A method for locating the spatial position of a cable fault

Abstract

The present application relates to the technical field of optical cable fault location, and discloses a method for locating the spatial position of a cable fault, comprising: obtaining 3D network data of the optical cable, constructing a topological map describing the connection status of the optical cable; performing OTDR detection on the optical cable, and calculating the fault distance between the fault point and the detection point based on the optical time domain reflection signal; exploring the fault path between the fault point and the detection point in the topological map; if there is only one fault path, spatially locating the fault point; if there are at least two fault paths, extracting the attenuation characteristics of the optical time domain reflection signal; screening the fault path based on the attenuation characteristics, and spatially locating the fault point; the present application can achieve accurate mapping of the cable fault point to the 3D spatial model, providing strong support for quickly locating and repairing cable faults.

Description

Technical Field

[0001] The present application relates to the technical field of optical cable fault location, and in particular to a method for locating the spatial position of a cable fault. Background Art

[0002] In traditional cable fault detection scenarios, while an optical time-domain reflectometer (OTDR) can accurately measure the distance between the fault point and the measurement end on the cable, it cannot determine the specific location of the fault point in real space. Due to the complexities of cable laying, such as tangles, bends, and pre-existing cables, once a fault occurs, relying solely on the distance information provided by the OTDR is difficult to quickly and accurately locate. This often requires a significant amount of manpower for on-site investigation, a tedious and time-consuming process that impacts cable repair efficiency.

[0003] An optical time domain reflectometer locates the fault point by detecting the time and intensity of the reflected and backscattered signals of light pulses in the optical fiber. When an optical cable has branches, a traditional optical time domain reflectometer detects the superimposed backscattered signals of multiple branches. If a branch has a fault such as a breakpoint, a single optical time domain reflectometer cannot distinguish which branch the fault is located on. It is necessary to combine other detection methods, such as an optical power meter, a visual fault locator, or add detection points at the branch to perform multiple rounds of OTDR testing. The equipment configuration cost is high, and the need for multiple rounds of testing leads to low detection efficiency, which increases the workload of daily network operation and maintenance. In addition, when multiple branches have faults, due to the superposition of waveforms, traditional OTDR methods cannot distinguish the fault location, resulting in misjudgment of the fault point.

[0004] For example, a Chinese patent with authorization announcement number CN104009793B discloses a method for locating optical cable faults, including: 1) traversing optical cables, finding all optical cables carrying faulty services and placing them in a faulty optical cable set; 2) finding the minimum number of optical cables carrying all faulty services and placing them in a suspected optical cable set; a. setting the number of faulty optical cables i = 1; b. finding i optical cables in the faulty optical cable set, and determining whether all optical cables contained in the suspected optical cable set are within these i optical cables; if not, determining whether these i optical cables can carry all faulty services, and if so, placing these i optical cables in the suspected optical cable set; c. setting the number of faulty optical cables plus 1, and repeating step b above; 3) sorting the members of the suspected optical cable set, so that members carrying fewer services are more likely to have faults. This technical solution can help staff quickly locate the range of optical cables that may be faulty, provide an accurate basis for the next on-site line inspection, and improve the efficiency of locating faulty optical cables.

[0005] For example, Chinese patent application CN114157348B discloses a method for locating an optical cable fault point. This method draws a target geographic range containing the fault point on a map based on the geographic coordinates of a first reference point, the geographic coordinates of a second reference point, the cable length between the first reference point and the access terminal of a target optical cable, the cable length between the second reference point and the access terminal of the target optical cable, and the cable length between the fault point and the access terminal of the target optical cable. By narrowing the search range of the fault point to the target geographic range, the difficulty and time of searching for the fault point are reduced, facilitating rapid repair of the optical cable.

[0006] The above patents all have the problems raised by this background technology: low detection efficiency, and when faults occur in multiple branches, it is impossible to distinguish the fault locations.

[0007] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the application and should not be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to ordinary technicians in this field. Summary of the Invention

[0008] The technical problem to be solved by this application is to overcome the defects of the existing technology and provide a method for locating the spatial position of cable faults, accurately mapping the cable fault points to a 3D spatial model, and providing support for rapid positioning and repair of cable faults.

[0009] To solve the above technical problems, this application provides the following technical solutions:

[0010] A method for locating a cable fault spatial position comprises the following steps:

[0011] Obtain 3D network data of optical cables and construct a topology diagram describing the optical cable connections;

[0012] Performing OTDR detection on the optical cable to collect optical time domain reflection signals; calculating the fault distance between the fault point and the detection point based on the optical time domain reflection signals;

[0013] Based on the fault distance, exploring a fault path between a fault point and a detection point in the topology map;

[0014] If there is only one fault path, the fault point is spatially located, specifically including: spatially locating the fault point based on the attribute information corresponding to the fault path in the topology graph;

[0015] If there are at least two fault paths, the attenuation characteristics of the optical time domain reflectometry signal are extracted; the fault path is screened based on the attenuation characteristics, and the fault point is spatially located.

[0016] As a preferred solution of the method for locating the spatial position of a cable fault described in the present application, the 3D network data of the optical cable includes the number, length, direction, attenuation coefficient of the optical cable, and the model, number, spatial coordinates, and attenuation coefficient of the optical splitter; and also includes the position of a known loss point in the optical cable and the attenuation coefficient of the loss point;

[0017] The method of constructing a topological graph describing the optical cable connection specifically includes: marking any optical splitter as a node; connecting the nodes with edges based on the actual connection status of the optical cable; adding attribute information for each node, including the model, number, and spatial coordinates of the optical splitter; and adding attribute information for each edge, including the number, winding distance, routing direction, and attenuation coefficient of the optical cable segment corresponding to the edge, as well as the position of each known loss point in the optical cable contained in the optical cable segment corresponding to the edge and the attenuation coefficient of the loss point.

