JP2006064399A - Breakage location detecting apparatus and fracture location detecting method of optical fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical fiber fracture location detecting apparatus and a method capable of simultaneously achieving both more compact size and lower costs than before and easily and highly accurately specifying the locations of a fracture point of optical fibers. <P>SOLUTION: The optical fiber fracture location detecting apparatus 100 is constituted of a modulated light irradiating part 102 for modulating projected light into modulated light BM1 of a prescribed frequency and irradiating the interior of an optical fiber 104 with the modulated light BM1; an optical coupler 106 capable of separating the modulated light BM1 of the modulated light irradiating part 102 from reflected light BM2, a measuring part 108 capable of measuring the distance to a fracture point BP on the basis of the phase difference between the separated modulated light BM1 and the reflected light BM2, and a display part 110 capable of displaying the distance to the fracture point BP. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical fiber break position detecting device and an optical fiber break position detecting method capable of specifying the position of a break point in an optical fiber.

  Conventionally, as an apparatus capable of irradiating projection light emitted from a light source into an optical fiber and identifying the position of the breaking point using reflected light reflected at the breaking point of the optical fiber, for example, shown in FIG. Such an optical fiber break position detector 10 called an OTDR (Optical Time Domain Reflectometer) is widely known (for example, refer to Patent Document 1).

  In this optical fiber break position detection device 10, the pulsed projection light emitted from the light source 12 is irradiated into the optical fiber 16 through the optical directional coupler 14 and reflected at the break point of the optical fiber 16. The returned reflected light is separated from the projection light by the optical directional coupler 14 and received by the light receiving unit 18. Then, the reflected light received by the light receiving unit 18 is amplified and shaped by the amplifier 20 or the signal processing device 22, and then the reflected light waveform is displayed on a display (not shown) of the display / recording device 24. Yes.

  FIG. 4 shows an example of the waveform of the reflected light measured by the optical fiber break position detecting device 10. In the figure, the vertical axis represents the logarithmically expressed light intensity (dB), and the horizontal axis represents the distance (km).

  Usually, the user of the optical fiber break position detection apparatus 10 analyzes the level change of the light intensity on the vertical axis, moves the cursor CS on the screen to a position BP that is considered to be the break point of the optical fiber 16, and then the horizontal axis. The position of the breaking point of the optical fiber 16 is specified by measuring the distance.

Japanese Patent Laid-Open No. 9-269248

  However, in such a conventionally known optical fiber break position detecting device 10, the user must specify the position of the break point of the optical fiber by analyzing the measurement waveform of the reflected light. In addition, there is a problem that an error is likely to occur in the measurement result depending on the user.

  In addition, since a large display for displaying the measurement waveform, a cursor CS for measuring the light intensity level, and operation buttons are necessary, it is difficult to reduce the size of the apparatus and increase the cost. There was also.

  The present invention has been made to solve such a problem, and while being able to realize a reduction in size and cost as compared with the conventional one, the position of the break point of the optical fiber can be easily and An object of the present invention is to provide an optical fiber break position detection apparatus and an optical fiber break position detection method that can be specified with high accuracy.

  The present invention provides an optical fiber break position detecting device that irradiates a projection light emitted from a light source into an optical fiber and can identify the position of the break point using reflected light reflected at the break point of the optical fiber. The modulated light is modulated into modulated light having a predetermined frequency, and the modulated light irradiating unit capable of irradiating the modulated light into the optical fiber, and the modulated light and the reflected light of the modulated light irradiating unit can be separated. An optical fiber coupler and a measuring unit capable of measuring a distance to the break point based on the phase difference between the separated modulated light and reflected light, and configured to solve the above problem It is.

  According to the present invention, a large display or the like conventionally required for displaying a measurement waveform of reflected light becomes unnecessary, and it is possible to realize a reduction in size and cost as compared with a conventional apparatus. Moreover, it is not necessary for the user of the apparatus to analyze the measurement waveform of the reflected light, and even a user who does not have specialized knowledge can easily and accurately specify the position of the break point of the optical fiber. Can do.

  Furthermore, if a display unit capable of displaying the distance to the breaking point is provided, the measurement result can be easily confirmed, and convenience can be improved.

  Moreover, if the frequency of the modulated light in the modulated light irradiation unit is set to 100 kHz to 200 kHz, it is possible to specify a disconnection position in a range of 500 m to 1 km. Accordingly, it is possible to cover a range of 500 m to 1 km, which is a general wiring interval of outdoor optical fibers applied to FTTH (Fiber To The Home), and to provide a device more suitable for user needs. It becomes.

