An optical fiber breakpoint searching method and device

Abstract

The application discloses an optical fiber breakpoint searching method and device, and relates to the technical field of optical fiber communication. The specific steps of the method are as follows: first, two paths of same-wavelength, symbol-level-synchronous code division multiplexing orthogonal coded detection light are generated, one path is narrow-pulse-width high-frequency coded light, and the other path is wide-pulse-width low-frequency coded light; then, the two paths of coded light are coupled to the same optical path and injected into the optical fiber to be detected; the returned back-reflection light is collected and converted into digital electrical signals which are homologous to the coding clock; the near-field and long-distance reflection signals are separated through orthogonal cross-correlation decoding; and the breakpoint position information is calculated and output after seamless splicing of the whole link. The narrow-pulse-width high-frequency coded light and the wide-pulse-width low-frequency coded light which are synchronously output in the same wavelength can realize the link coverage of the near-field non-blind area and the long-distance high dynamic range synchronously in a single detection, the splicing error caused by multiple detections is eliminated, and the detection efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of optical fiber communication technology, specifically to a method and apparatus for locating optical fiber breakpoints. Background Technology

[0002] Optical fiber communication is a core supporting technology for modern information transmission networks. With the large-scale deployment of computing networks, gigabit optical networks, and the industrial internet, the mileage of optical fiber cables continues to grow, and the link structure and laying scenarios are becoming increasingly complex and diverse. Optical time domain reflectometry (OTDR), as a core means of optical fiber link fault detection and performance monitoring, is widely used in key areas such as communication trunk lines, power dispatching, and rail transportation, and is a core foundational technology for ensuring the continuous and stable operation of optical communication networks. With the popularization of high-speed, high-capacity optical transmission systems, the industry has placed higher demands on the detection accuracy, coverage, and efficiency of optical fiber testing technologies.

[0003] Existing optical temporal reflectance detection schemes suffer from inherent technical contradictions that are difficult to reconcile. The pulse width of the probe light is strongly tied to the detection blind zone and dynamic range. Narrow pulse widths can reduce the detection blind zone but cannot cover long-distance links, while wide pulse widths can increase the detection distance but will expand the near-field blind zone. Existing solutions often use data stitching after multiple detections with different pulse widths, which results in low detection efficiency and large stitching errors. Dual-wavelength detection schemes require additional wavelength division multiplexing (WDM) devices, leading to high hardware costs. Algorithm compensation schemes can only fit and optimize the blind zone and cannot fundamentally solve the technical contradictions, making it difficult to balance detection accuracy, coverage, and detection efficiency. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a method and apparatus for locating fiber optic breakpoints. By generating code-division multiplexed dual-frequency orthogonal coded probe light of the same wavelength and symbol-level synchronization, combined with a positive cross-correlation decoding algorithm and seamless end-link splicing technology, a highly efficient and accurate fiber optic breakpoint location scheme is constructed. This overcomes the inherent contradiction between near-field blind zones and long-distance detection in traditional optical time-domain reflectometry, eliminating the need for multiple detections and splicings, achieving full-link coverage in a single operation. Through nanosecond-level timing synchronization, signal noise reduction, and loss compensation optimization, it accurately separates near-field and long-distance reflection signals, achieving dual location of the breakpoint fiber length and geographical coordinates, and can also distinguish multiple fault types. The solution is compatible with existing commercial equipment architectures, requiring no changes to the link structure, and is adaptable to various scenarios such as long-distance trunk lines and short-distance data center connections, effectively reducing maintenance thresholds and time costs, and improving the efficiency and accuracy of fiber optic fault detection.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: On one hand, a method for locating fiber optic breakpoints, the specific steps of which are as follows:

[0006] Orthogonal coding probe light generation: Generate two probe lights with code division multiplexing orthogonal coding characteristics. The two probe lights are optical signals with the same wavelength and synchronous output at the symbol level. The first probe light is a narrow pulse width high-frequency coded light, and the second probe light is a wide pulse width low-frequency coded light.

