CN114172567B - Method and device for positioning fault point in optical fiber - Google Patents
Method and device for positioning fault point in optical fiber Download PDFInfo
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- CN114172567B CN114172567B CN202010946092.8A CN202010946092A CN114172567B CN 114172567 B CN114172567 B CN 114172567B CN 202010946092 A CN202010946092 A CN 202010946092A CN 114172567 B CN114172567 B CN 114172567B
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/07—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems
- H04B10/075—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal
- H04B10/079—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal using measurements of the data signal
- H04B10/0791—Fault location on the transmission path
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- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M11/00—Testing of optical apparatus; Testing structures by optical methods not otherwise provided for
- G01M11/30—Testing of optical devices, constituted by fibre optics or optical waveguides
- G01M11/31—Testing of optical devices, constituted by fibre optics or optical waveguides with a light emitter and a light receiver being disposed at the same side of a fibre or waveguide end-face, e.g. reflectometers
- G01M11/3109—Reflectometers detecting the back-scattered light in the time-domain, e.g. OTDR
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
- G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
- G01S17/06—Systems determining position data of a target
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Abstract
The application provides a method and a device for positioning fault points in optical fibers, and belongs to the technical field of optical fiber sensing. The device comprises: determining a first optical fiber length between an input end and an optical fiber fault point; triggering a first knocking event at a first earth surface knocking point, and determining a second optical fiber length between the input end and the first earth surface knocking point; determining an axial position point of the earth surface according to the difference value between the length of the first optical fiber and the length of the second optical fiber; a plurality of second earth surface knocking points to be knocked along the axial direction of the vertical optical fiber are determined by taking the earth surface axial position point as the center; triggering a second knocking event at each second surface knocking point, and determining a surface position point corresponding to the fault point from a plurality of second surface knocking points to be knocked according to second scattered light power corresponding to the second knocking event. The ground surface position point corresponding to the fault point in the optical fiber is determined from the transverse dimension and the longitudinal dimension according to the optical power corresponding to the knocking event, so that the accuracy of locating the fault point is improved.
Description
Technical Field
The present disclosure relates to the field of optical fiber sensing technologies, and in particular, to a method and an apparatus for locating a fault point in an optical fiber.
Background
Currently, optical fiber communication is widely used due to advantages of long distance, high speed, large capacity and the like. The failure of the optical fiber circuit can cause communication interruption, thereby causing serious influence on life, work, enterprise production and the like. Therefore, how to quickly and accurately locate the fault point in the optical fiber line, and gain time for timely recovering communication is a problem to be solved.
In the related art, a fault point in an Optical fiber line is determined by OTDR (Optical Time-Domain Reflectometer, optical Time domain reflectometry). The process comprises the following steps: inputting laser at the input end of the optical fiber, obtaining the light intensity of the backward scattered light of the laser at different positions in the optical fiber, obtaining the attenuation information of the laser at different positions in the optical fiber, and determining the attenuation curve of the optical fiber according to the attenuation information; the attenuation curve comprises a plurality of position points and attenuation values corresponding to the position points. In response to a failure of the fiber optic line, determining a point in the attenuation curve at which the attenuation value increases abruptly as a failure point.
However, when the fault point is located by the OTDR technology, only the position point of the fault point on the optical fiber can be determined. Because the optical fibers in the optical fiber line are not all laid in a straight line, the position points of the fault points on the optical fibers are different from the ground surface position points corresponding to the fault points, namely, the optical fiber fault points on the optical fibers cannot coincide with the ground surface fault points on the ground surface, the positions of the ground surface fault points cannot be accurately determined through an OTDR technology, so that the fault points in the optical fiber line can be positioned only after large-area excavation is needed around the ground surface fault points, and the accuracy of positioning the fault points in the optical fiber line through the OTDR technology is low.
Disclosure of Invention
The embodiment of the application provides a method and a device for positioning a fault point in an optical fiber, which can improve the accuracy of positioning the fault point in an optical fiber circuit. The technical scheme is as follows:
in one aspect, the present application provides a method for locating a fault point in an optical fiber, where the method includes: inputting pulse laser at an input end of an optical fiber to be tested, and determining a first optical fiber length between the input end and an optical fiber fault point according to the pulse laser, wherein the optical fiber fault point is a position point of the fault point on the optical fiber;
determining a first earth surface knocking point to be knocked according to the optical fiber fault point;
triggering a first knocking event at the first earth surface knocking point, and determining the length of a second optical fiber between the input end and the first earth surface knocking point according to first scattered light power corresponding to the first knocking event;
determining an earth surface axial position point according to the difference value between the first optical fiber length and the second optical fiber length, wherein the earth surface axial position point is an earth surface position point corresponding to the fault point along the optical fiber axial direction;
a plurality of second earth surface knocking points to be knocked along the axial direction of the optical fiber are determined by taking the earth surface axial position point as the center;
Triggering a second knocking event at each second earth surface knocking point, determining a target earth surface knocking point from the plurality of second earth surface knocking points to be knocked according to second scattered light power corresponding to the second knocking event, and taking the target earth surface knocking point as an earth surface position point corresponding to the fault point.
In one possible implementation manner, in the process of laying the optical fiber, a plurality of optical fiber identifiers are arranged at the surface positions corresponding to the optical fiber along the axial direction of the optical fiber;
the determining a first earth surface knocking point to be knocked according to the optical fiber fault point comprises the following steps:
and acquiring the earth surface position point corresponding to the optical fiber fault point, determining an optical fiber mark nearest to the earth surface position point corresponding to the optical fiber fault point, and taking the position of the optical fiber mark as the first earth surface knocking point.