  In the present invention, the optical fiber break position is detected by irradiating the projection light emitted from the light source into the optical fiber and using the reflected light reflected at the break point of the optical fiber. In the method, the projection light is modulated into modulated light having a predetermined frequency, the modulated light is irradiated into the optical fiber, and the distance to the break point is determined based on a phase difference between the modulated light and the reflected light. Measurement can also solve the same problem as described above.

  According to the optical fiber break position detection device and the optical fiber break position detection method according to the present invention, while being able to realize a reduction in size and cost as compared with the prior art, the position of the break point of the optical fiber can be easily and It can be specified with high accuracy.

  Hereinafter, an optical fiber break position detection device according to an example of an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 schematically shows the overall configuration of an optical fiber break position detection apparatus 10 according to an example of the present embodiment.

  The optical fiber break position detection device 100 modulates the projection light emitted from the light source 102A into modulated light BM1 having a predetermined frequency, and modulates the modulated light BM1 into the optical fiber 104. An optical fiber coupler 106 capable of separating the light BM1 and the reflected light BM2, and a measuring unit 108 capable of measuring the distance to the breaking point BP of the optical fiber 104 based on the phase difference between the separated modulated light BM1 and reflected light BM2. And a display unit 110 capable of displaying the distance to the breaking point BP. The optical fiber 104 to be detected is connected to the optical fiber break position detecting device 100 via a connector 103 such as an FC connector.

  The modulated light irradiation unit 102 is a light source 102A composed of an FP laser (wavelength 1.3 μm), a modulation unit 102B that modulates projection light emitted from the light source 102A into modulated light BM1 having a predetermined frequency, and the modulated light BM1. An isolator 102C that irradiates the fiber 104.

  The measuring unit 108 receives the modulated light BM1 separated by the optical fiber coupler 106, and is separated by the optical fiber coupler 106 and the first light receiving element 108A for converting the light intensity of the modulated light BM1 into an electrical signal. A second light receiving element 108B for receiving the reflected light BM2 and converting the light intensity of the reflected light BM2 into an electrical signal; a comparator 108C for measuring the phase difference between the modulated light BM1 and the reflected light BM2; The CPU 108D can calculate the distance to the break point BP of the optical fiber 104 based on the phase difference information from the comparator 108C. Note that photoelectric conversion elements such as photodiodes, photoconductors, and phototransistors can be applied as the first and second light receiving elements 108A and 108B.

  The display unit 110 is connected to the CPU 108D of the measurement unit 108, and the display unit 110 can display the distance to the breaking point BP of the optical fiber 104 calculated by the CPU 108D. As shown in the schematic perspective view of FIG. 2, an operation unit 112 including a plurality of (two in this example) operation buttons is provided beside the display unit 110.

  Next, the operation of the optical fiber break position detection device 100 will be described.

  When the start of measurement is instructed by pressing the operation button of the operation unit 112, the modulated light BM1 modulated to a predetermined frequency is emitted from the modulated light irradiation unit 102 and irradiated into the optical fiber 104 through the optical fiber coupler 106. The When the optical fiber 104 is disconnected, the modulated light BM1 is reflected at the breaking point BP of the optical fiber 104 and is incident on the optical fiber coupler 106 as reflected light BM2. The modulated light BM1 and the reflected light BM2 separated by the optical fiber coupler 106 are converted into electrical signals by the light receiving elements 108A and 108B, respectively, and then input to the comparator 108C. The CPU 108D that has acquired the phase difference information of the modulated light BM1 and the reflected light BM2 from the comparator 108C calculates the distance to the breaking point BP of the optical fiber 104 based on this phase difference information.

  For example, when the frequency of the modulated light BM1 is set to 1 MHz, the speed of light passing through the optical fiber 104 is 0.2 m / nanosecond, so the length of one period of the modulated light BM1 is 0.2 m / nano. Seconds × (1 ÷ 1 MHz) = 200 m / cycle. Therefore, if the reciprocating distance to the breaking point BP is within 200 m (one-way distance is 100 m), the distance to the breaking point BP (the travel distance of the reflected light BM2) is detected by detecting the phase difference between the modulated light BM1 and the reflected light BM2. ) Can be measured. The accuracy of the measurable distance is 200 m / 360 degrees = 0.6 m / degree when the phase difference detection precision by the comparator 108C is 1 degree.

  By the way, the general wiring interval of the outdoor optical fiber applied to FTTH is about 500 m to 1 km. Therefore, in order to be able to measure the distance 500 m to 1 km to the breaking point BP (1 km to 2 km in the reciprocating distance), it is preferable to set the frequency of the modulated light BM1 to 100 kHz to 200 kHz.

