reflectometry) measurement.

  In recent years, the broadband environment has shifted from an ADSL (Asymmetric Digital Subscriber Line) to an optical fiber in order to support higher speed and larger capacity. Most of FTTH (Fiber To The Home) currently has a PON (Passive Optical Network) configuration that has a cost merit at the time of installation. FIG. 10 shows an example of a PON configuration and an OTDR waveform. The PON can accommodate a large number of subscriber homes 52-1 to 52-N with a single optical fiber up to the splitter 53, so that the laying cost can be suppressed, but compared with the conventional SS (Single Star) method. The difficulty of maintenance is a problem.

  When the optical pulse test is performed from the station 51 side, normal maintenance can be performed up to the splitter 53, but the subscriber homes 52-1 to 52-N are branched from the splitter 53. OTDR signals overlap. This makes it difficult to monitor PON from the station 51 side. Further, since a loss corresponding to the number of branches occurs in the splitter 53, better performance is required for the optical pulse tester.

  A change point of the measurement waveform is extracted, it is determined whether or not the point is an event that exceeds a set threshold value, and is detected as an event. In this case, when there is no change point in the measurement waveform (because the receiver limits the band, the change is less than that band), it is difficult to detect the event. Specifically, when there is a large loss, it is difficult to detect a loss event immediately after that or a reflection point shorter than the dead zone.

  For example, at the outlet of the splitter 53, troubles of connector connection or fusion connection may occur. In this case, a large loss occurs in the splitter 53 depending on the number of branches. Therefore, as shown in the OTDR waveform at the distance D2, the loss of the connector connection or fusion connection trouble occurs depending on the number of branches below the dead zone. Will overlap. For this reason, it is difficult to detect a trouble of connector connection or fusion connection.

  Further, there are cases where the distance from the splitter 53 is close to each other, such as the subscriber home 52-2 and the subscriber home 52-3. In this case, the Fresnel reflections at the subscriber premises 52-2 and the subscriber premises 52-3 overlap each other below the dead zone as shown by the OTDR waveforms at the distance D3 and the distance D4. For this reason, it is difficult to detect the Fresnel reflection of the subscriber's house 52-3.

WO2005 / 003714

  An object of the present invention is to detect the presence of an event even when the event occurs in a dead zone or lower.

  In order to achieve the above object, the present invention calculates a predicted waveform to be measured by an optical pulse tester when an event is measured using an apparatus waveform that is a characteristic of the optical pulse tester. An event is detected by comparing the measured waveform with an actual measured waveform.

  Specifically, in the optical pulse tester event detection method of the present invention, the change point of the OTDR waveform of the measurement target (hereinafter referred to as a measurement waveform) measured by the optical pulse tester that measures the OTDR waveform is used. Detecting and generating an OTDR waveform (hereinafter referred to as an ideal waveform) when loss or reflection occurs at the detected distance, and predicting loss or reflection included in the measurement waveform (S101) And the loss or reflection predicted by the event prediction procedure using the OTDR waveform (hereinafter referred to as a device waveform) measured by the optical pulse tester when there is no loss and reflection. OTDR waveform prediction procedure (S102) for calculating an OTDR waveform (hereinafter referred to as a predicted waveform) when the measurement is performed, and the measurement waveform and the OTDR waveform prediction procedure. A difference calculating step of generating a differential waveform seeking differences in the distances between the issued the estimated waveform (S103), in sequence.

  By executing the event prediction procedure (S101) and the OTDR waveform prediction procedure (S102), a predicted waveform to be measured by the optical pulse tester when the predicted event is measured can be calculated. By executing the difference calculation procedure (S103), it is possible to detect that an event has occurred in addition to the predicted event. Therefore, the optical pulse tester event detection method of the present invention can detect the presence of an event even when the event occurs in the dead zone or lower.

In the optical pulse tester event detection method of the present invention, an event addition determination procedure (S104) for determining whether the difference waveform generated in the difference calculation procedure includes a loss or a reflection is performed after the difference calculation procedure. In addition, when it is determined that it is included in the event addition determination procedure, the process proceeds to the event prediction procedure, and a new loss or reflection corresponding to the difference waveform is added to the ideal waveform in the event prediction procedure. An ideal waveform may be generated, and the OTDR waveform prediction procedure and the difference calculation procedure may be further repeated using the new ideal waveform.
Since the event addition determination procedure is included, an event other than the predicted event can be detected. Thereafter, by further repeating the event prediction procedure, the OTDR waveform prediction procedure, and the difference calculation procedure, an event below the dead zone can be detected.