In another possible implementation manner, the determining the surface axial position point according to the difference between the first optical fiber length and the second optical fiber length includes:
when the difference value between the first optical fiber length and the second optical fiber length is zero, determining the first earth surface knocking point as an earth surface axial position point; or alternatively, the process may be performed,
When the difference value between the first optical fiber length and the second optical fiber length is not zero, a plurality of third surface knocking points to be knocked between the surface position points corresponding to the optical fiber fault points and the optical fiber identifiers are determined along the axial direction of the optical fibers;
triggering a third knocking event at each third earth surface knocking point, and determining a third optical fiber length between the input end and the third earth surface knocking point according to third scattered light power corresponding to the third knocking event;
and selecting the surface axial position point with the length of the first optical fiber being the same as that of the third optical fiber from the plurality of third surface knocking points to be knocked.
In another possible implementation manner, the determining, according to the first scattered light power corresponding to the first tapping event, the second optical fiber length between the input end and the first surface tapping point includes:
detecting scattered light power in the optical fiber in the process of triggering a first knocking event to obtain a first relation curve between detection time and the scattered light power;
according to the first relation curve, determining the scattered light power with the largest light power change as the first scattered light power corresponding to the first knocking event;
Determining a first detection time corresponding to the first scattered light power;
and determining a second optical fiber length between the input end and the first surface knocking point according to the first detection time.
In another possible implementation manner, the determining, according to the first detection time, a second optical fiber length between the input end and the first surface tapping point includes:
acquiring the emission time of the pulse laser, and determining the time difference between the first detection time and the emission time;
determining a second optical fiber length between the input end and the first surface knocking point according to the time difference through the following formula I;
equation one: τ 2 ＝2n g l 2 /c
Wherein l 2 Representing the second optical fiber length τ 2 Represents the time difference between the first detection time and the emission time, c represents the speed of light, n g Representing the refractive index of the optical fiber.
In another possible implementation manner, the determining, according to the second scattered light power corresponding to the second tapping event, a target surface tapping point from the plurality of second surface tapping points to be tapped includes:
detecting scattered light power in the optical fiber in the process of triggering a second knocking event to obtain a second relation curve between detection time and the scattered light power;
Determining the scattered light power with the largest light power change as second scattered light power corresponding to the second knocking event according to the second relation curve;
and selecting a target surface tapping point with the maximum second scattered light power from the plurality of second surface tapping points to be tapped.
In another possible implementation manner, the triggering a first tapping event at the first surface tapping point, and before determining the second optical fiber length between the input end and the first surface tapping point according to the first scattered light power corresponding to the first tapping event, the method further includes:
and adjusting the pulse width value in the pulse laser to a preset pulse width value.
In another possible implementation manner, the determining the first optical fiber length between the input end and the optical fiber fault point according to the pulse laser includes:
in the process of inputting the pulse laser, detecting the scattered light power in the optical fiber to obtain a third relation curve between the detection time and the scattered light power;
determining a breakpoint position of sudden reduction of scattered light power in the third relation curve according to the third relation curve;
and taking the breakpoint position as an optical fiber fault point, and determining the first optical fiber length between the input end and the optical fiber fault point.
In another aspect, the present application provides a device for locating a fault point in an optical fiber, the device comprising: the first determining module is used for inputting pulse laser at the input end of the optical fiber to be detected, determining the first optical fiber length between the input end and an optical fiber fault point according to the pulse laser, wherein the optical fiber fault point is a position point of the fault point on the optical fiber;
the second determining module is used for determining a first earth surface knocking point to be knocked according to the optical fiber fault point;
the third determining module is used for triggering a first knocking event at the first earth surface knocking point and determining the second optical fiber length between the input end and the first earth surface knocking point according to the first scattered light power corresponding to the first knocking event;
a fourth determining module, configured to determine a surface axial position point according to a difference between the first optical fiber length and the second optical fiber length, where the surface axial position point is a surface position point corresponding to the fault point along the optical fiber axial direction;
a fifth determining module, configured to determine a plurality of second surface tapping points to be tapped along a direction perpendicular to the axial direction of the optical fiber, with the surface axial position point as a center;
And a sixth determining module, configured to trigger a second tapping event at each second surface tapping point, determine a target surface tapping point from the plurality of second surface tapping points to be tapped according to second scattered light power corresponding to the second tapping event, and use the target surface tapping point as a surface location point corresponding to the fault point.
In one possible implementation manner, in the process of laying the optical fiber, a plurality of optical fiber identifiers are arranged at the surface positions corresponding to the optical fiber along the axial direction of the optical fiber;
the second determining module is configured to obtain a surface location point corresponding to the optical fiber fault point, determine an optical fiber identifier nearest to the surface location point corresponding to the optical fiber fault point, and take a location of the optical fiber identifier as the first surface knocking point.
In another possible implementation manner, the fourth determining module is configured to determine that the first surface tapping point is a surface axial position point when a difference between the first optical fiber length and the second optical fiber length is zero; or, the fourth determining module is configured to determine, along the axial direction of the optical fiber, a plurality of third surface tapping points to be tapped between the surface location points corresponding to the optical fiber fault points and the optical fiber identifiers when the difference between the lengths of the first optical fiber and the second optical fiber is not zero; triggering a third knocking event at each third earth surface knocking point, and determining a third optical fiber length between the input end and the third earth surface knocking point according to third scattered light power corresponding to the third knocking event; and selecting the surface axial position point with the length of the first optical fiber being the same as that of the third optical fiber from the plurality of third surface knocking points to be knocked.