[0018] As a preferred solution of the method for locating the spatial position of a cable fault described in the present application, wherein: the optical time domain reflection signal includes a reflection signal and a backscattered signal of a light pulse generated by an optical time domain reflectometer reflected in an optical cable; the fault point is the location where the fault occurs in the optical cable; the detection point is the location of the optical cable connected to the optical time domain reflectometer; the optical time domain reflectometer injects a light pulse into the optical cable at the test point;

[0019] The fault distance is the length of the optical cable between the fault point and the detection point; and calculating the fault distance between the fault point and the detection point based on the optical time domain reflectometer signal specifically includes:

[0020] Identifying a fault waveform in the optical time domain reflectometer signal; recording a time delay value of the fault waveform; wherein the fault waveform is a segment of the optical time domain reflectometer signal reflected from the fault point; and the time delay value is the time difference between the moment when the optical time domain reflectometer injects an optical pulse into the optical cable and the moment when the fault waveform is received;

[0021] The fault distance is calculated based on the time delay value and the propagation speed of the optical pulse in the optical cable.

[0022] As a preferred solution of the method for locating the spatial position of a cable fault described in the present application, wherein: the fault path is a topological path between a potential fault point and the detection point in a topological map; the potential fault point is a point in the topological map where the length of the optical cable segment between the potential fault point and the detection point is equal to the fault distance;

[0023] Exploring the fault path between the fault point and the detection point in the topology diagram specifically includes:

[0024] Locating the detection point in the topology map; the detection point is an optical splitter, corresponding to a node in the topology map;

[0025] In the topology diagram, starting from the detection point, exploration is carried out along the direction of the light pulse injected by the optical time domain reflectometer, and the exploration path is updated in real time. The length of the exploration path is calculated based on the winding distance of the optical cable segment corresponding to the edge involved in the exploration path. When the length of the exploration path reaches the fault distance, the exploration is stopped and the location where the exploration is stopped is marked as a potential fault point. The exploration path between any potential fault point and the detection point is the fault path corresponding to the potential fault point.

[0026] As a preferred solution of the method for locating the spatial position of a cable fault in the present application, wherein: exploring the fault path between the fault point and the detection point in the topology map further includes:

[0027] If the node corresponding to the spectrometer is passed during the exploration along the direction of the light pulse injected by the optical time domain reflectometer, the current length of the exploration path is recorded when passing the node corresponding to the spectrometer; the current length is the sum of the lengths corresponding to all edges contained in the exploration path between the detection point and the node corresponding to the spectrometer; the difference between the fault distance and the current length is calculated as the remaining fault distance; starting from the node corresponding to the spectrometer, the exploration is restarted along each edge connected to the node corresponding to the spectrometer, and the exploration path is updated in real time; when the length of the exploration path reaches the remaining fault distance, the exploration is stopped, and the location where the exploration is stopped is marked as a potential fault point.

[0028] As a preferred solution of the method for locating the spatial position of a cable fault described in the present application, the attribute information corresponding to the fault path in the topological graph includes the number, winding distance, and routing direction of the optical cable segment corresponding to each edge involved in the fault path, and the number and spatial coordinates of the optical splitter corresponding to each node involved in the fault path;

[0029] The spatial positioning of the fault point based on the attribute information of the corresponding fault path in the topology map specifically includes:

[0030] Based on the edge of the potential fault point corresponding to the fault path in the topology graph, determine the number of the optical cable segment where the fault point is located;

[0031] Mark the node closest to the potential fault point in the fault path as the upstream node of the potential fault point; calculate the length of the optical cable between the upstream node and the fault point; the difference between the fault distance and the sum of the coiled distances of the optical cable segments between the detection point and the upstream node is the length of the optical cable between the upstream node and the fault point;

[0032] Record the location information of the spatial position of the fault point; the location information includes the number of the optical cable segment, the routing direction, the number and spatial coordinates of the upstream node, and the length of the optical cable between the upstream node and the fault point.

[0033] As a preferred solution of the method for locating the spatial position of a cable fault described in the present application, wherein: the attenuation characteristic includes the continuous attenuation rate of the optical time domain reflectance signal in the fault path; screening the fault path based on the attenuation characteristic specifically includes:

[0034] S100: Construct the theoretical decay sequence of each fault path;

[0035] S200: Select a fault path as a target fault path;

[0036] S300: Calculate the interference reflection envelope of the target fault path based on the theoretical attenuation sequence of each fault path; specifically include: marking all fault paths other than the target fault path as non-target paths; calculating the independent reflection envelope of each non-target path; and summing the amplitudes of the independent reflection envelopes of all non-target paths to obtain the interference reflection envelope of the target fault path.

[0037] S400: Calculating a target reflection envelope of a target fault path based on the interference reflection envelope; specifically comprising: correcting a time delay difference between the optical time domain reflection signal and the interference reflection envelope using a cross-correlation algorithm; performing waveform subtraction between the optical time domain reflection signal and the interference reflection envelope to obtain the target reflection envelope;

[0038] S500: Calculating the credibility of a target fault path based on the target reflection envelope;

[0039] S600: Repeat S200 to S500 until the credibility of all fault paths is obtained;

[0040] S700: Only the fault path with the highest credibility is retained, and all other fault paths are eliminated.

