JP2016053542A - Optical pulse tester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To verify the validity of a detected event in an optical pulse tester that detects an event on the basis of a composite waveform.SOLUTION: The present invention is an optical pulse tester 100 for inputting an optical pulse to an optical fiber and measuring a temporal change in return light, the optical pulse tester comprising: a composite waveform generation unit 122 for setting an effective region from a near distance side for each of measured waveforms obtained by the optical pulses of different pulse widths, setting a composite line so that the effective region of the measured waveform obtained by the optical pulse of a shorter pulse width is prioritized, and joining each of the measured waveforms on the set composite line together and generating a composite waveform; an event detection unit 123 for detecting an event pertaining to the optical fiber on the basis of the composite waveform; and a display control unit 124 for displaying the composite waveform and the detected event.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an optical pulse tester, and more particularly to an optical pulse tester that measures return light with optical pulses having a plurality of pulse widths and synthesizes the obtained waveforms to perform event analysis.

  In an optical communication system that performs data communication using an optical signal, an optical fiber is used as a medium for transmitting the optical signal. Optical fiber length, connection loss, reflection, etc. need to be evaluated for laying optical fiber, relocating trouble, maintenance, etc. Optical pulse tester (OTDR: Optical Time Domain Reflectometer) ) Is used. The optical pulse tester is a device that performs display / analysis, etc., by measuring the power of light returning to the incident end by backscattered light or Fresnel reflection in a time domain by entering a light pulse into a measured optical fiber.

  Backscattered light, etc. is obtained by returning to the incident side with a delay time proportional to the distance from the reflection point, and drawing characteristic waveforms at the fusion point, connector connection point, branch point, bending point, cutting point, etc. From such optical power waveforms, events such as fusion points, connector connection points, branch points, bending points, and cutting points are detected and their distances are measured. The detected event is typically displayed as an icon, for example.

  The optical pulse incident on the optical fiber to be measured has a higher resolution as the pulse width is shorter. However, since the power of the light becomes smaller, it is easily affected by noise and cannot measure a long distance. For this reason, it is necessary to select a pulse width corresponding to the measurement distance during measurement.

  In recent years, measurement is performed with a plurality of pulse widths, waveforms obtained with the respective pulse widths are internally synthesized, and an event is detected based on the synthesized waveform. In waveform synthesis, the measurement distance is divided into multiple areas, and in areas where the distance is short, the waveform obtained with a light pulse with a short pulse width is used to improve resolution, and in areas where the distance is long, the pulse width is long. The waveform obtained with the light pulse is adopted so as not to be affected by noise.

JP-A-8-278222

  When measurement is performed with a plurality of pulse widths and an event is detected by combining waveforms obtained with the respective pulse widths, the detection result may differ depending on the combination method. For example, since a light pulse waveform with a long pulse width is used during synthesis, multiple adjacent events are detected as one event, or because a light pulse waveform with a short pulse width is used during synthesis, the waveform is disturbed by noise. It is a case where it is detected as an event.

  Therefore, if there is a mechanism that allows the user to verify whether the detected event is valid, the accuracy of event detection can be improved, which is beneficial.

  Therefore, the present invention is capable of verifying the validity of a detected event in an optical pulse tester that performs event detection by measuring return light with optical pulses having a plurality of pulse widths and synthesizing the obtained waveforms. The purpose is to.

In order to solve the above-mentioned problems, an optical pulse tester according to the present invention is an optical pulse tester for measuring a temporal change of return light by making an optical pulse incident on an optical fiber, which is obtained with optical pulses having different pulse widths. For each measured waveform, set the effective area from the short distance side, set the synthesis line so that the effective area of the measured waveform obtained with the light pulse with shorter pulse width is given priority, and set the synthesized A combined waveform generation unit that generates a combined waveform by connecting the respective measurement waveforms in a line; an event detection unit that detects an event related to the optical fiber based on the combined waveform; and the combined waveform and the detected event And a display control unit for displaying.
Here, when the composite waveform generation unit receives a change operation of the composite line from the user, the composite waveform generation unit can generate a composite waveform by connecting the respective measurement waveforms with the changed composite line.
At this time, it is desirable that the event detection unit re-detects the event every time a composite waveform is generated.
In addition, the display control unit can display the detected event in an icon format.
Further, the composite waveform generation unit can set an effective area of the measurement waveform based on the magnitude of the optical power of the measurement waveform.