[0007] Probe optical coupling injection: Two orthogonally coded probe beams are coupled to the same optical path to maintain the orthogonality of the two optical signals and ensure that the synchronization timing is not distorted, and then injected into the optical fiber under test;

[0008] Reflection signal acquisition and conversion: Synchronously acquire the back-reflected optical signal returned by the fiber optic link under test, and after photoelectric conversion, convert the analog reflected signal into a digital electrical signal with the same source as the encoding generation clock;

[0009] Orthogonal decoding signal separation: Based on the positive cross-correlation decoding algorithm, orthogonal decoding operation is performed on the digital electrical signal to separate the near-field reflection signal corresponding to the first probe light and the long-distance reflection signal corresponding to the second probe light without crosstalk;

[0010] End-to-end splicing and breakpoint location: The near-field reflected signal and the long-distance reflected signal are seamlessly spliced ​​together. The location information of the breakpoint is calculated and output based on the continuous signal of the spliced ​​end-to-end.

[0011] Furthermore, in the orthogonal coding probe light generation step, the orthogonal coding used by the two probe lights is Walsh code or Gold code, and the cross-correlation coefficient of the two coding sequences is controlled to be zero when generating the coding sequence; the pulse width range of the first probe light is 10 nanoseconds to 100 nanoseconds, and the pulse width range of the second probe light is 1 microsecond to 10 microseconds; before generating the probe light, a link pre-scan is performed to obtain the link length, link loss and splitting ratio parameters of the optical fiber under test, and the coding sequence length, pulse width and transmitted light power of the two probe lights are adaptively adjusted based on the obtained link parameters.

[0012] Furthermore, in the orthogonal coding probe light generation step, the symbol rate of the coding sequence of the first probe light is not lower than the Nyquist sampling rate corresponding to its narrow pulse width, and the symbol rate of the coding sequence of the second probe light is matched with the wide pulse width parameter, so that the two coding sequences are respectively adapted to the pulse width characteristics of the corresponding probe light.

[0013] Furthermore, in the probe light coupling injection step, a single-mode fiber directional coupler is used to complete the co-optical coupling of the two probe lights. During the coupling process, the power ratio of the two probe lights is kept stable, and the echo noise generated by the coupled optical path is suppressed. In the process of generating the orthogonal encoded probe light to converting the reflected signal, the nanosecond-level time synchronization of the three actions of orthogonal encoding generation, optical signal transmission, and reflected signal acquisition is achieved through a global clock synchronization unit.

[0014] Furthermore, the positive cross-correlation decoding algorithm in the orthogonal decoding signal separation step specifically executes as follows:

[0015] The first step is to perform amplitude normalization on the digital electrical signal to convert it into a standardized digital sequence;

[0016] The second step is to perform cross-correlation operations between the standardized digital sequence and the original coded sequences corresponding to the two probe beams. The formula for cross-correlation is as follows: In the formula, Calculate the value for the cross-correlation function; This is the summation operator; =0 to The sampling point interval for the summation operation; This refers to the round-trip time delay corresponding to optical signal transmission. For the first The standardized digital sequence values ​​corresponding to each sampling point; For delay After time The total number of sampling points;

[0017] The third step is to extract the reflected signal components corresponding to the two probe beams based on the cross-correlation peak positions obtained by calculation, and filter out the crosstalk components between the two signals based on the orthogonality of the two coding sequences.

[0018] Furthermore, after separating the near-field reflection signal and the long-distance reflection signal in the orthogonal decoding signal separation step, wavelet denoising and gain matching processing are performed on the two reflection signals respectively. First, random noise and out-of-band interference in the acquisition process are eliminated by 5-layer db5 wavelet decomposition. Then, based on the link attenuation coefficient of the optical fiber under test, link loss compensation is performed on the long-distance reflection signal to unify the amplitude reference of the two reflection signals.

[0019] Furthermore, the seamless splicing of the entire link in the end-to-end splicing and breakpoint location step is specifically executed as follows:

[0020] The first step is to divide the link detection area, complete the near-field link detection within the range of 0 to 5 meters based on the near-field reflection signal, and complete the long-distance link detection within the range of 5 meters to the maximum detection distance based on the long-distance reflection signal. The maximum detection distance is the maximum detectable distance of the link corresponding to the second probe light.

[0021] The second step is to perform dual synchronous calibration of amplitude and phase on the overlapping section of the two signals within a range of 4 to 6 meters to eliminate the timing and amplitude deviations of the two signals.

[0022] The third step is to seamlessly stitch together the calibrated signals to generate a continuous reflection signal curve across the entire link.