[0041] As a preferred solution of the method for locating the spatial position of a cable fault described in the present application, the elements in the theoretical attenuation sequence are the attenuation coefficients of the optical cable at different positions in the fault path; the method for constructing the theoretical attenuation sequence of any fault path is as follows:

[0042] Mark an attenuation exploration segment in the fault path; the starting point of the attenuation exploration segment is the detection point, the length of the optical cable between the end point and the starting point is D, and the potential fault point corresponding to the fault path is located between the detection point and the end point;

[0043] Based on the attribute information of the edge, the position of the known loss point in the optical cable and the attenuation coefficient of the loss point in the attenuation exploration segment are obtained; each loss point is marked as a sampling point, and the attenuation coefficient of each sampling point is recorded;

[0044] Supplementing sampling points in the attenuation exploration segment so that the supplemented sampling points are evenly distributed in the attenuation exploration segment; determining the attenuation coefficient of each supplemented sampling point based on the attribute information of the edge where each supplemented sampling point is located;

[0045] The attenuation coefficients of all sampling points are sorted into the theoretical attenuation sequence of the fault path in the order from near to far from the potential fault point.

[0046] As a preferred solution of the method for locating the spatial position of a cable fault described in the present application, the method for calculating the independent reflection envelope of any non-target path is as follows:

[0047] The theoretical attenuation sequence of the non-target path is converted into a continuous attenuation sequence function through linear interpolation;

[0048] Convolving the attenuation sequence function with a time domain signal of an optical pulse injected into the optical cable by an optical time domain reflectometer to obtain an independent reflection envelope of a non-target path;

[0049] The independent reflection envelope is subjected to amplitude correction based on the light splitting ratio of the non-target path.

[0050] As a preferred solution of the method for locating the spatial position of a cable fault described in the present application, the reliability of the target fault path is calculated based on the target reflection envelope, specifically including:

[0051] intercepting a segment after the fault waveform in the optical time domain reflectometer signal as a reference waveform segment;

[0052] detecting waveform steps in the reference waveform segment and marking a timestamp for each waveform step;

[0053] Based on the timestamp, it is detected whether each waveform step disappears in the target reflection envelope; and the number of waveform steps that disappear in the target reflection envelope is recorded as the credibility of the target fault path.

[0054] As a preferred solution of the method for locating the spatial position of a cable fault described in the present application, the 3D network data is obtained based on a 3D model of the optical cable; and the method for constructing the 3D model is as follows:

[0055] Based on GIS geographic information data, use 3D modeling software to build a 3D basic framework of topography;

[0056] Extract the optical cable location data from the GIS system, including the longitude and latitude coordinates, burial depth and elevation data of the optical cable path;

[0057] Integrate the fiber optic cable node data collected on-site, including the location of the pipe well, the coordinates of the coiled area, the spatial coordinates of the splice box, and the length of the fiber optic cable; and construct a 3D model of the fiber optic cable, including:

[0058] Based on the optical cable position data and the optical cable node data, the actual direction of the optical cable is fitted by a B-spline curve to achieve the marking of the spatial coordinates of the optical cable;

[0059] The difference between the actual cable length and the straight-line distance in space is calculated using a spiral equation, and the number of coils and the coil diameter of the coil area are set based on the difference to achieve coil area modeling.

[0060] 3D network data is organized and labeled for each section of optical cable in the 3D model; and the 3D model is integrated into a three-dimensional basic framework of the topography based on the spatial coordinates of the optical cables.

[0061] As a preferred solution of the method for locating the spatial position of a cable fault described in the present application, the method further includes: spatially locating the fault point based on the fault distance and the 3D model, specifically including:

[0062] Convert the 3D model of the optical cable into a weighted directed graph, where nodes represent cable connection points, edges represent cable segments, and the edge weight is the cable length;

[0063] A heuristic search algorithm is used to find potential fault paths that match the fault distance in a weighted directed graph, and the potential fault points corresponding to each potential fault path are marked.

[0064] Calculate the credibility of each potential fault path based on the fault prediction model, and retain the potential fault path with the highest credibility and the corresponding fault point;

[0065] Based on spatial coordinates, the fault location and the optical cable direction of the potential fault path are visually marked in the 3D model.

[0066] Compared with the prior art, the beneficial effects achieved by this application are as follows:

[0067] This application uses OTDR, 3D modeling, geographic information system (GIS) and artificial intelligence technology to accurately map cable fault points to a 3D spatial model, providing strong support for quickly locating and repairing cable faults.

[0068] This application enhances the interpretability of AI algorithms through the topological prior knowledge of 3D models, solving the problem of failure of traditional OTDR to locate faults in branching scenarios; in multi-branch or more complex optical cable network topologies, it improves the accuracy of fault branch identification; even if the branches are similar in length or there are fault points on multiple branches at the same time, the branch to which the breakpoint belongs can still be accurately located. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be derived from these drawings without inventive effort. Among them:

[0070] Figure 1 A flowchart of a method for locating the spatial position of a cable fault provided in this application;

[0071] Figure 2 A flow chart of the method for screening fault paths provided in this application;

[0072] Figure 3 A schematic diagram of a fault path with potential fault points marked is provided for this application. DETAILED DESCRIPTION

[0073] The technical solution of the present application is described in detail below through the accompanying drawings and specific embodiments. It should be understood that the embodiments of the present application and the specific features in the embodiments are detailed descriptions of the technical solution of the present application, rather than limitations on the technical solution of the present application. Unless there is a conflict, the embodiments of the present application and the technical features in the embodiments can be combined with each other.

[0074] This embodiment introduces a method for locating the spatial position of a cable fault. Figure 1 , the method comprises the following steps:

[0075] Obtain 3D network data of optical cables and construct a topology diagram describing the optical cable connections;

[0076] The 3D network data of the optical cable includes the number, length, direction, attenuation coefficient of the optical cable, as well as the model, number, spatial coordinates, and attenuation coefficient of the splitter; it also includes the position of the known loss point in the optical cable and the attenuation coefficient of the loss point; the known loss point is the position in the optical cable where there is fixed loss attenuation and the attenuation coefficient is known, such as optical fiber joints, splicing boxes, bends, etc.