  According to the present invention, it is possible to verify the validity of a detected event in an optical pulse tester that measures return light with optical pulses having a plurality of pulse widths and synthesizes the obtained waveforms to detect an event. become.

It is a block diagram which shows the structure of the optical pulse tester which concerns on this embodiment. It is a figure which shows the example of an external appearance of an operation reception part and a display part. It is a flowchart explaining the characteristic operation | movement of the optical pulse tester of this embodiment. It is a figure which shows the example of the measurement waveform for every different pulse width. It is a figure which shows the example of the effective area | region of the measurement waveform for every different pulse width. It is a figure which shows the example of the employ | adopted area | region of the measurement waveform for every different pulse width. It is a figure which shows the example of a synthetic | combination waveform. It is a figure which shows the example of the event detected from the synthetic | combination waveform. It is a figure which shows the example of icon display of an event. It is a figure which shows the comparative example of the measurement waveform for every different pulse width. It is a figure which shows the example of a change of a synthetic | combination line. It is a figure which shows the example of the event detected from the synthetic | combination waveform after a change.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of an optical pulse tester 100 according to the present embodiment. As shown in this figure, the optical pulse tester 100 is a device that performs a display / analysis etc. by measuring a light pulse incident on an optical fiber 200 to be measured and returning to the incident end in the time domain. A measurement processing unit 110, a connector 115, a control unit 120, an operation receiving unit 130, a display unit 140, and a storage unit 150.

  The measurement processing unit 110 includes a light emitting unit 111, an optical coupler 112, a light receiving unit 113, and a signal processing unit 114. The light emitting unit 111 can be configured by a laser diode or the like, and emits light at a predetermined interval by the pulse signal generated by the signal processing unit 114 to generate an optical pulse.

  The optical coupler 112 makes an optical pulse generated by light emission from the light emitting unit 111 incident on the optical fiber 200 to be measured via the connector 115, and makes return light from the optical fiber 200 incident via the connector 115. Lead to 113. The return light from the optical fiber 200 includes backscattered light due to Rayleigh scattering inside the optical fiber 200 and Fresnel reflected light generated at the connection point.

  The light receiving unit 113 can be configured by a photoelectric element or the like, and converts the return light into an electrical signal. The signal processing unit 114 generates an optical pulse to be supplied to the light emitting unit 111 and samples the electrical signal converted by the light receiving unit 113 at a timing synchronized with the pulse. The pulse width of the generated optical pulse is variable, and can be measured with a plurality of pulse widths. Since the return light from the optical fiber 200 is weak, the sampling by the signal processing unit 114 is repeated for a large number of optical pulses for each pulse width and averaged.

  The control unit 120 includes a measurement control unit 121, a waveform synthesis unit 122, an event detection unit 123, and a display control unit 124. The control unit 120 provides a user interface via the operation reception unit 130 and the display unit 140, and an optical pulse test. Various processes in the container 100 are controlled.

  The measurement control unit 121 controls the measurement operation in the optical pulse tester 100. Specifically, based on the measurement distance of the optical fiber 200, a plurality of pulse widths used for measurement are selected, the measurement for each pulse width is repeated a predetermined number of times, an averaging process is performed, and measurement for each pulse width is performed. Generate a waveform.

  The waveform synthesizer 122 determines an effective area for each measurement waveform for each pulse width, and synthesizes the waveform by setting a synthesis line for connecting the waveforms. At this time, a measurement waveform having a shorter pulse width is preferentially adopted in a short distance region. The composite line can be changed by a user operation.

  The event detection unit 123 detects events such as a fusion point, a connector connection point, a branch point, a bending point, and a cutting point from the composite waveform.

  The display control unit 124 performs display control of the composite waveform and the event detection result. On the composite waveform display screen, a composite line is displayed, and an operation for changing the composite line can be received from the user. Further, the detected event can be displayed as an icon on the event detection result display screen.

  The operation receiving unit 130 can be configured with buttons, switches, dial knobs, touch panels, and the like, and receives various operations related to the optical pulse test from the user. The display unit 140 can be configured by a liquid crystal display panel or the like, and displays a measurement waveform, an operation menu, and the like under the control of the display control unit 124. The storage unit 150 can be configured by a hard disk device, a semiconductor storage device, or the like, and records measurement data and the like under the control of the measurement control unit 121.