In the optical pulse tester event detection method of the present invention, an OTDR waveform is measured using the optical pulse tester in a state where the measurement target is not connected to the optical pulse tester, and an OTDR waveform obtained by the measurement is obtained. A device waveform storage procedure (S105) for storing the device waveform may be further included before the event prediction procedure.
Since the apparatus waveform storing procedure (S105) is provided, the apparatus waveform of each optical pulse tester can be updated. For this reason, the predicted waveform of an arbitrary optical pulse tester can be calculated.

  In the optical pulse tester event detection method of the present invention, in the OTDR waveform prediction procedure, the predicted waveform is calculated by performing a convolution operation of the device waveform on the ideal waveform generated in the event prediction procedure. Also good.

  Specifically, the program of the present invention includes the event prediction procedure, the OTDR waveform prediction procedure and the difference calculation procedure, or the event prediction procedure and the OTDR waveform prediction procedure in the optical pulse tester event detection method of the present invention. , The difference calculation procedure and the event addition determination procedure, or the device waveform storage procedure, the event prediction procedure, the OTDR waveform prediction procedure and the difference calculation procedure, or the device waveform storage procedure, the event prediction procedure, Causes the computer to execute an OTDR waveform prediction procedure, the difference calculation procedure, and the event addition determination procedure.

  Specifically, the optical pulse tester event detection device of the present invention has a change point of an OTDR waveform (hereinafter referred to as a measurement waveform) of a measurement target measured by an optical pulse tester that measures an OTDR waveform. A fiber state estimation unit (11) that generates an OTDR waveform (hereinafter referred to as an ideal waveform) when a loss or reflection occurs at the detected distance and predicts the loss or reflection included in the measurement waveform. ) And an OTDR waveform (hereinafter referred to as an apparatus waveform) measured by the optical pulse tester when there is no loss or reflection, the loss or reflection predicted by the fiber state estimation unit is determined as the optical pulse. An OTDR waveform prediction unit (12) for calculating an OTDR waveform (hereinafter referred to as a predicted waveform) measured by the tester, and a difference in each distance between the measured waveform and the predicted waveform It comprises a difference calculation unit (13) for generating a differential waveform seeking.

  By providing the fiber state estimation unit (11) and the OTDR waveform prediction unit (12), it is possible to calculate a predicted waveform to be measured by the optical pulse tester when the predicted event is measured. By providing the difference calculation unit (13), it is possible to detect that an event has occurred in addition to the predicted event. Therefore, the optical pulse tester event detection device of the present invention can detect the presence of an event even when the event occurs below the dead zone.

In the optical pulse tester event detection device of the present invention, it is determined whether or not the difference waveform generated by the difference calculation unit includes loss or reflection, and when the difference waveform further includes loss or reflection An event addition determination unit (14) that outputs the difference waveform to the fiber state estimation unit is further provided, and the fiber state estimation unit further adds a loss or reflection corresponding to the difference waveform to the ideal waveform. An ideal waveform may be generated and the new ideal waveform may be output to the OTDR waveform prediction unit.
Since the event addition determination unit is provided, an event other than the predicted event can be detected. After that, a new ideal waveform is further generated by the fiber state estimation unit, so that an event below the dead zone can be detected.

  In the optical pulse tester event detection device of the present invention, the OTDR waveform prediction unit calculates the predicted waveform by performing a convolution operation of the device waveform on the ideal waveform generated by the fiber state estimation unit. May be.

Specifically, an optical pulse test apparatus according to the present invention includes the optical pulse tester event detection apparatus according to the present invention and the optical pulse tester that measures an OTDR waveform.
Since the optical pulse test apparatus according to the present invention includes the optical pulse tester event detection apparatus according to the present invention, even when an event occurs below the dead zone, it can be detected that there is an event.

  The above inventions can be combined as much as possible.

  According to the present invention, even when an event occurs below the dead zone, it can be detected that there is an event.

An example of the optical pulse test apparatus which concerns on this embodiment is shown. An example of the optical pulse tester event detection method which concerns on this embodiment is shown. An example of a device waveform is shown. It is an example of the state of the created object 100 to be measured. An example of a measurement waveform of the measurement object 100 in the optical pulse tester 10 is shown. An example of an ideal waveform is shown. It is an example of a prediction waveform and a measurement waveform, a solid line shows a prediction waveform and a broken line shows a measurement waveform. An example of the difference waveform of a measurement waveform and a prediction waveform is shown. An example of the new ideal waveform produced | generated using the difference waveform is shown. An example of a PON configuration and an OTDR waveform is shown.

  Embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments described below are examples of the present invention, and the present invention is not limited to the following embodiments. In the present specification and drawings, the same reference numerals denote the same components.

  FIG. 1 shows an example of an optical pulse test apparatus according to this embodiment. The optical pulse test apparatus according to the present embodiment includes an optical pulse tester 10 and an optical pulse tester event detection apparatus 20. The optical pulse tester 10 measures the OTDR waveform by outputting an optical pulse to the measurement object 100 and observing the return light. The measurement object 100 is, for example, an optical fiber or a PON.

  The optical pulse tester event detection device 20 detects loss or reflection in the measurement target 100 using the measurement waveform of the optical pulse tester 10. For example, the optical pulse tester event detection device 20 includes a fiber state estimation unit 11, an OTDR waveform prediction unit 12, a difference calculation unit 13, an event addition determination unit 14, and a device waveform storage unit 15.

  FIG. 2 shows an example of an optical pulse tester event detection method according to the present embodiment. The optical pulse tester event detection method according to the present embodiment includes an apparatus waveform storage procedure S105, an event prediction procedure S101, an OTDR waveform prediction procedure S102, a difference calculation procedure S103, and an event addition determination procedure S104 in this order. .

  First, the apparatus waveform storage procedure S105 is performed. In the apparatus waveform storage procedure S105, the apparatus waveform storage unit 15 stores the apparatus waveform. The apparatus waveform is an OTDR waveform measured by the optical pulse tester 10 when there is no loss and no reflection. For example, the optical pulse tester 10 performs OTDR measurement in a state where the measurement target 100 is not connected to the optical pulse tester 10. Then, the optical pulse tester 10 outputs the OTDR waveform to the device waveform storage unit 15.

  FIG. 3 shows an example of the apparatus waveform. As shown in FIG. 3, even when the measurement target 100 is not connected, the optical pulse tester 10 measures a waveform unique to the apparatus. This device-specific waveform is referred to as a device waveform. This device waveform varies from device to device and also varies depending on the pulse width. For this reason, in apparatus waveform storage procedure S105, it is preferable to measure apparatus waveforms for various pulse widths usable in the optical pulse tester 10.

  Hereinafter, the optical pulse tester event detection device 20 and the optical pulse tester event detection method according to the present embodiment will be described using a specific example of the created measurement target 100. FIG. 4 is an example of the state of the created object 100 to be measured. In the created object 100 to be measured, a splitter (reference numeral 53 shown in FIG. 10) is disposed at a distance D1, a connection loss occurs at a distance D2 that is the exit of the splitter, and Fresnel from a subscriber's home is at distances D3 and D4. There is reflection.

  FIG. 5 shows an example of a measurement waveform of the measurement target 100 in the optical pulse tester 10. In the measurement waveform, loss is detected near the distances D1 and D2, and Fresnel reflection is detected near the distances D3 and D4.

  In the event prediction procedure S101, the fiber state estimation unit 11 detects a change point of the measurement waveform, and generates an OTDR waveform (hereinafter referred to as an ideal waveform) when loss or reflection occurs at the detected distance. Predict the loss or reflection contained in the measured waveform.

  When generating an ideal waveform, first, a change point of the measurement waveform and its event shown in FIG. 5 are detected. For example, in the region A1 up to the distance D1, the light intensity decreases monotonously, and the decrease width increases at the distance D1. Thereby, the loss at the distance D1 is detected. In the region A2, the light intensity monotonously decreases, the light intensity starts to increase at the distance D3, and a light intensity peak exceeding a certain intensity appears. Here, the constant intensity is a light intensity capable of distinguishing Fresnel reflection and noise. Thereby, Fresnel reflection at the distance D3 is detected. Then, an ideal waveform is generated using the detected loss at the distance D1 and Fresnel reflection at the distance D3. FIG. 6 shows an example of an ideal waveform.