[0077] The construction of a topological graph describing the optical cable connection specifically includes: marking any optical splitter as a node; connecting the nodes with edges based on the actual connection status of the optical cable; adding attribute information to each node, including the model, number, and spatial coordinates of the optical splitter; adding attribute information to each edge, including the number, winding distance, routing direction, and attenuation coefficient of the optical cable segment corresponding to the edge, as well as the location of each known loss point in the optical cable contained in the optical cable segment corresponding to the edge and the attenuation coefficient of the loss point;

[0078] The length, orientation, and attenuation coefficient of the optical cable in the 3D network data are used to determine the winding distance, routing direction, and attenuation coefficient of each optical cable segment corresponding to each edge. The attenuation coefficient represents the optical fiber's loss characteristics, specifically the ratio of optical power attenuation within the cable. Each type of optical cable and splitter has an initial attenuation coefficient. As optical fiber loss increases over time, the attenuation coefficient also increases. When the attenuation coefficient of optical cables and splitters, along with other 3D network data, is updated during actual maintenance, testing, and maintenance, the attribute information in the topology map is updated simultaneously.

[0079] Performing OTDR detection on the optical cable to collect optical time domain reflection signals; calculating the fault distance between the fault point and the detection point based on the optical time domain reflection signals;

[0080] The optical time domain reflection signal includes the reflection signal and backscattering signal of the light pulse generated by the optical time domain reflectometer reflected in the optical cable; for example, the continuous backscattering signal generated by optical fiber Rayleigh scattering, and the reflection signal caused by faults such as optical cable breakage.

[0081] The fault point is the location where a fault occurs in the optical cable, for example, the location of a fault such as a broken optical cable or deteriorated splice box.

[0082] The detection point is the position of the optical cable connected to the optical time domain reflectometer; the optical time domain reflectometer injects a light pulse into the optical cable at the test point; the spatial coordinates of the test point are known quantities and can be directly marked in the topology map.

[0083] The fault distance is the length of the optical cable between the fault point and the detection point; and calculating the fault distance between the fault point and the detection point based on the optical time domain reflectometer signal specifically includes:

[0084] Identify a fault waveform in the optical time domain reflectometer signal; record the time delay of the fault waveform; wherein the fault waveform is a segment of the optical time domain reflectometer signal reflected from the fault point; and the time delay is the time difference between the moment the optical time domain reflectometer injects an optical pulse into the optical cable and the moment the fault waveform is received. The optical time domain reflectometer can automatically identify a fault waveform, for example, an optical time domain reflectometer signal segment with an amplitude exceeding the adjacent Rayleigh scattering floor by more than 10 dB and a pulse width between 5 ns and 50 ns is a fault waveform.

[0085] The fault distance is calculated based on the time delay and the optical pulse's propagation speed in the optical cable. The optical pulse's propagation speed is relatively stable for each type of optical cable, maintaining a fixed ratio to the speed of light and related to the effective refractive index of the cable material. The optical distance traveled by the optical pulse from the detection point to the fault point and back again is twice the fault distance.

[0086] Based on the fault distance, exploring a fault path between a fault point and a detection point in the topology map;

[0087] The fault path is a topological path between a potential fault point and the detection point in the topological map; the potential fault point is a point in the topological map where the length of the optical cable segment between the potential fault point and the detection point is equal to the fault distance;

[0088] Exploring the fault path between the fault point and the detection point in the topology diagram specifically includes:

[0089] Locating the detection point in the topology map; the detection point is an optical splitter, corresponding to a node in the topology map;

[0090] In the topology diagram, starting from the detection point, exploration is performed along the direction of the optical pulse injected by the optical time domain reflectometer, and the exploration path is updated in real time. The length of the exploration path is calculated based on the winding distance of the optical cable segment corresponding to the edge involved in the exploration path. When the length of the exploration path reaches the fault distance, the exploration is stopped and the location where the exploration is stopped is marked as a potential fault point. The exploration path between any potential fault point and the detection point is the fault path corresponding to the potential fault point.

[0091] If the node corresponding to the spectrometer is passed during the exploration along the direction of the light pulse injected by the optical time domain reflectometer, the current length of the exploration path is recorded when passing the node corresponding to the spectrometer; the current length is the sum of the lengths corresponding to all edges contained in the exploration path between the detection point and the node corresponding to the spectrometer; the difference between the fault distance and the current length is calculated as the remaining fault distance; starting from the node corresponding to the spectrometer, the exploration is restarted along each edge connected to the node corresponding to the spectrometer, and the exploration path is updated in real time; when the length of the exploration path reaches the remaining fault distance, the exploration is stopped, and the location where the exploration is stopped is marked as a potential fault point.

[0092] By exploring the fault path, we can screen all possible propagation paths of the fault waveform that meet the cable length constraint, that is, all possible locations of the fault point. For example, if the fault distance is 1100 meters, starting from the detection point, it passes through a 1-kilometer trunk cable to the splitter. The splitter is connected to branch cable A with a 50-meter reel length, branch cable B with a 150-meter reel length, and branch cable C with a 200-meter reel length. The potential fault point can be discovered on branch cables B and C, indicating that the fault point is actually located on branch cable B or C.

[0093] If there is only one fault path, the fault point is spatially located, specifically including: spatially locating the fault point based on the attribute information corresponding to the fault path in the topology graph;

[0094] The attribute information corresponding to the fault path in the topology graph includes the number, winding distance, and routing direction of the optical cable segment corresponding to each edge involved in the fault path, and the number and spatial coordinates of the optical splitter corresponding to each node involved in the fault path;

[0095] The spatial positioning of the fault point based on the attribute information of the corresponding fault path in the topology map specifically includes:

[0096] Based on the edge of the potential fault point corresponding to the fault path in the topology graph, determine the number of the optical cable segment where the fault point is located;

[0097] Mark the node closest to the potential fault point in the fault path as the upstream node of the potential fault point; calculate the length of the optical cable between the upstream node and the fault point; the difference between the fault distance and the sum of the coiled distances of the optical cable segments between the detection point and the upstream node is the length of the optical cable between the upstream node and the fault point;

[0098] Record the location information of the spatial position of the fault point; the location information includes the number of the optical cable segment, the routing direction, the number and spatial coordinates of the upstream node, and the length of the optical cable between the upstream node and the fault point.