[0023] Furthermore, the calculation of breakpoint location information in the end-to-end splicing and breakpoint location step is specifically performed as follows:

[0024] The first step is to identify Fresnel reflection abrupt change points in the reflection signal curve after the entire link is spliced, and record the round-trip time of the optical signal corresponding to the abrupt change point;

[0025] The second step is to calculate the fiber length from the breakpoint to the test end based on the group refractive index and the round-trip time of the optical signal. The calculation formula is as follows: In the formula, The distance from the breakpoint to the test end is the length of the optical fiber. The speed of light in a vacuum is constant. The round-trip time of the optical signal corresponding to the mutation point; is the nominal group refractive index of the optical fiber under test; the denominator value 2 is the path multiple corresponding to the round-trip transmission of the optical signal;

[0026] The third step is to combine the pre-stored geographical routing information of the fiber optic link, map the fiber length information of the breakpoint to the corresponding geographical coordinate information, and output the dual location information of the breakpoint: fiber length and geographical coordinates.

[0027] Furthermore, in the end-to-end splicing and breakpoint location steps, after generating a continuous reflection signal curve for the entire link, the characteristic patterns of amplitude abrupt change, slope change, and attenuation rate of the curve are extracted to distinguish the fault types of complete breakage, fiber core microcracks, connector loss, and macrobending loss, and the spatial location and loss value corresponding to each type of fault are output synchronously. After completing the breakpoint location, the breakpoint location, fault type, and link loss data are archived synchronously, and the encoding parameters, pulse width configuration, and decoding operation logic of the two probe beams are iteratively optimized based on the archived data.

[0028] On the other hand, there is a fiber optic breakpoint locating device, which includes an orthogonal encoding generation module, a light source driving module, an optical emission module, an optical coupling module, an optical receiving module, a signal acquisition module, an orthogonal decoding module, and a signal splicing and positioning module that are connected in sequence.

[0029] The orthogonal coding generation module is used to generate two coding sequences with code division multiplexing orthogonal coding characteristics, and synchronously outputs the two coding sequences to the light source driving module, while providing a unified timing reference for the entire device;

[0030] The light source driving module is used to drive the light emission module based on the input orthogonal coding sequence to generate two orthogonal coding probe lights with the same wavelength and synchronous output at the symbol level. The first probe light is a narrow pulse width high-frequency coding light, and the second probe light is a wide pulse width low-frequency coding light.

[0031] The optical emission module is used to output the generated orthogonal coded probe light to the optical coupling module;

[0032] The optical coupling module is used to couple two orthogonally coded probe beams to the same optical path and inject them into the fiber under test. At the same time, it collects the back-reflected optical signal returned by the fiber under test link and outputs it to the optical receiving module.

[0033] The optical receiving module is used to perform photoelectric conversion on the received reflected light signal and output an analog electrical signal to the signal acquisition module;

[0034] The signal acquisition module is used to convert the input analog electrical signal into a digital electrical signal that is from the same source as the encoding generation clock, and output it to the quadrature decoding module;

[0035] The orthogonal decoding module is used to perform orthogonal decoding on digital electrical signals based on the positive cross-correlation decoding algorithm, and separates the near-field reflection signal corresponding to the first probe light and the long-distance reflection signal corresponding to the second probe light without crosstalk, and outputs them to the signal splicing and positioning module.

[0036] The signal splicing and positioning module is used to complete the seamless splicing of near-field reflected signals and long-distance reflected signals across the entire link, and calculates and outputs the location information of the breakpoints based on the spliced ​​continuous signal across the entire link.

[0037] Compared with existing technologies, this fiber optic breakpoint locating method and apparatus has the following advantages:

[0038] I. This invention achieves near-field blind-zone-free and long-distance high dynamic range link coverage simultaneously with narrow-pulse-width high-frequency coded light and wide-pulse-width low-frequency coded light by synchronously outputting narrow-pulse-width coded light at the same wavelength in a single detection. This eliminates splicing errors caused by multiple detections, improves detection efficiency, and is directly compatible with the hardware architecture of existing commercial detection equipment. There is no need to replace the core optoelectronic components, resulting in low incremental hardware costs and adaptability to the detection needs of various fiber optic links.