In another possible implementation manner, the third determining module includes:
the detection unit is used for detecting scattered light power in the optical fiber in the process of triggering a first knocking event to obtain a first relation curve between detection time and the scattered light power;
the first determining unit is used for determining that the scattered light power with the largest light power change is the first scattered light power corresponding to the first knocking event according to the first relation curve;
a second determining unit, configured to determine a first detection time corresponding to the first scattered light power;
and the third determining unit is used for determining the second optical fiber length between the input end and the first surface knocking point according to the first detection time.
In another possible implementation manner, the third determining unit is configured to obtain an emission time of the pulse laser, and determine a time difference between the first detection time and the emission time; determining a second optical fiber length between the input end and the first surface knocking point according to the time difference through the following formula I;
equation one: τ 2 ＝2n g l 2 /c
Wherein l 2 Representing the second optical fiber length τ 2 Represents the time difference between the first detection time and the emission time, c represents the speed of light, n g Representing the refractive index of the optical fiber.
In another possible implementation manner, the sixth determining module is configured to detect the scattered light power in the optical fiber during the second knocking event to obtain a second relationship curve between the detection time and the scattered light power; determining the scattered light power with the largest light power change as second scattered light power corresponding to the second knocking event according to the second relation curve; and selecting a target surface tapping point with the maximum second scattered light power from the plurality of second surface tapping points to be tapped.
In another possible implementation, the apparatus further includes:
the adjusting module is used for adjusting the pulse width value in the pulse laser to a preset pulse width value.
In another possible implementation manner, the first determining module is configured to detect the scattered light power in the optical fiber during the process of inputting the pulse laser, so as to obtain a third relationship curve between the detection time and the scattered light power; determining a breakpoint position of sudden reduction of scattered light power in the third relation curve according to the third relation curve; and taking the breakpoint position as an optical fiber fault point, and determining the first optical fiber length between the input end and the optical fiber fault point.
The embodiment of the application provides a positioning method of a fault point in an optical fiber, which is characterized in that the fault point in the optical fiber is coarsely positioned to obtain a first earth surface knocking point, then the first knocking event is triggered at the first earth surface knocking point, the fault point is positioned in the axial dimension of the optical fiber to obtain an earth surface axial position point of the fault point, then the earth surface axial position point is taken as a center, a plurality of second earth surface knocking points perpendicular to the axial direction of the optical fiber are used for triggering a second knocking event, the fault point is positioned in the transverse dimension of the optical fiber, and finally the earth surface position point corresponding to the fault point is determined. Therefore, the method can position the fault point from the two dimensions of the axial dimension and the transverse dimension of the optical fiber based on the knocking event, so that the earth surface position point corresponding to the fault point is accurately positioned, and the accuracy of positioning the fault point in the optical fiber can be improved.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a flow chart of a method for locating a fault point in an optical fiber according to an embodiment of the present application;
fig. 2 is a schematic structural diagram of a laser fault locating device according to an embodiment of the present application;
fig. 3 is a block diagram of a fault point locating device in an optical fiber according to an embodiment of the present application.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the present application more apparent, the embodiments of the present application will be described in further detail below with reference to the accompanying drawings.
Fig. 1 is a flowchart of a method for locating a fault point in an optical fiber provided in the present application. In the embodiment of the application, a computer device is taken as an example of a laser fault locating device. Referring to fig. 1, the method includes:
101. the laser fault positioning device inputs pulse laser at the input end of the optical fiber to be tested, and determines the length of a first optical fiber between the input end and the optical fiber fault point according to the pulse laser, wherein the optical fiber fault point is the position point of the fault point on the optical fiber.
The pulse width value of the pulse laser is Tp, the time interval of pulse emission is T, and the frequency fs of pulse emission is 1/T.
Referring to fig. 2, a description will be given of a laser failure positioning apparatus including: the device comprises an optical emission module, an optical modulation module, a synchronous driving module, a loop module, an amplifying module, a filtering module, a detection module, a signal acquisition module and a signal processing module.
The synchronous driving module is respectively connected with the light modulation module and the signal acquisition module; the other ends of the light emitting module, the light modulation module and the loop module are sequentially connected; the other end of the loop module, the filtering module, the detection module, the signal acquisition module and the signal processing module are connected in sequence; the amplifying module is connected with the optical fiber to be tested.
The light emitting module is used for emitting laser pulses; the optical modulation module is used for adjusting the pulse width of the laser pulse; the synchronous driving module is used for synchronizing the emission time of the laser pulse and the acquisition time of the signal acquisition module; and the amplifying module is used for amplifying the scattered light power in the optical fiber to be detected.
The loop module is used for inputting pulse laser into the input end of the optical fiber to be tested and inputting scattered light power of the optical fiber to be tested into the filtering module; the filtering module is used for removing noise in the scattered light power; the detection module is used for detecting scattered light power in the optical fiber; the signal acquisition module is used for acquiring the scattered light power detected by the detection module; and the signal processing module is used for converting the scattered light power from an optical signal to an electric signal and determining the earth surface position point corresponding to the fault point in the optical fiber through the electric signal.
In one possible implementation, the step of determining, by the laser fault location device, the first fiber length between the input end and the fiber fault point according to the pulsed laser includes: the laser fault positioning equipment detects scattered light power in the optical fiber in the process of inputting pulse laser at the input end of the optical fiber to be detected, and a third relation curve between detection time and the scattered light power is obtained; determining the breakpoint position of the sudden decrease of the scattered light power in the third relation curve according to the third relation curve; and taking the breakpoint position as an optical fiber fault point, and determining the first optical fiber length between the input end and the optical fiber fault point according to the second detection time of the breakpoint position.