[0099] Based on the above description information, this application maps the fault distance detected by the OTDR into positioning information in real space, providing strong support for quickly locating and repairing cable faults.

[0100] If there are at least two fault paths, the attenuation characteristics of the optical time domain reflectometry signal are extracted; the fault path is screened based on the attenuation characteristics, and the fault point is spatially located.

[0101] The attenuation characteristics include the continuous attenuation rate of the optical time domain reflection signal in the fault path; Figure 2 , screening the fault path based on the attenuation characteristics, specifically including:

[0102] S100: Construct the theoretical decay sequence of each fault path;

[0103] The elements in the theoretical attenuation sequence are the attenuation coefficients at different locations of the optical cable in the fault path. The method for constructing the theoretical attenuation sequence for any fault path is as follows:

[0104] Mark an attenuation exploration segment in the fault path; the starting point of the attenuation exploration segment is the detection point, the length of the optical cable between the end point and the starting point is D, and the potential fault point corresponding to the fault path is located between the detection point and the end point; the value of D is set by those skilled in the art based on actual needs, for example, D is 1.5 times the fault distance;

[0105] Based on the attribute information of the edge, the position of the known loss point in the optical cable and the attenuation coefficient of the loss point in the attenuation exploration segment are obtained; each loss point is marked as a sampling point, and the attenuation coefficient of each sampling point is recorded;

[0106] Supplementing sampling points in the attenuation exploration segment so that the supplemented sampling points are evenly distributed in the attenuation exploration segment; determining the attenuation coefficient of each supplemented sampling point based on the attribute information of the edge where each supplemented sampling point is located;

[0107] The attenuation coefficients of all sampling points are sorted into the theoretical attenuation sequence of the fault path in the order from near to far from the potential fault point.

[0108] S200: Select a fault path as a target fault path;

[0109] S300: Calculating the interference reflection envelope of the target fault path based on the theoretical attenuation sequence of each fault path; specifically including:

[0110] Mark all fault paths other than the target fault path as non-target paths; calculate the independent reflection envelope of each non-target path;

[0111] The independent reflection envelope of any non-target path is calculated as follows:

[0112] The theoretical attenuation sequence of the non-target path is converted into a continuous attenuation sequence function through linear interpolation;

[0113] Convolving the attenuation sequence function with a time domain signal of an optical pulse injected into the optical cable by an optical time domain reflectometer to obtain an independent reflection envelope of a non-target path;

[0114] The amplitude of the independent reflection envelope is corrected based on the splitting ratio of the non-target path. For example, if the splitter allocates 30% of the optical pulses to the branch path corresponding to the non-target path, the amplitude of the independent reflection envelope of the non-target path is multiplied by 30%. This convolution simulates the actual attenuation of the OTDR optical pulse in the optical cable of the non-target path. After amplitude correction, the independent reflection envelope represents the ideal time domain waveform of the backscattered light from the non-target path.

[0115] The independent reflection envelopes of all non-target paths are amplitude-superimposed to obtain the interference reflection envelope of the target fault path. After the independent reflection envelopes of all non-target paths are amplitude-superimposed, the time domain waveform of the backscattered light superposition of all paths except the target fault path is obtained.

[0116] S400: Calculate the target reflection envelope of the target fault path based on the interference reflection envelope; specifically including: correcting the time delay difference between the optical time domain reflection signal and the interference reflection envelope through the cross-correlation algorithm; performing waveform subtraction on the optical time domain reflection signal and the interference reflection envelope to obtain the target reflection envelope. The cross-correlation algorithm can calculate the time delay difference between the optical time domain reflection signal and the interference reflection envelope, and compensate for the time delay difference by time axis translation, so that the time steps of the optical time domain reflection signal and the interference reflection envelope are strictly aligned. Subtract the waveforms of the optical time domain reflection signal and the interference reflection envelope point by point to obtain the target reflection envelope of the target fault path. The target reflection envelope eliminates the interference of all backscattered light of non-target paths and retains the time domain signal waveform of the backscattered light in the target fault path.

[0117] S500: Calculating the credibility of the target fault path based on the target reflection envelope; specifically including:

[0118] intercepting a segment after the fault waveform in the optical time domain reflectometer signal as a reference waveform segment;

[0119] detecting waveform steps in the reference waveform segment and marking a timestamp for each waveform step;

[0120] Based on the timestamp, it is detected whether each waveform step disappears in the target reflection envelope; and the number of waveform steps that disappear in the target reflection envelope is recorded as the credibility of the target fault path.

[0121] In this embodiment, the credibility of the target fault path is determined by the number of waveform step disappearances. A waveform step is a sudden change in slope caused by a known loss point in the optical time domain reflectance signal and the target reflection envelope of any fault path. Slope changes at reflection peaks are not counted as step waveforms. The attenuation coefficient at a known loss point differs significantly from that of the normal optical cable segments before and after the loss point, manifesting as a sudden change in slope in the optical time domain reflectance signal, forming a step-like waveform. In this embodiment, the interference reflection envelope is simulated by the theoretical attenuation sequence of each non-target path. The interference reflection envelope includes step waveforms caused by known loss points in the non-target path, but does not include reflection peaks caused by strong reflection points (such as fiber end faces and connectors) in the non-target path. Therefore, in this embodiment, sudden changes in slope at reflection peaks are not counted as step waveforms.