  FIG. 2 is a diagram illustrating an external appearance example of the operation receiving unit 130 and the display unit 140. In the present embodiment, the operation receiving unit 130 includes a power switch 131, a rotary knob 132, a scale key 133, a direction / enter key 134, a setup (SETUP) key 135, a real-time measurement (REAL TIME) key 136, and an averaged measurement (AVE). A key 137 and a function key 138 are provided.

  A characteristic operation of the optical pulse tester 100 configured as described above will be described with reference to the flowchart of FIG.

  Prior to execution of measurement, the optical pulse tester 100 selects a plurality of pulse widths used for measurement (S101). The pulse width to be selected may be arbitrarily selected by the user according to the distance of the optical fiber 200 to be measured, or may be automatically selected by the optical pulse tester 100 using a predetermined algorithm. . Further, the wavelength of the optical pulse, the sampling frequency, etc. are set as necessary.

  Of the plurality of selected pulse widths, a pulse width used for measurement is set (S102), and the measurement processing unit 112 performs measurement under the control of the measurement control unit 121 (S103). Measurement is repeated and averaged to obtain a waveform of the measurement result of the pulse width.

  The averaging measurement is repeated until all selected pulse widths are completed (S104). When the averaging measurement is completed for all the selected pulse widths (S104: Yes), a measurement waveform with each pulse width is obtained. FIG. 4 shows an example of each measurement waveform obtained when the selected pulse width is short, medium, or long. In this figure, the vertical axis indicates the power of the return light, and the horizontal axis indicates the distance corresponding to the delay time. In general, the shorter the pulse width, the higher the resolution. However, since the light power is small, it is easily affected by noise and cannot measure long distances.

  Next, the waveform synthesizer 122 determines an effective area for each measured waveform of the pulse width (S105). The effective area is an area that is less affected by noise or the like and can be regarded as a reasonable measurement result. For example, as shown in FIG. 5, the effective area can be determined from the short distance side to a position where the optical power falls below a predetermined reference value. However, the effective area may be determined using other criteria. In general, the shorter the pulse width, the shorter the effective area.

  When the effective area is determined for the measurement waveform of each pulse width, the waveform synthesis unit 122 performs waveform synthesis processing (S106). In the waveform synthesis process, the effective region of the measurement waveform having a shorter pulse width is preferentially adopted. This is because the measurement waveform with a shorter pulse width has a higher resolution.

  For this reason, as shown in FIG. 6, when the pulse width is short, all the effective areas are adopted areas, and in the pulse width: the area excluding the adopted area where the pulse width is short is adopted area. In the case of width: long, the area excluding the adoption area of the pulse width: short and the adoption area of the pulse width: medium from the effective area is the adoption area.

  Further, at the time of waveform synthesis, the waveform in the adopted area is moved up and down as necessary so that the synthesized waveforms are continuously connected. Specifically, the waveforms of the adopted areas having a shorter pulse width are sequentially connected with reference to the starting point of the adopted area of the measurement waveform having the longest pulse width.

  In the example of FIG. 6, the pulse width: medium waveform is moved upward so that the end point p2 of the pulse width: medium adoption region overlaps the start point p1 of the pulse width: long adoption region. Then, the pulse width: short waveform is moved upward so that the end point p4 of the pulse width: short adoption area overlaps the start point p3 of the adoption area in the pulse width: medium adoption area after movement. Thereby, a continuous composite waveform can be obtained. FIG. 7 shows an example of a combined waveform obtained by combining three waveforms. The connection position of the waveform of each pulse width is a composite line.

  When the composite waveform is generated, the event detection unit 123 detects an event based on the composite waveform (S107). Events such as fusion points, connector connection points, branch points, bend points, and cut points show characteristic waveforms, so events can be detected based on the composite waveform, and the detected event distance Can be identified. FIG. 8 shows an example of the detected event. Here, ten events e1 to e10 are detected.

  The display control unit 124 displays the composite waveform and the detected event on the display unit 140 as a measurement result (S108). As shown in FIG. 7, the combined waveform is displayed together with a combined line indicating the connection position of the waveform. Further, for example, as shown in FIG. 9, the detected event can be displayed by placing an icon display area 501 on the event display screen 500 and displaying an icon indicating the event content. In the icon display area 501, event icons and the positions of the events are schematically displayed.

  In addition, a list display area 502 is provided on the event display screen 500, and in addition to the distance and type for each event, detailed information regarding each event such as connection loss and section refractive index is displayed as a list.