In one possible implementation manner, the step of determining the first optical fiber length between the input end and the optical fiber fault point by the laser fault positioning device according to the second detection time of the breakpoint position includes: the laser fault positioning device obtains second detection time of the breakpoint position and emission time of the pulse laser, and the time difference between the second detection time and the emission time is used for detecting the fault point position; determining the length of a first optical fiber between an input end and an optical fiber fault point through the following formula II;
formula II: τ 1 ＝2n g l 1 /c
Wherein l 1 Representing the first optical fiber length τ 1 Represents the time difference between the second detection time and the emission time, c represents the speed of light, n g Indicating the refractive index of the fiber.
Note that the scattered light power is backward rayleigh scattered light power. In the forward transmission process of the pulse laser along the optical fiber, backward Rayleigh scattering is generated in the optical fiber, and in the coherent length of the pulse laser, the backward Rayleigh scattering lights at different positions in the optical fiber are mutually overlapped. When the optical fiber does not fail, the refractive index of the optical fiber is unchanged, and the optical power of the backward Rayleigh scattered light is constant; when the optical fiber fails, the refractive index of the position of the failure point of the optical fiber changes, and the optical power scattered by backward Rayleigh changes. For example, the optical power of backward Rayleigh scattering decreases abruptly.
102. And the laser fault positioning equipment determines a first earth surface knocking point to be knocked according to the optical fiber fault point.
In the process of laying the optical fiber, a plurality of optical fiber identifiers are arranged at the surface positions corresponding to the optical fiber along the axial direction of the optical fiber; that is, the fiber identification is located at a surface location directly above the fiber. Alternatively, the optical fiber is identified as "where the optical fiber is laid".
In one possible implementation, the step includes: the laser fault positioning equipment determines the earth surface position point corresponding to the optical fiber fault point according to the optical fiber fault point and the first optical fiber length, determines the optical fiber mark nearest to the earth surface position point corresponding to the optical fiber fault point, and takes the position of the optical fiber mark as a first earth surface knocking point. The ground distance between the ground surface position point corresponding to the optical fiber fault point and the input end of the optical fiber is the first optical fiber length. For example, in the optical fiber, when the distance between the input end and the optical fiber fault point is 100m, the surface distance between the input end and the surface position point corresponding to the optical fiber fault point is 100m.
In one possible implementation, the laser fault location device stores the location of the fiber identifier corresponding to the fiber to be tested. The laser fault positioning equipment directly determines the optical fiber identifier nearest to the surface location point corresponding to the optical fiber fault point according to the stored position of the optical fiber identifier and the surface location point corresponding to the optical fiber fault point.
In another possible implementation, the measurement result is input to the laser fault location device by measuring a distance between a surface location point corresponding to the optical fiber fault point and at least one optical fiber identifier around the optical fiber fault point by a field tester. And the laser fault positioning equipment determines the optical fiber identifier nearest to the surface position point corresponding to the optical fiber fault point according to the measurement result.
103. Triggering a first knocking event at a first earth surface knocking point, and determining a second optical fiber length between the input end and the first earth surface knocking point by the laser fault positioning equipment according to first scattered light power corresponding to the first knocking event.
In one possible implementation, the first tapping event is triggered by applying pressure at a first surface tapping point. Alternatively, pressure is applied at the first surface tapping point by tapping the surface at the first surface tapping point. When the number of first tap events is multiple, the pressure of each tap needs to be kept the same. Alternatively, the first tapping event is triggered by a standard plumb falling at the same height.
The point to be described is that a first knocking event is triggered at a first earth surface knocking point, the ground of the first earth surface knocking point is deformed due to the pressure of the first knocking event, and then the optical fiber paved below the first earth surface knocking point is also deformed due to the stress. Due to the elasto-optical effect, the phase of the rayleigh scattered light of the laser pulse at the deformation of the optical fiber changes, resulting in a change in the optical power of the rayleigh scattered light.
In one possible implementation manner, the step of determining, by the laser fault location device, the second optical fiber length between the input end and the first surface tapping point according to the first scattered light power corresponding to the first tapping event includes: the laser fault positioning equipment detects scattered light power in the optical fiber in the process of triggering a first knocking event to obtain a first relation curve between detection time and the scattered light power; according to the first relation curve, determining the scattered light power with the largest light power change as first scattered light power corresponding to a first knocking event; and determining a first detection time corresponding to the first scattered light power, and determining a second optical fiber length between the input end and the first surface knocking point according to the first detection time.
In one possible implementation, the step of determining, by the laser fault location device, the second optical fiber length between the input end and the first surface tapping point according to the first detection time includes: the laser fault positioning equipment acquires the emission time of pulse laser and determines the time difference between the first detection time and the emission time; according to the time difference, determining the length of a second optical fiber between the input end and the first surface knocking point through the following formula I;
equation one: τ 2 ＝2n g l 2 /c
Wherein l 2 Representing the second optical fiber length τ 2 Represents the time difference between the first detection time and the emission time, c represents the speed of light, n g Indicating the refractive index of the fiber.