[0039] II. This invention achieves precise location of fiber optic breakpoints and full-link fault identification through a full-process nanosecond-level timing synchronization mechanism and a link adaptive detection process, combined with a positive cross-correlation decoding algorithm and multi-dimensional signal calibration processing. This solution ensures encoding and decoding timing matching through co-source clock synchronization, effectively suppressing optical path crosstalk and environmental noise, improving the ability to identify weak reflected signals, accurately distinguishing multiple types of fiber optic faults, and simultaneously achieving dual location of the breakpoint's fiber length and geographical coordinates. This completes the adaptive closed-loop optimization of the detection process, reducing the operational threshold and time cost of fiber optic maintenance.

[0040] Other advantages, objectives and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination or study, or may be learned from the practice of the invention. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0042] Figure 1 This is an overall flowchart of the fiber optic breakpoint locating method of the present invention;

[0043] Figure 2 This is a flowchart of the positive cross-correlation decoding algorithm in the orthogonal decoding signal separation step of the present invention;

[0044] Figure 3 This is a flowchart of the signal splicing and breakpoint location process in the end-to-end splicing and breakpoint location steps of the present invention. Detailed Implementation

[0045] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0046] Example 1:

[0047] This embodiment discloses a fiber optic breakpoint location method applied to a single-mode fiber optic link in a carrier's backbone fiber optic transmission network. The link is 120 kilometers long and includes both direct burial and overhead installation methods, with multiple fusion splices and junction boxes along its length. This embodiment is based on a code-division multiplexing dual-frequency orthogonal coding probe optical architecture. By using narrow-pulse-width high-frequency coded light and wide-pulse-width low-frequency coded light output synchronously at the same wavelength, combined with a positive cross-correlation decoding algorithm, a single detection completes full-link coverage without blind spots, achieving accurate location of fiber optic breakpoints and full-link fault identification, thus adapting to the maintenance and testing needs of long-distance trunk fiber optics.

[0048] like Figure 1 As shown, the overall process of this embodiment includes orthogonal coding probe light generation, probe light coupling injection, reflection signal acquisition and conversion, orthogonal decoding signal separation, full-link splicing and breakpoint location.

[0049] After starting the testing process, a link pre-scan is first performed. Low-power, wide-pulse-width probe light is injected into the fiber under test to complete a rapid full-link scan and obtain the total link length, total link loss, and link splitting ratio parameters of the fiber under test.

[0050] Based on the acquired link parameters, the coding sequence length, pulse width, and transmit power of the two probe beams are adaptively adjusted. For a long-distance link of 120 kilometers, the coding sequence length is set to 64 bits, the pulse width of the first probe beam is set to 50 nanoseconds, the pulse width of the second probe beam is set to 5 microseconds, and the transmit power is uniformly set to 0dBm, which meets the human eye safety standards for fiber optic testing.

[0051] Then, an orthogonal coding sequence is generated, using Walsh code as the orthogonal coding base code, to generate two completely orthogonal coding sequences, and the cross-correlation coefficient of the two coding sequences is controlled to be zero.

[0052] Simultaneously, the coding sequence symbol rate of the first probe light is matched to 20 MHz, which is no less than the Nyquist sampling rate corresponding to the narrow pulse width. The coding sequence symbol rate of the second probe light is matched to 200 kHz, which is fully adapted to the wide pulse width parameter. Finally, two probe lights with the same wavelength and synchronous output at the symbol level are generated. The light wavelength is set to 1550 nm, which is adapted to the low-loss transmission window of long-distance optical fiber links.

[0053] After the probe light is generated, the probe light coupling injection operation is performed. A single-mode fiber directional coupler is used to couple the two probe lights in the same optical path. The coupler operates at wavelengths covering 1310 nm and 1550 nm, and the splitting ratio is set to 10:90. The 10 ratio port is connected to the output of the optical transmitter module, and the 90 ratio port is connected to the fiber optic link under test. During the coupling process, the power ratio of the two probe lights is kept stable in real time, while the echo noise generated by the coupled optical path is suppressed to avoid the echo noise interfering with the near-field reflection signal.

[0054] After coupling, the probe light maintains orthogonal characteristics and synchronization timing without distortion, and is fully injected into the fiber optic link under test. At the same time, through the global clock synchronization unit, nanosecond-level time synchronization of the three actions of orthogonal encoding generation, optical signal transmission, and reflected signal acquisition is achieved, with synchronization accuracy controlled within ±50 nanoseconds, providing a unified timing reference for subsequent encoding and decoding operations.