The ideal waveform is created as follows, for example.
The straight line in the area A2 is extended to the distance D1, and the extended line and the change point at the distance D1 are connected by a straight line. At this time, a straight line in the region A2 is obtained using a least square approximation straight line. Then, the extension line of the straight line may intersect with the changing point at the distance D1.
Further, the straight line of the area A2 is extended to the longest distance not less than the distance D3, and a reflection of a predetermined line width and light intensity is added to the position of the distance D3. At this time, the peak level at the distance D3 is determined by multiplying the peak light intensity I3 at the distance D3 and the distance D4 of the measurement waveform by the constant C determined from the apparatus waveform. By doing so, an ideal waveform of the Fresnel reflection portion can be obtained. Here, the constant C is the number of points corresponding to the full width at half maximum of the pulse waveform of the device function.

In the OTDR waveform prediction procedure S102, the OTDR waveform prediction unit 12 uses the ideal waveform and the device waveform to measure the OTDR waveform (hereinafter, prediction) when the optical pulse tester 10 measures the loss or reflection predicted in the event prediction procedure S101. Calculated as a waveform). For example, the OTDR waveform prediction unit 12 calculates a predicted waveform by performing a convolution operation of the device waveform on the ideal waveform. Thereby, a predicted waveform as shown in FIG. 7 is calculated. Here, in the convolution calculation, for example, _assuming that the light intensity of the ideal waveform at the distance k is x _k and the device waveform at the distance k is h _k , the predicted waveform yn is expressed by the following equation.

  In the difference calculation procedure S103, the difference calculation unit 13 calculates a difference waveform between the measurement waveform and the predicted waveform. The difference waveform is obtained by obtaining a difference at each distance between the measured waveform and the predicted waveform. The difference in each distance is, for example, the difference between the light intensity of the measured waveform at the distance D2 and the light intensity of the predicted waveform at the distance D2.

  In the present embodiment, events occur not only at the distance D1 and the distance D3 but also at the distance D2 and the distance D4. For this reason, as shown in FIG. 7, a difference occurs between the light intensity of the measured waveform and the light intensity of the predicted waveform at the distance D2 and the distance D4. In this case, as shown in FIG. 8, events at the distance D2 and the distance D4 appear in the differential waveform.

  In the event addition determination procedure S104, the event addition determination unit 14 determines whether the difference waveform generated in the difference calculation procedure S103 includes loss or reflection. When it is determined that the difference waveform does not further include loss or reflection, the event addition determination unit 14 outputs that fact from the port P2.

  However, in the present embodiment, the differential waveform shown in FIG. 8 has a constant light intensity up to the distance D2, but the light intensity starts to increase at the distance D2, and a peak of the light intensity exceeding the constant intensity appears. For this reason, the event addition determination unit 14 detects Fresnel reflection at the distance D2. In the differential waveform shown in FIG. 8, the light intensity starts to increase at the distance D4, and a light intensity peak exceeding a certain intensity appears. For this reason, the event addition determination unit 14 detects Fresnel reflection at the distance D4. Therefore, the event addition determination unit 14 determines that the difference waveform includes loss or reflection.

  In this case, the event addition determination unit 14 outputs the waveform shown in FIG. 8 from the port P1 to the difference waveform to the fiber state estimation unit 11. And it transfers to event prediction procedure S101.

  In the event prediction procedure S101, an ideal waveform to which loss or reflection corresponding to the difference waveform is added is generated, and the OTDR waveform prediction procedure S102 and the difference calculation procedure S103 are further repeated. For example, an ideal waveform of Fresnel reflection at the distance D2 and Fresnel reflection at the distance D4 is generated using the differential waveform shown in FIG. 8, and the generated waveform is added to the previously generated ideal waveform shown in FIG. The new ideal waveform generated as a result is shown in FIG. Then, this new ideal waveform is output to the OTDR waveform prediction unit 12. Then, the above-described OTDR waveform prediction procedure S102, difference calculation procedure S103, and event addition determination procedure S104 are repeated.

  Since the ideal waveform shown in FIG. 9 includes the state of the created measurement target 100 shown in FIG. 4, it is determined in the event addition determination procedure S104 that the measurement waveform does not further include loss or reflection. Thereby, the optical pulse tester event detection method according to the present embodiment is completed.

  As described above, the optical pulse tester event detection device 20, the optical pulse test device including the same, and the optical pulse tester event detection method according to the present embodiment can detect events at the distance D2 and the distance D4. . Therefore, the optical pulse tester event detection device 20 and the optical pulse test device including the same according to the present embodiment can detect the presence of an event even when an event occurs below the dead zone.

  The apparatus waveform storage procedure S105 may be performed between the event prediction procedure S101 and the OTDR waveform prediction procedure S102. Further, the optical pulse tester event detection device 20 according to the present embodiment may be realized by causing a computer to execute the optical pulse tester event detection method according to the present embodiment.