It should be noted that the spatial resolution of the laser fault localization apparatus for the length of the optical fiber is related to the pulse width value Tp of the laser pulse. When the laser pulse propagates in the optical fiber, the length of the optical fiber with the same laser pulse in the optical fiber is cT p /n g . Wherein c represents the speed of light, n g Indicating the refractive index of the fiber. Thus, the laser fault locating device will simultaneously receive a length cT p /2n g Rayleigh scattered optical power in an optical fiber, i.e. the spatial resolution of the laser fault localization apparatus to the length of the optical fiber is cT p /2n g . It can be seen that by reducing the pulse width value Tp of the laser pulse, the spatial resolution of the laser fault locating device can be reduced, and the locating precision of the laser fault locating device along the axial direction of the optical fiber can be improved.
Another point to be described is that decreasing the pulse width value of the laser pulse decreases the optical power of the laser pulse, which decreases the signal-to-noise ratio of the laser fault localization apparatus. In one possible implementation manner, the resolution of the laser fault locating device is adjustable through the light modulation module and the amplifying module, the resolution of the laser fault locating device is increased on the basis of reducing the signal-to-noise ratio of the optical power signal, and the accuracy of the earth surface position point corresponding to the locating fault point is improved. Optionally, the laser fault locating device increases the optical power of the laser pulse in a mode of amplifying in the same direction.
In one possible implementation manner, in order to improve the positioning accuracy of the laser fault positioning device, a first knocking event is triggered at a first earth surface knocking point, and before determining the length of a second optical fiber between the input end and the first earth surface knocking point according to the first scattered light power corresponding to the first knocking event, the laser fault positioning device adjusts a pulse width value in pulse laser to a preset pulse width value. Optionally, the preset pulse width value is less than 200ns, e.g., 20ns, 25ns, 30ns, etc. In the present application, the value of the preset pulse width value is not particularly limited, and may be set and changed as needed.
In one possible implementation, the laser fault locating device emits pulsed laser light through the light emitting module. Optionally, the light emitting module is a narrow linewidth laser.
104. And the laser fault positioning equipment determines an earth surface axial position point according to the difference value between the length of the first optical fiber and the length of the second optical fiber, wherein the earth surface axial position point is an earth surface position point corresponding to the fault point along the axial direction of the optical fiber.
It should be noted that, since the optical fibers in the optical fiber line are not all laid in a straight line, the first optical fiber length between the input end and the failure point of the optical fiber is longer than the surface distance between the input end and the failure point. Therefore, the earth surface position point corresponding to the fault point cannot be accurately positioned through the optical fiber fault point. In the step, a knocking event is triggered around the earth surface position point corresponding to the optical fiber fault point, so that the earth surface position point corresponding to the fault point is accurately positioned.
In one possible implementation manner, the step of determining, by the laser fault location device, the surface axial position point according to the difference between the first optical fiber length and the second optical fiber length is: when the difference between the first optical fiber length and the second optical fiber length is zero, the laser fault locating device determines that the first earth surface knocking point is an earth surface axial position point.
For example, the first fiber length between the input end and the fiber fault point is 100m, if the first knocking event is triggered at the fiber mark at the 90m position, the laser fault location device determines that the second fiber length between the input end and the first surface knocking point is 100m, the difference between the first fiber length and the second fiber length is zero, and the laser fault location device determines that the 90m position is the position of the fault point along the fiber axial direction.
In another possible implementation manner, the step of determining the surface axial position point by the laser fault location device according to the difference between the first optical fiber length and the second optical fiber length is: when the difference value between the first optical fiber length and the second optical fiber length is not zero, the laser fault positioning equipment determines a plurality of third ground surface knocking points to be knocked between the ground surface position point corresponding to the optical fiber fault point and the optical fiber mark along the axial direction of the optical fiber; triggering a third knocking event at each third earth surface knocking point, and determining a third optical fiber length between the input end and the third earth surface knocking point according to third scattered light power corresponding to the third knocking event; and selecting a surface axial position point with the length of the first optical fiber being the same as that of the third optical fiber from a plurality of third surface knocking points to be knocked. Optionally, a third tapping event is triggered by a standard plumb falling at the same height.
In this step, the method for determining the length of the third optical fiber between the input end and the third surface tapping point by the laser fault location device according to the third scattered light power corresponding to the third tapping event is the same as the method for determining the length of the second optical fiber between the input end and the first surface tapping point by the laser fault location device according to the first scattered light power corresponding to the first tapping event in step 103, and will not be described herein.
The point to be noted is that the plurality of third earth surface knocking points are uniformly distributed between the earth surface position points corresponding to the optical fiber fault points and the optical fiber identifications. Wherein, the distance interval between the plurality of third earth's surface strike points is greater than the spatial resolution of the laser fault location device. In the embodiment of the present application, the distance interval between the third surface tapping points is not particularly limited, and may be set and changed as required. Alternatively, the distance spacing between the plurality of third surface tapping points may be any value between 10m-30m, e.g., 20m, 22m, 25m, etc.
105. The laser fault positioning device is used for determining a plurality of second earth surface knocking points to be knocked along the axial direction of the vertical optical fiber by taking the earth surface axial position point as the center.
In one possible implementation, the step includes: the laser fault positioning equipment takes the axial position point of the earth surface as the center, and a plurality of second earth surface knocking points to be knocked are uniformly arranged along the axial direction of the vertical optical fiber.
Wherein, the distance interval between the plurality of second earth's surface strike points is greater than the spatial resolution of the laser fault location device. In the embodiment of the present application, the distance interval between the second surface tapping points is not particularly limited, and may be set and changed as required. Alternatively, the distance spacing between the plurality of second surface tapping points may be any value between 10m-30m, e.g., 20m, 22m, 25m, etc.