[0122] Figure 3 A schematic diagram of the fault path with potential fault points marked is provided. The schematic diagram can be viewed as a planar projection of the 3D model of the optical cable. Figure 3The triangle marks on fault paths 1 and 2 represent known loss points. Let fault path 1 be the actual fault path, and the potential fault point on it be the actual breakpoint. Because the optical cable is disconnected at the fault point, the waveform steps caused by the two known loss points on this path are absent after the fault waveform of the optical time domain reflectometer signal. The target reflection waveform for this path has already subtracted the four waveform steps caused by fault path 2, resulting in a higher number of missing waveform steps. When fault path 2 is used as the target fault path, the waveform steps caused by the four known loss points after the potential fault point are not subtracted from the target reflection waveform, resulting in a lower number of missing waveform steps.

[0123] S600: Repeat S200 to S500 until the credibility of all fault paths is obtained;

[0124] S700: Only the fault path with the highest credibility is retained, and all other fault paths are eliminated.

[0125] This embodiment of the application compares the attenuation characteristics of each potential fault path, quantifying the confidence that the fault actually occurred on each path, thereby resolving the ambiguity problem of multiple branches at the same distance. By deeply integrating physical topology constraints with signal processing algorithms and continuously and dynamically evaluating attenuation characteristics, this method achieves more accurate fault location than traditional reflection event analysis, making it particularly suitable for fault location and diagnosis in complex branch networks.

[0126] Preferably, the 3D network data described in this embodiment is obtained based on a 3D model of an optical cable; the method for constructing the 3D model is as follows:

[0127] Based on GIS geographic information data, use 3D modeling software to build a 3D basic framework of topography;

[0128] Extract the optical cable location data from the GIS system, including the longitude and latitude coordinates, burial depth and elevation data of the optical cable path;

[0129] Integrate the fiber optic cable node data collected on-site, including the location of the pipe well, the coordinates of the coiled area, the spatial coordinates of the splice box, and the length of the fiber optic cable; and construct a 3D model of the fiber optic cable, including:

[0130] Based on the optical cable position data and the optical cable node data, the actual direction of the optical cable is fitted by a B-spline curve to achieve the marking of the spatial coordinates of the optical cable;

[0131] The difference between the actual cable length and the straight-line distance in space is calculated using a spiral equation, and the number of coils and the coil diameter of the coil area are set based on the difference to achieve coil modeling.

[0132] 3D network data is organized and labeled for each section of optical cable in the 3D model; and the 3D model is integrated into a three-dimensional basic framework of the topography based on the spatial coordinates of the optical cables.

[0133] The core contradiction of 3D modeling lies in decoupling the physical length of optical cables from their linear distances in space. Traditional GIS systems only record the location of pipeline corridors, while the actual length of optical cables can exceed the pipeline length due to reservations and coiling. This embodiment resolves this contradiction through spiral modeling and 3D network data annotation.

[0134] Furthermore, this embodiment also preferably adopts a method for spatially locating the fault point based on the fault distance measured by the OTDR and the 3D model, which specifically includes:

[0135] Convert the 3D model of the optical cable into a weighted directed graph, where nodes represent optical cable connection points such as splice boxes and splitters, edges represent optical cable segments, and the edge weight is the cable length.

[0136] A heuristic search algorithm is used to find potential fault paths that match the fault distance in a weighted directed graph and mark the potential fault points corresponding to each potential fault path. Since the edge weight is the actual cable length based on the 3D model annotation, the search process takes into account the actual cable installation configuration, including straight sections, curved sections, and coiled areas.

[0137] Calculate the credibility of each potential fault path based on the fault prediction model, and retain the potential fault path with the highest credibility and the corresponding fault point;

[0138] The fault prediction model is constructed and trained based on any one or more of an LSTM model, a GNN model, and a Transformer model. The input of the fault prediction model includes historical fault data for each edge in a weighted directed graph, as well as the attenuation coefficient of the optical cable segment corresponding to each edge, the location and attenuation coefficient of a known loss point, and optical time domain reflectometry feature data, such as reflection peak type and attenuation slope. The output of the fault prediction model is the credibility of each potential fault path actually having a fault.

[0139] Based on spatial coordinates, the fault location and the optical cable route of the potential fault path are visually annotated in the 3D model. Visual annotations in the 3D model, such as highlighting and flashing, provide the spatial coordinates of the fault point, the optical cable route between the optical time domain detection point and the fault point, and geographical features such as buildings and terrain along the route, making it easier for operation and maintenance personnel to find the actual location of the fault point.

[0140] To address the need for fault location based on optical time-domain detection and 3D models, this embodiment prefers a hybrid model that integrates GNN (graph neural network) and Transformer as a fault prediction model. This fault prediction model effectively processes weighted directed graph structure data and optical time-domain reflectometry feature data, accurately predicting the credibility of the fault path. The fault prediction model includes a data preprocessing layer, a graph embedding layer, a time series feature extraction layer, a feature fusion layer, an attention mechanism layer, and a prediction output layer. Specifically:

[0141] The data preprocessing layer is used to convert the original input data into a feature vector of uniform dimension. This layer encodes the edge features and optical time domain reflectance feature data through linear transformation.

[0142] The graph embedding layer is used to capture the topological structure and connectivity of a weighted directed graph. This layer processes the connectivity between nodes and edges through a multi-layer GCN (graph convolutional network) to extract graph structural information.

[0143] The temporal feature extraction layer is used to process the temporal features in the optical time domain reflectometry feature data, such as reflection peak type and attenuation slope. This layer uses the Transformer encoder to capture long-term dependencies in the temporal features.

[0144] The feature fusion layer is used to integrate the graph structure, edge-corresponding features, and the temporal features of the optical time-domain reflectance feature data. This layer fuses multiple features into a unified representation through linear transformation.

[0145] The attention mechanism layer is used to automatically learn the importance weights of different features. This layer uses the attention mechanism to calculate feature weights and enhance the impact of key information.