  The present invention can be applied to the information communication industry.

10: Optical pulse tester 11: Fiber state estimation unit 12: OTDR waveform prediction unit 13: Difference calculation unit 14: Event addition determination unit 15: Device waveform storage unit 20: Optical pulse tester event detection device 51: Station 52- 1, 52-2, 52-3, 52-4, 52-5, 52-N: subscriber's house 53: splitter 100: object to be measured

Claims (9)

When an OTDR waveform measured by an optical pulse tester that measures an OTDR waveform is detected, a change point of the OTDR waveform (hereinafter referred to as a measurement waveform) is detected, and an OTDR when loss or reflection occurs at the detected distance An event prediction procedure (S101) for generating a waveform (hereinafter referred to as an ideal waveform) and predicting a loss or reflection included in the measurement waveform;
The optical pulse tester measures the loss or reflection predicted by the event prediction procedure using an OTDR waveform (hereinafter referred to as a device waveform) measured by the optical pulse tester when there is no loss or reflection. An OTDR waveform prediction procedure (S102) for calculating an OTDR waveform (hereinafter referred to as a predicted waveform) when
A difference calculation procedure (S103) for obtaining a difference waveform by obtaining a difference in each distance between the measured waveform and the predicted waveform calculated in the OTDR waveform prediction procedure;
An optical pulse tester event detection method comprising: An event addition determination procedure (S104) for determining whether a loss or reflection is included in the difference waveform generated in the difference calculation procedure further after the difference calculation procedure,
If it is determined that it is included in the event addition determination procedure, the process proceeds to the event prediction procedure, and a new ideal waveform is generated by adding loss or reflection corresponding to the differential waveform to the ideal waveform in the event prediction procedure. The optical pulse tester event detection method according to claim 1, wherein the OTDR waveform prediction procedure and the difference calculation procedure are further repeated using the new ideal waveform.   Device waveform storage procedure for measuring an OTDR waveform using the optical pulse tester without connecting the object to be measured to the optical pulse tester, and storing the OTDR waveform obtained by the measurement as the device waveform (S105) 3) The optical pulse tester event detection method according to claim 1 or 2, further comprising:   4. The predicted waveform is calculated by performing a convolution operation of the device waveform on the ideal waveform generated in the event prediction procedure in the OTDR waveform prediction procedure. An optical pulse tester event detection method according to claim 1.   The event prediction procedure, the OTDR waveform prediction procedure, the difference calculation procedure, the event addition determination procedure, and the device waveform storage procedure of the optical pulse tester event detection method according to claim 1 in a computer A program to be executed. When an OTDR waveform measured by an optical pulse tester that measures an OTDR waveform is detected, a change point of the OTDR waveform (hereinafter referred to as a measurement waveform) is detected, and an OTDR when loss or reflection occurs at the detected distance A fiber state estimator (11) that generates a waveform (hereinafter referred to as an ideal waveform) and predicts a loss or reflection included in the measured waveform;
The optical pulse tester uses the OTDR waveform measured by the optical pulse tester when there is no loss or reflection (hereinafter referred to as a device waveform) to calculate the loss or reflection predicted by the fiber state estimation unit. An OTDR waveform prediction unit (12) for calculating an OTDR waveform when measured (hereinafter referred to as a predicted waveform);
A difference calculation unit (13) for determining a difference in each distance between the measured waveform and the predicted waveform to generate a differential waveform;
An optical pulse tester event detector. It is determined whether or not the difference waveform generated by the difference calculation unit includes loss or reflection. If the difference waveform further includes loss or reflection, the difference waveform is output to the fiber state estimation unit. An event addition determination unit (14) is further provided,
The fiber state estimation unit further generates a new ideal waveform obtained by adding a loss or reflection corresponding to the differential waveform to the ideal waveform, and outputs the new ideal waveform to the OTDR waveform prediction unit. The optical pulse tester event detection device according to claim 6.   The said OTDR waveform prediction part calculates the said prediction waveform by performing the convolution calculation of the said apparatus waveform with respect to the said ideal waveform produced | generated by the said fiber state estimation part, The said prediction waveform is calculated. Optical pulse tester event detection device. The optical pulse tester event detection device according to any one of claims 6 to 8,
The optical pulse tester for measuring an OTDR waveform;
An optical pulse test apparatus provided.

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