106. Triggering a second knocking event at each second earth surface knocking point, and determining a target earth surface knocking point from a plurality of second earth surface knocking points to be knocked according to second scattered light power corresponding to the second knocking event by the laser fault positioning equipment, wherein the target earth surface knocking point is taken as an earth surface position point corresponding to the fault point.
In one possible implementation manner, the step of determining, by the laser fault location device, the target surface tapping point from the plurality of second surface tapping points to be tapped according to the second scattered light power corresponding to the second tapping event includes: in the process of triggering a second knocking event, the laser fault positioning equipment detects scattered light power in the optical fiber to obtain a second relation curve between detection time and the scattered light power; according to the second relation curve, determining the scattered light power with the largest light power change as second scattered light power corresponding to a second knocking event; and selecting a target surface tapping point with the maximum second scattered light power from a plurality of second surface tapping points to be tapped. Optionally, a third tapping event is triggered by a standard plumb falling at the same height.
It should be noted that, triggering the second knocking event at each second earth surface knocking point, the ground of each second earth surface knocking point is deformed due to the pressure of the second knocking event, and the degree of deformation of the optical fiber caused by each second earth surface knocking point is different due to the different lateral distance between each second earth surface knocking point and the optical fiber, and the smaller the lateral distance between the second earth surface knocking point and the optical fiber is, the more the deformation amount of deformation of the optical fiber is, and the larger the change of the rayleigh scattering optical power corresponding to the knocking event is.
In the embodiment of the application, after the earth surface position points corresponding to the fault points along the axial direction of the optical fiber are determined, the target earth surface knocking point closest to the optical fiber is determined from a plurality of second earth surface knocking points along the axial direction of the perpendicular optical fiber through the second scattered light power corresponding to each second position point, and the earth surface position points corresponding to the fault points are positioned from the two dimensions of the transverse direction and the axial direction of the optical fiber, so that the accuracy of positioning the fault points is improved.
Another point to be noted is that the pulsed laser light is backscattered in an optical fiber, which includes a plurality of scattering centers for rayleigh scattering. The following description will take an example in which the pulse width value of the pulse laser is Tp, the time interval of pulse emission is T, and the frequency fs of pulse emission is 1/T.
Wherein the backward Rayleigh scattering amplitude in the fiber is expressed as the following equation (1);
formula (1):
wherein a is i Represents the amplitude of the ith scattering center, τ i Represents the time delay of the ith scattering center, N represents the number of scattering centers in the fiber, α represents the attenuation constant of the fiber, when
Rectangular function->
Otherwise, go (L)>
Wherein the backward Rayleigh scattered light power in the optical fiber is expressed as the following formula (2);
formula (2):
wherein phi is ij ＝2πf(τ i -τ j )，a i Represents the amplitude of the ith scattering center, τ i Represents the time delay of the ith scattering center, a j Represents the amplitude of the jth scattering center, τ j Represents the time delay of the jth scattering center, N represents the number of scattering centers in the fiber, and α represents the attenuation constant of the fiber when
Rectangular function->
Otherwise the first set of parameters is selected,
when->
Rectangular function->
Otherwise, go (L)>
Wherein p is a (t) the fundamental optical power, p, at the position in the fiber when the same pulse passes b And (t) is an optical power added value at the position after the optical powers of the plurality of scattering centers interfere when the same pulse passes. When the deformation amount of the deformation of the optical fiber is larger, the superposition value of the optical power at the position is larger, and the change of the Rayleigh scattering optical power corresponding to the knocking event is larger.
The method for positioning the fault point in the optical fiber can be used for detecting and positioning the fault point in the optical fiber when the optical fiber fails, and can also be used for monitoring the fault point in the optical fiber in real time when the optical fiber normally communicates.
The embodiment of the application provides a positioning method of a fault point in an optical fiber, which is characterized in that the fault point in the optical fiber is coarsely positioned to obtain a first earth surface knocking point, then the first knocking event is triggered at the first earth surface knocking point, the fault point is positioned in the axial dimension of the optical fiber to obtain an earth surface axial position point of the fault point, then the earth surface axial position point is taken as a center, a plurality of second earth surface knocking points perpendicular to the axial direction of the optical fiber are used for triggering a second knocking event, the fault point is positioned in the transverse dimension of the optical fiber, and finally the earth surface position point corresponding to the fault point is determined. Therefore, the method can position the fault point from the two dimensions of the axial dimension and the transverse dimension of the optical fiber based on the knocking event, so that the earth surface position point corresponding to the fault point is accurately positioned, and the accuracy of positioning the fault point in the optical fiber can be improved.
Fig. 3 is a schematic diagram of a positioning device for fault points in an optical fiber provided in the present application. Referring to fig. 3, the apparatus includes:
the first determining module 301 is configured to input a pulse laser at an input end of an optical fiber to be tested, determine a first optical fiber length between the input end and an optical fiber fault point according to the pulse laser, where the optical fiber fault point is a position point of the fault point on the optical fiber;
a second determining module 302, configured to determine a first surface tapping point to be tapped according to the optical fiber fault point;
a third determining module 303, configured to trigger a first tapping event at a first surface tapping point, and determine a second optical fiber length between the input end and the first surface tapping point according to a first scattered light power corresponding to the first tapping event;
a fourth determining module 304, configured to determine an earth surface axial position point according to a difference between the first optical fiber length and the second optical fiber length, where the earth surface axial position point is an earth surface position point corresponding to the fault point along the optical fiber axial direction;
a fifth determining module 305, configured to determine a plurality of second surface tapping points to be tapped along the axial direction of the perpendicular optical fiber, with the surface axial position point as a center;
a sixth determining module 306, configured to trigger a second tapping event at each second surface tapping point, determine, according to second scattered light power corresponding to the second tapping event, a target surface tapping point from the plurality of second surface tapping points to be tapped, and use the target surface tapping point as a surface location point corresponding to the fault point.