[0055] Subsequently, a reflection signal acquisition and conversion operation is performed. The back-reflected light signal returned by the fiber optic link under test is synchronously acquired through the reverse output port of the fiber optic directional coupler. The reflected light signal includes Rayleigh scattering signal and Fresnel reflection signal.

[0056] The collected reflected light signal is input to a photodetector to complete photoelectric conversion and generate an analog electrical signal corresponding to the light signal intensity. The analog electrical signal is then sampled by a high-speed analog-to-digital converter with a sampling rate of 1 gigahertz. The sampling process is kept completely in sync with the encoding generation clock. Finally, the analog reflected signal is converted into a digital electrical signal and output to the subsequent decoding processing unit.

[0057] After signal acquisition and conversion, orthogonal decoding is performed on the digital electrical signal based on the positive cross-correlation decoding algorithm, such as... Figure 2 As shown, the specific execution process of this algorithm consists of three steps:

[0058] The first step is to perform amplitude normalization processing on the digital electrical signal. The maximum and minimum value normalization method is used to uniformly map the amplitude range of the digital electrical signal to the interval between 0 and 1, converting it into a standardized digital sequence and eliminating the impact of signal amplitude fluctuations on subsequent calculations.

[0059] The second step involves performing cross-correlation operations between the standardized digital sequence and the original coded sequences corresponding to the two probe beams. The formula for calculating the cross-correlation operation is as follows: In the formula, Calculate the value for the cross-correlation function; This is the summation operator; =0 to The sampling point interval for the summation operation; This refers to the round-trip time delay corresponding to optical signal transmission. For the first The standardized digital sequence values ​​corresponding to each sampling point; For delay After time The total number of sampling points.

[0060] The third step involves extracting the reflection signal components corresponding to the two probe beams based on the calculated cross-correlation peak positions. Then, using the orthogonality of the two coding sequences as a basis, the crosstalk components between the two signals are filtered out, and finally, the near-field reflection signal corresponding to the first probe beam and the long-distance reflection signal corresponding to the second probe beam are obtained without crosstalk.

[0061] After obtaining the two reflected signals, wavelet denoising and gain matching are performed on the two reflected signals respectively. First, the reflected signals are decomposed and reconstructed in multiple layers by 5-layer db5 wavelet decomposition to eliminate random noise and out-of-band interference during the acquisition process. Then, based on the link attenuation coefficient of the optical fiber under test, link loss compensation is performed on the long-distance reflected signal to unify the amplitude reference of the two reflected signals and eliminate the amplitude deviation caused by link transmission attenuation.

[0062] After signal separation and preprocessing, perform end-to-end splicing and breakpoint location operations, such as... Figure 3 As shown, this operation includes two parts: seamless end-to-end stitching and breakpoint location information calculation. The specific process is as follows: First, seamless end-to-end stitching is performed, which consists of three steps:

[0063] The first step is to divide the link detection area. Near-field link detection is completed within a range of 0 to 5 meters based on near-field reflection signals, and long-distance link detection is completed within a range of 5 meters to 120 kilometers based on long-distance reflection signals. The maximum detection distance is consistent with the maximum detectable distance of the link corresponding to the second probe light.

[0064] The second step is to perform dual synchronous calibration of amplitude and phase in the overlapping section of the two signals within a range of 4 to 6 meters. Using the timing of the near-field reflected signal as a reference, the phase offset of the long-distance reflected signal is adjusted, and the amplitude reference of the two signals is unified to eliminate the timing and amplitude deviations of the two signals.

[0065] The third step involves seamlessly stitching the calibrated signals to generate a continuous reflection signal curve across the entire link.

[0066] After the signal splicing is completed, the breakpoint location information is calculated. The specific process consists of three steps:

[0067] The first step is to identify Fresnel reflection abrupt change points in the reflection signal curve after the entire link is spliced, and record the round-trip time of the optical signal corresponding to the abrupt change point.

[0068] The second step is to calculate the fiber length from the breakpoint to the test end based on the group refractive index and the round-trip time of the optical signal. The calculation formula is as follows: In the formula, The distance from the breakpoint to the test end is the length of the optical fiber. The speed of light in a vacuum is constant. The round-trip time of the optical signal corresponding to the mutation point; is the nominal group refractive index of the optical fiber under test; the denominator value 2 is the path multiple corresponding to the round-trip transmission of the optical signal.