[0146] The prediction output layer is used to output the credibility of each potential fault path; this layer outputs a credibility score between 0 and 1 through a multi-layer perceptron and a Sigmoid activation function.

[0147] Furthermore, this embodiment dynamically updates the attenuation coefficients of optical cables and known loss points in the 3D network data through an online learning algorithm, as follows:

[0148] By inputting the attenuation slope from real-time optical time-domain reflectometry data and loss anomalies from historical fault records into a time-series regression model, such as an LSTM network, the model automatically learns how the optical cable attenuation coefficient changes with age, ambient temperature, and humidity, among other factors. When the deviation between the actual attenuation value detected in real time and the theoretical attenuation coefficient recorded in the topology map exceeds a threshold, such as 5%, a parameter update is triggered, dynamically adjusting the attenuation coefficient for the corresponding optical cable segment or known loss point and synchronizing it with the topology map attribute information in the 3D network model and GIS system. This process, requiring no human intervention, tracks loss changes caused by optical cable aging in real time, ensuring the accuracy and timeliness of the attenuation coefficient in the topology map, and providing more reliable basic data for fault path exploration and credibility calculations.

[0149] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present application may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0150] The above describes the embodiments of the present application in conjunction with the accompanying drawings, but the present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of this application, ordinary technicians in this field can also make many forms without departing from the purpose and scope of protection of this application, all of which are protected by this application.

Claims

1. A method for locating the spatial position of a cable fault, characterized in that: The following steps are involved: Obtain 3D network data of optical cables and construct a topology diagram describing the optical cable connections; Performing OTDR detection on the optical cable to collect optical time domain reflection signals; calculating the fault distance between the fault point and the detection point based on the optical time domain reflection signals; Based on the fault distance, exploring a fault path between a fault point and a detection point in the topology map; If there is only one fault path, the fault point is spatially located, specifically including: spatially locating the fault point based on the attribute information corresponding to the fault path in the topology graph; If there are at least two fault paths, extract the attenuation characteristics of the optical time domain reflectometer signal; screen the fault path based on the attenuation characteristics, and spatially locate the fault point; The attenuation characteristic includes a continuous attenuation rate of an optical time domain reflectometer signal in the fault path. Screening the fault path based on the attenuation characteristic specifically includes: S100: Construct the theoretical decay sequence of each fault path; S200: Select a fault path as a target fault path; S300: Calculating the interference reflection envelope of the target fault path based on the theoretical attenuation sequence of each fault path; specifically, marking all fault paths other than the target fault path as non-target paths; calculating the independent reflection envelope of each non-target path; and summing the amplitudes of the independent reflection envelopes of all non-target paths to obtain the interference reflection envelope of the target fault path; S400: Calculating a target reflection envelope of a target fault path based on the interference reflection envelope; specifically comprising: correcting a time delay difference between the optical time domain reflection signal and the interference reflection envelope using a cross-correlation algorithm; performing waveform subtraction between the optical time domain reflection signal and the interference reflection envelope to obtain the target reflection envelope; S500: Calculating the credibility of a target fault path based on the target reflection envelope; S600: Repeat S200 to S500 until the credibility of all fault paths is obtained; S700: Only the fault path with the highest credibility is retained, and all other fault paths are eliminated.

2. The method for locating a cable fault spatial position according to claim 1, wherein: The 3D network data of the optical cable includes the number, length, direction, attenuation coefficient of the optical cable, and the model, number, spatial coordinates, and attenuation coefficient of the optical splitter; it also includes the location of the known loss point in the optical cable and the attenuation coefficient of the loss point; The constructing of a topology diagram describing the optical cable connection specifically includes: marking any optical splitter as a node; Based on the actual connection status of the optical cable, each node is connected with an edge; attribute information is added to each node, including the model, number, and spatial coordinates of the splitter; attribute information is added to each edge, including the number, winding distance, routing direction, and attenuation coefficient of the optical cable segment corresponding to the edge, as well as the position of each known loss point in the optical cable and the attenuation coefficient of the loss point contained in the optical cable segment corresponding to the edge.

3. The method for locating a cable fault spatial position according to claim 2, wherein: The optical time domain reflection signal includes a reflection signal and a backscattered signal of the light pulse generated by the optical time domain reflectometer reflected in the optical cable; the fault point is the location where the fault occurs in the optical cable; the detection point is the location of the optical cable connected to the optical time domain reflectometer; The optical time domain reflectometer injects light pulses into the optical cable at the test point; The fault distance is the length of the optical cable between the fault point and the detection point; Calculating the fault distance between the fault point and the detection point based on the optical time domain reflectometry signal specifically includes: Identifying a fault waveform in the optical time domain reflectometer signal; recording a time delay value of the fault waveform; wherein the fault waveform is a segment of the optical time domain reflectometer signal reflected from the fault point; and the time delay value is the time difference between the moment when the optical time domain reflectometer injects an optical pulse into the optical cable and the moment when the fault waveform is received; The fault distance is calculated based on the time delay value and the propagation speed of the optical pulse in the optical cable.

4. A method for locating a cable fault spatial position according to claim 3, characterized in that: The fault path is a topological path between a potential fault point and the detection point in the topological map; the potential fault point is a point in the topological map where the length of the optical cable segment between the potential fault point and the detection point is equal to the fault distance; Exploring the fault path between the fault point and the detection point in the topology diagram specifically includes: Locating the detection point in the topology map; the detection point is an optical splitter, corresponding to a node in the topology map; In the topology diagram, starting from the detection point, exploration is carried out along the direction of the light pulse injected by the optical time domain reflectometer, and the exploration path is updated in real time. The length of the exploration path is calculated based on the winding distance of the optical cable segment corresponding to the edge involved in the exploration path. When the length of the exploration path reaches the fault distance, the exploration is stopped and the location where the exploration is stopped is marked as a potential fault point. The exploration path between any potential fault point and the detection point is the fault path corresponding to the potential fault point.