In one possible implementation manner, in the process of laying the optical fiber, a plurality of optical fiber identifiers are arranged at the surface positions corresponding to the optical fiber along the axial direction of the optical fiber;
the second determining module 302 is configured to obtain a surface location point corresponding to the optical fiber fault point, determine an optical fiber identifier nearest to the surface location point corresponding to the optical fiber fault point, and take a location of the optical fiber identifier as a first surface tapping point.
In another possible implementation, the fourth determining module 304 is configured to determine the first surface tapping point as the surface axial location point when the difference between the first optical fiber length and the second optical fiber length is zero; or, the fourth determining module is used for determining a plurality of third surface knocking points to be knocked between the surface position point corresponding to the optical fiber fault point and the optical fiber identifier along the optical fiber axial direction when the difference value between the first optical fiber length and the second optical fiber length is not zero; triggering a third knocking event at each third earth surface knocking point, and determining the length of a third optical fiber between the input end and the third earth surface knocking point according to third scattered light power corresponding to the third knocking event; and selecting a surface axial position point with the length of the first optical fiber being the same as that of the third optical fiber from a plurality of third surface knocking points to be knocked.
In another possible implementation manner, the third determining module 303 includes:
the detection unit is used for detecting scattered light power in the optical fiber in the process of triggering the first knocking event to obtain a first relation curve between detection time and the scattered light power;
the first determining unit is used for determining that the scattered light power with the largest light power change is the first scattered light power corresponding to the first knocking event according to the first relation curve;
a second determining unit for determining a first detection time corresponding to the first scattered light power,
and the third determining unit is used for determining the second optical fiber length between the input end and the first surface knocking point according to the first detection time.
In another possible implementation manner, the third determining unit is configured to obtain an emission time of the pulse laser, and determine a time difference between the first detection time and the emission time; according to the time difference, determining the length of a second optical fiber between the input end and the first surface knocking point through the following formula I;
equation one: τ 2 ＝2n g l 2 /c
Wherein l 2 Representing the second fiber length τ 2 Represents the time difference between the first detection time and the emission time, c represents the speed of light, n g Indicating the refractive index of the fiber.
In another possible implementation manner, the sixth determining module 306 is configured to detect the scattered light power in the optical fiber during the triggering of the second tapping event, so as to obtain a second relationship between the detection time and the scattered light power; according to the second relation curve, determining the scattered light power with the largest light power change as second scattered light power corresponding to a second knocking event; and selecting a target surface tapping point with the maximum second scattered light power from a plurality of second surface tapping points to be tapped.
In another possible implementation, the apparatus further includes:
the adjusting module is used for adjusting the pulse width value in the pulse laser to a preset pulse width value.
In another possible implementation manner, the first determining module 301 is configured to detect the scattered light power in the optical fiber during the process of inputting the pulse laser, so as to obtain a third relationship between the detection time and the scattered light power; determining the breakpoint position of the sudden decrease of the scattered light power in the third relation curve according to the third relation curve; and determining the length of the first optical fiber between the input end and the optical fiber fault point by taking the breakpoint position as the optical fiber fault point.
The embodiment of the application provides a positioning device for fault points in optical fibers, which is characterized in that the fault points in the optical fibers are coarsely positioned to obtain first earth surface knocking points, then the first knocking events are triggered at the first earth surface knocking points, the fault points are positioned in the axial dimension of the optical fibers to obtain earth surface axial position points of the fault points, the earth surface axial position points are taken as the center, the second knocking events are triggered at a plurality of second earth surface knocking points perpendicular to the axial direction of the optical fibers, the fault points are positioned in the transverse dimension of the optical fibers, and finally the earth surface position points corresponding to the fault points are determined. Therefore, the device can position the fault point from the two dimensions of the axial dimension and the transverse dimension of the optical fiber based on the knocking event, so that the earth surface position point corresponding to the fault point is accurately positioned, and the accuracy of positioning the fault point in the optical fiber can be improved.
The foregoing description of the preferred embodiments is merely exemplary in nature and is in no way intended to limit the invention, since it is intended that all modifications, equivalents, improvements, etc. that fall within the spirit and scope of the invention.
Claims (9)
1. A method of locating a fault point in an optical fiber, the method comprising:
inputting pulse laser at an input end of an optical fiber to be tested, and determining a first optical fiber length between the input end and an optical fiber fault point according to the pulse laser, wherein the optical fiber fault point is a position point of the fault point on the optical fiber;
determining a first earth surface knocking point to be knocked according to the optical fiber fault point;
triggering a first knocking event at the first earth surface knocking point, and detecting scattered light power in the optical fiber in the process of triggering the first knocking event to obtain a first relation curve between detection time and the scattered light power;
according to the first relation curve, determining the scattered light power with the largest light power change as the first scattered light power corresponding to the first knocking event;
determining a first detection time corresponding to the first scattered light power;
determining a second optical fiber length between the input end and the first surface knocking point according to the first detection time;
Determining an earth surface axial position point according to the difference value between the first optical fiber length and the second optical fiber length, wherein the earth surface axial position point is an earth surface position point corresponding to the fault point along the optical fiber axial direction;
a plurality of second earth surface knocking points to be knocked along the axial direction of the optical fiber are determined by taking the earth surface axial position point as the center;
triggering a second knocking event at each second earth surface knocking point, determining a target earth surface knocking point from the plurality of second earth surface knocking points to be knocked according to second scattered light power corresponding to the second knocking event, and taking the target earth surface knocking point as an earth surface position point corresponding to the fault point.