  Thus, the distance to the break point BP calculated by the CPU 108D is displayed on the display unit 110.

  According to the optical fiber break position detecting device 100 according to an example of the present embodiment, the modulated light is modulated into the modulated light BM1 having a predetermined frequency, and the modulated light irradiating unit 102 capable of irradiating the modulated light BM1 into the optical fiber 104; The optical fiber coupler 106 capable of separating the modulated light BM1 and the reflected light BM2 of the modulated light irradiation unit 102, and the distance to the breaking point BP is measured based on the phase difference between the separated modulated light BM1 and reflected light BM2. Therefore, a large display or the like, which has been necessary for displaying the measurement waveform of the reflected light, is unnecessary, and it is smaller and less expensive than the conventional apparatus. Can be realized. Moreover, it is not necessary for the user of the apparatus to analyze the measurement waveform of the reflected light, and even a user who does not have specialized knowledge can easily and accurately specify the position of the break point of the optical fiber. Can do.

  Moreover, since the optical fiber break position detecting device 100 includes the display unit 110 that can display the distance to the break point BP, the measurement result can be easily confirmed, and convenience is enhanced.

  Furthermore, since the frequency band of the modulated light BM1 in the modulated light irradiation unit 14 is 100 kHz to 200 kHz, it is possible to specify a disconnection position in the range of 500 m to 1 km. Therefore, the range of 500 m to 1 km, which is a general wiring interval of outdoor optical fibers applied to FTTH, can be covered, and a device more suitable for user needs can be provided.

  The optical fiber break position detecting device according to the present invention is not limited to the structure of the optical fiber break position detecting device 10 according to an example of the above embodiment. For example, the light source 22 has a wavelength of 1.3 μm. You may apply other than FP laser.

  Further, the frequency band of the modulated light BM1 is not limited to the numerical values shown in the above embodiment.

  Further, in the break position detecting device 10 described above, the display unit 110 is provided in order to improve convenience. However, the present invention is not limited to this, and the distance to the break point BP is set to an external display device or the like. You may comprise so that it may output.

  The optical fiber break position detection apparatus and the optical fiber break position detection method according to the present invention can be applied to inspection of a communication system in which an optical fiber is used as a communication medium.

1 is a schematic configuration diagram of an optical fiber break position detection device according to an example of an embodiment of the present invention. 1 is a schematic perspective view of the optical fiber break position detecting device in FIG. Schematic configuration diagram of a conventional optical fiber break position detector The figure which showed the example of a display of the measurement waveform of the reflected light by the optical fiber broken position detection apparatus in FIG.

Explanation of symbols

BM1 ... modulated light BM2 ... reflected light BP ... break point CS ... cursor 10, 100 ... optical fiber break position detector 12 ... light source 14 ... optical directional coupler 16, 104 ... optical fiber 18 ... light receiving unit 20 ... amplifier 22 ... Signal processing device 24 ... Display / recording device 102 ... Modulated light irradiation unit 102A ... Light source 102B ... Modulation unit 102C ... Isolator 103 ... Connector 106 ... Optical fiber coupler 108 ... Measuring unit 108A ... First light receiving element 108B ... Second light receiving element 108C ... Comparator 108D ... CPU
110: Display unit 112 ... Operation unit

Claims (4)

In an optical fiber break position detection device that irradiates projection light emitted from a light source into an optical fiber, and can identify the position of the break point using reflected light reflected at the break point of the optical fiber,
A light that can modulate the projection light into modulated light having a predetermined frequency and irradiate the modulated light into the optical fiber, and light that can separate the modulated light and the reflected light from the modulated light irradiation unit. An optical fiber breakage comprising: a fiber coupler; and a measuring unit capable of measuring a distance to the breakage point based on a phase difference between the separated modulated light and reflected light. Position detection device. In claim 1,
Furthermore, the display part which can display the distance to the said breaking point was provided. The optical fiber broken position detection apparatus characterized by the above-mentioned. In claim 1 or 2,
The frequency of the modulated light in the modulated light irradiation unit is set to 100 kHz to 200 kHz. In the optical fiber break position detecting method, the projection light emitted from the light source is irradiated into the optical fiber, and the position of the break point can be specified using the reflected light reflected at the break point of the optical fiber.
Modulating the projection light into modulated light having a predetermined frequency, irradiating the modulated light into the optical fiber, and measuring a distance to the break point based on a phase difference between the modulated light and the reflected light. An optical fiber break position detecting method characterized by the above.

Images