5. The method for locating a cable fault spatial position according to claim 4, wherein: Exploring the fault path between the fault point and the detection point in the topology map further includes: If the node corresponding to the spectrometer is passed during the exploration along the direction of the light pulse injected by the optical time domain reflectometer, the current length of the exploration path is recorded when passing the node corresponding to the spectrometer; the current length is the sum of the lengths corresponding to all edges contained in the exploration path between the detection point and the node corresponding to the spectrometer; the difference between the fault distance and the current length is calculated as the remaining fault distance; starting from the node corresponding to the spectrometer, the exploration is restarted along each edge connected to the node corresponding to the spectrometer, and the exploration path is updated in real time; when the length of the exploration path reaches the remaining fault distance, the exploration is stopped, and the location where the exploration is stopped is marked as a potential fault point.

6. The method for locating a cable fault spatial position according to claim 5, wherein: The attribute information corresponding to the fault path in the topology graph includes the number, winding distance, and routing direction of the optical cable segment corresponding to each edge involved in the fault path, and the number and spatial coordinates of the optical splitter corresponding to each node involved in the fault path; The spatial positioning of the fault point based on the attribute information of the corresponding fault path in the topology map specifically includes: Based on the edge of the potential fault point corresponding to the fault path in the topology graph, determine the number of the optical cable segment where the fault point is located; Mark the node closest to the potential fault point in the fault path as the upstream node of the potential fault point; calculate the length of the optical cable between the upstream node and the fault point; the difference between the fault distance and the sum of the coiled distances of the optical cable segments between the detection point and the upstream node is the length of the optical cable between the upstream node and the fault point; Record the location information of the spatial position of the fault point; the location information includes the number of the optical cable segment, the routing direction, the number and spatial coordinates of the upstream node, and the length of the optical cable between the upstream node and the fault point.

7. The method for locating a cable fault spatial position according to claim 6, wherein: The elements in the theoretical attenuation sequence are the attenuation coefficients at different locations of the optical cable in the fault path. The method for constructing the theoretical attenuation sequence for any fault path is as follows: Mark an attenuation exploration segment in the fault path; the starting point of the attenuation exploration segment is the detection point, the length of the optical cable between the end point and the starting point is D, and the potential fault point corresponding to the fault path is located between the detection point and the end point; Based on the attribute information of the edge, the position of the known loss point in the optical cable and the attenuation coefficient of the loss point in the attenuation exploration segment are obtained; each loss point is marked as a sampling point, and the attenuation coefficient of each sampling point is recorded; Supplementing sampling points in the attenuation exploration segment so that the supplemented sampling points are evenly distributed in the attenuation exploration segment; determining the attenuation coefficient of each supplemented sampling point based on the attribute information of the edge where each supplemented sampling point is located; The attenuation coefficients of all sampling points are sorted into the theoretical attenuation sequence of the fault path in the order from near to far from the potential fault point.

8. The method for locating a cable fault spatial position according to claim 7, wherein: The independent reflection envelope of any non-target path is calculated as follows: The theoretical attenuation sequence of the non-target path is converted into a continuous attenuation sequence function through linear interpolation; Convolving the attenuation sequence function with a time domain signal of an optical pulse injected into the optical cable by an optical time domain reflectometer to obtain an independent reflection envelope of a non-target path; The independent reflection envelope is subjected to amplitude correction based on the light splitting ratio of the non-target path.

9. The method for locating a cable fault spatial position according to claim 8, wherein: Calculating the credibility of the target fault path based on the target reflection envelope specifically includes: intercepting a segment after the fault waveform in the optical time domain reflectometer signal as a reference waveform segment; detecting waveform steps in the reference waveform segment and marking a timestamp for each waveform step; Based on the timestamp, it is detected whether each waveform step disappears in the target reflection envelope; and the number of waveform steps that disappear in the target reflection envelope is recorded as the credibility of the target fault path.

10. The method for locating a cable fault spatial position according to claim 1, wherein: The 3D network data is obtained based on the 3D model of the optical cable; the method for constructing the 3D model is as follows: Based on GIS geographic information data, use 3D modeling software to build a 3D basic framework of topography; Extract the optical cable location data from the GIS system, including the longitude and latitude coordinates, burial depth and elevation data of the optical cable path; Integrate the fiber optic cable node data collected on-site, including the location of the pipe well, the coordinates of the coiled area, the spatial coordinates of the splice box, and the length of the fiber optic cable; and construct a 3D model of the fiber optic cable, including: Based on the optical cable position data and the optical cable node data, the actual direction of the optical cable is fitted by a B-spline curve to achieve the marking of the spatial coordinates of the optical cable; The difference between the actual cable length and the straight-line distance in space is calculated using a spiral equation, and the number of coils and the coil diameter of the coil area are set based on the difference to achieve coil area modeling. 3D network data is organized and labeled for each section of optical cable in the 3D model; and the 3D model is integrated into a three-dimensional basic framework of the topography based on the spatial coordinates of the optical cables.

11. The method for locating a cable fault spatial position according to claim 10, wherein: The method further includes: spatially locating the fault point based on the fault distance and the 3D model, specifically including: Convert the 3D model of the optical cable into a weighted directed graph, where nodes represent cable connection points, edges represent cable segments, and the edge weight is the cable length; A heuristic search algorithm is used to find potential fault paths that match the fault distance in a weighted directed graph, and the potential fault points corresponding to each potential fault path are marked. Calculate the credibility of each potential fault path based on the fault prediction model, and retain the potential fault path with the highest credibility and the corresponding fault point; Based on spatial coordinates, the fault location and the optical cable direction of the potential fault path are visually marked in the 3D model.

Images