2. The positioning method according to claim 1, wherein a plurality of optical fiber marks are provided along an axial direction of the optical fiber at a surface position corresponding to the optical fiber during laying of the optical fiber;
the determining a first earth surface knocking point to be knocked according to the optical fiber fault point comprises the following steps:
and acquiring the earth surface position point corresponding to the optical fiber fault point, determining an optical fiber mark nearest to the earth surface position point corresponding to the optical fiber fault point, and taking the position of the optical fiber mark as the first earth surface knocking point.
3. The positioning method according to claim 2, wherein determining the surface axial position point based on the difference between the first optical fiber length and the second optical fiber length comprises:
when the difference value between the first optical fiber length and the second optical fiber length is zero, determining the first earth surface knocking point as an earth surface axial position point; or alternatively, the process may be performed,
when the difference value between the first optical fiber length and the second optical fiber length is not zero, a plurality of third surface knocking points to be knocked between the surface position points corresponding to the optical fiber fault points and the optical fiber identifiers are determined along the axial direction of the optical fibers;
triggering a third knocking event at each third earth surface knocking point, and determining a third optical fiber length between the input end and the third earth surface knocking point according to third scattered light power corresponding to the third knocking event;
and selecting the surface axial position point with the length of the first optical fiber being the same as that of the third optical fiber from the plurality of third surface knocking points to be knocked.
4. The positioning method according to claim 1, wherein determining a second fiber length between the input end and the first surface tapping point according to the first detection time includes:
Acquiring the emission time of the pulse laser, and determining the time difference between the first detection time and the emission time;
determining a second optical fiber length between the input end and the first surface knocking point according to the time difference through the following formula I;
equation one: τ 2 ＝2n g l 2 /c
Wherein l 2 Representing the second optical fiber length τ 2 Represents the time difference between the first detection time and the emission time, c represents the speed of light, n g Representing the refractive index of the optical fiber.
5. The positioning method according to claim 1, wherein determining a target surface tapping point from the plurality of second surface tapping points to be tapped according to the second scattered light power corresponding to the second tapping event includes:
detecting scattered light power in the optical fiber in the process of triggering a second knocking event to obtain a second relation curve between detection time and the scattered light power;
determining the scattered light power with the largest light power change as second scattered light power corresponding to the second knocking event according to the second relation curve;
and selecting a target surface tapping point with the maximum second scattered light power from the plurality of second surface tapping points to be tapped.
6. The positioning method according to claim 1, wherein the triggering of the first tapping event at the first surface tapping point is performed by detecting scattered light power in the optical fiber during the triggering of the first tapping event, and before obtaining the first relation between the detection time and the scattered light power, the method further comprises:
and adjusting the pulse width value in the pulse laser to a preset pulse width value.
7. The positioning method according to claim 1, wherein said determining a first fiber length between said input end and a fiber fault point from said pulsed laser comprises:
in the process of inputting the pulse laser, detecting the scattered light power in the optical fiber to obtain a third relation curve between the detection time and the scattered light power;
determining a breakpoint position of sudden reduction of scattered light power in the third relation curve according to the third relation curve;
and taking the breakpoint position as an optical fiber fault point, and determining the first optical fiber length between the input end and the optical fiber fault point.
8. A device for locating a fault point in an optical fiber, the device comprising:
The first determining module is used for inputting pulse laser at the input end of the optical fiber to be detected, determining the first optical fiber length between the input end and an optical fiber fault point according to the pulse laser, wherein the optical fiber fault point is a position point of the fault point on the optical fiber;
the second determining module is used for determining a first earth surface knocking point to be knocked according to the optical fiber fault point;
the third determining module is used for triggering a first knocking event at the first earth surface knocking point, and detecting scattered light power in the optical fiber in the process of triggering the first knocking event to obtain a first relation curve between detection time and the scattered light power; according to the first relation curve, determining the scattered light power with the largest light power change as the first scattered light power corresponding to the first knocking event; determining a first detection time corresponding to the first scattered light power; determining a second optical fiber length between the input end and the first surface knocking point according to the first detection time;
a fourth determining module, configured to determine a surface axial position point according to a difference between the first optical fiber length and the second optical fiber length, where the surface axial position point is a surface position point corresponding to the fault point along the optical fiber axial direction;
A fifth determining module, configured to determine a plurality of second surface tapping points to be tapped along a direction perpendicular to the axial direction of the optical fiber, with the surface axial position point as a center;
and a sixth determining module, configured to trigger a second tapping event at each second surface tapping point, determine a target surface tapping point from the plurality of second surface tapping points to be tapped according to second scattered light power corresponding to the second tapping event, and use the target surface tapping point as a surface location point corresponding to the fault point.
9. The positioning device according to claim 8, wherein a plurality of optical fiber marks are provided along an axial direction of the optical fiber at a surface position corresponding to the optical fiber during laying of the optical fiber;
the second determining module is configured to obtain a surface location point corresponding to the optical fiber fault point, determine an optical fiber identifier nearest to the surface location point corresponding to the optical fiber fault point, and take a location of the optical fiber identifier as the first surface knocking point.
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