  The user can determine whether the detection result of the event is valid by comparing the composite waveform with the event detection result.

  Furthermore, the display control unit 124 can also display an image in which the respective waveforms are superimposed on the display unit 140 in order to compare the waveforms of the respective pulse widths. FIG. 10A shows an example in which three measurement waveforms having different pulse widths are displayed in an overlapping manner, and FIG. 10B shows that the waveforms are moved up and down in order to match the connection points in the synthesis line. It is an example when displayed.

  By displaying an image in which waveforms having respective pulse widths are superimposed, the user can determine whether the waveform synthesis by the synthesis line is appropriate. Furthermore, in the optical pulse tester 100 of the present embodiment, the user can change the synthesis line. The composition line can be changed, for example, by operating the direction / enter key 134 to move the composition line in the distance direction.

  When an operation for changing the composite line is received from the user (S109: Yes), a waveform of each pulse width is combined with the changed composite line (S106). At the time of synthesis, the adoption area of the measurement waveform of each pulse width is changed so that the changed synthesis line becomes the boundary of each measurement waveform, and the pulse width is changed so that the synthesized waveform is continuous. Move the shorter waveform up or down. The point that the measurement waveform having a shorter pulse width is closer to the short distance side is the same after the change operation.

  FIG. 11 shows an example of a composite waveform connected by the changed composite line. The example of this figure is a case where the connection position of pulse width: short and pulse width: medium is moved to the short distance side. This is, for example, an operation performed when the user determines that the peak waveform at the point A (FIGS. 4 and 7) that appears only in the measurement waveform having a pulse width: short is noise. As a result of this operation, the area where the waveform having the pulse width: medium was adopted became longer on the short distance side, and the mountain-shaped waveform that appeared at point A disappeared from the synthesized waveform.

  When the composite waveform is generated with the changed composite line, the event detection unit 123 detects an event based on the newly generated composite waveform (S107), and the display control unit 124 displays the detection result event and the composite waveform. (S108). For this reason, the event detection result after changing the combined line can be confirmed immediately, and the validity can be efficiently judged.

  FIG. 12 shows an example of an event detected based on a new composite waveform. As shown in this figure, the event e5 detected in FIG. 8 is not detected, and the judgment result of the user can be easily reflected in the event detection result of the optical pulse tester 100.

  The change of the composite line by the user can be repeated many times, and the composite waveform can be displayed and the event detection result can be displayed each time. Thus, since the validity of the detected event can be verified, a more accurate measurement result and detection result can be obtained. Further, a function of outputting and printing a composite waveform, an event, and the like whose validity has been verified in a predetermined report format may be added. Thereby, for example, it becomes possible to easily create work reports such as laying optical fibers, relocating troubles, and maintenance.

DESCRIPTION OF SYMBOLS 100 ... Optical pulse tester, 110 ... Measurement processing part, 111 ... Light emission part, 112 ... Optical coupler, 112 ... Measurement processing part, 113 ... Light receiving part, 114 ... Signal processing part, 115 ... Connector, 120 ... Control part, 121 ... Measurement control unit 122 ... Waveform synthesis unit 123 ... Event detection unit 124 ... Display control unit 130 ... Operation reception unit 140 ... Display unit 150 ... Storage unit 200 ... Optical fiber

Claims (5)

An optical pulse tester for measuring a temporal change of return light by inputting an optical pulse into an optical fiber,
For each measurement waveform obtained with an optical pulse with a different pulse width, an effective area is set from the short distance side, and the effective area of the measurement waveform obtained with an optical pulse with a shorter pulse width is given priority. A combined waveform generation unit that generates a combined waveform by connecting the respective measured waveforms on the set combined line;
An event detector for detecting an event related to the optical fiber based on the combined waveform;
A display controller for displaying the synthesized waveform and the detected event;
An optical pulse tester comprising:   2. The light according to claim 1, wherein the composite waveform generation unit generates a composite waveform by connecting the respective measurement waveforms in the changed composite line when receiving a change operation of the composite line from a user. Pulse tester.   The optical pulse tester according to claim 2, wherein the event detection unit redetects an event every time a composite waveform is generated.   The optical pulse tester according to claim 1, wherein the display control unit displays the detected event in an icon format.   5. The optical pulse tester according to claim 1, wherein the combined waveform generation unit sets an effective region of the measurement waveform based on the magnitude of the optical power of the measurement waveform.