[0069] The third step involves combining the pre-stored geographical routing information of the fiber optic link with the fiber optic length information of the breakpoint to map the corresponding geographical coordinate information, and outputting the dual location information of the breakpoint: fiber optic length and geographical coordinates.

[0070] After generating a continuous reflection signal curve for the entire link, the characteristics of amplitude abrupt change, slope change, and attenuation rate of the curve are extracted to distinguish the fault types of complete breakage, fiber core microcrack, connector loss, and macrobending loss, and the spatial location and loss value corresponding to each type of fault are output synchronously.

[0071] After completing the breakpoint location, the breakpoint location, fault type, and link loss data are archived synchronously. Based on the archived data, the encoding parameters, pulse width configuration, and decoding operation logic of the two probe beams are iteratively optimized to achieve adaptive closed-loop optimization of the detection process.

[0072] This embodiment addresses the detection requirements of long-distance backbone fiber optic links, fully implementing a synchronous detection process using dual-frequency orthogonal coded probe light. A single detection can achieve full coverage of a 120-kilometer link, with the near-field detection blind zone controlled within 0.5 meters and the breakpoint positioning error controlled within ±1 meter. This effectively solves the problems of large near-field blind zones and low efficiency of multiple detections in traditional long-distance detection solutions. This embodiment is directly compatible with the hardware architecture of existing commercial optical time-domain reflectometry (OTDR) equipment, requiring no modification to the existing fiber optic link structure, and can be directly applied to routine maintenance and fault repair scenarios of backbone networks.

[0073] Example 2:

[0074] This embodiment discloses a fiber optic breakpoint location method applied to a high-density fiber optic cabling system in a data center. The link under test is a single-mode fiber optic patch cord link from a data center TOR switch to a storage device, with a total length of 80 meters. The link includes four fiber optic connectors and two fusion splices, and the entire link is located within the server racks and cable trays in the data center. This embodiment is based on a code division multiplexing dual-frequency orthogonal coding probing optical architecture, focusing on optimizing near-field high-resolution detection capabilities. It eliminates near-field blind spots through a positive cross-correlation decoding algorithm, achieving accurate breakpoint location and connector loss detection for short-distance links in the data center, thus meeting the maintenance and testing requirements of high-density fiber optics in data centers.

[0075] After starting the testing process, a link pre-scan is first performed. Low-power, narrow-pulse probe light is injected into the fiber under test to complete a rapid full-link scan and obtain the total link length, total link loss, number of link connectors, and splitting ratio parameters of the fiber under test.

[0076] Based on the acquired link parameters, the coding sequence length, pulse width, and transmit power of the two probe beams are adaptively adjusted. For the 80-meter short-range data center link, the coding sequence length is set to 32 bits, the pulse width of the first probe beam is set to 10 nanoseconds, the pulse width of the second probe beam is set to 1 microsecond, and the transmit power is uniformly set to -5dBm to adapt to the low-power detection requirements of the short-range data center link.

[0077] Then, an orthogonal coding sequence is generated, using Gold code as the orthogonal coding base code, to generate two completely orthogonal coding sequences, and the cross-correlation coefficient of the two coding sequences is controlled to be zero.

[0078] Simultaneously, the coding sequence symbol rate of the first probe light is matched to 100 MHz, which is no less than the Nyquist sampling rate corresponding to the narrow pulse width. The coding sequence symbol rate of the second probe light is matched to 1 MHz, which is fully adapted to the wide pulse width parameter. Finally, two probe lights with the same wavelength and synchronous output at the symbol level are generated. The light wavelength is set to 1310 nanometers to adapt to the transmission characteristics of the short-distance fiber optic link in the computer room.

[0079] After the probe light is generated, the probe light coupling injection operation is performed. A single-mode fiber directional coupler is used to couple the two probe lights in the same optical path. The coupler operates at wavelengths covering 1310 nm and 1550 nm, and the splitting ratio is set to 10:90. The 10 ratio port is connected to the output of the optical transmitter module, and the 90 ratio port is connected to the fiber optic link under test. During the coupling process, the power ratio of the two probe lights is kept stable in real time, while the echo noise generated by the coupled optical path is suppressed to avoid the echo noise interfering with the near-field reflection signal of the short-distance link in the equipment room.

[0080] After coupling, the probe light maintains orthogonal characteristics and synchronization timing without distortion, and is fully injected into the fiber optic link under test. At the same time, through the global clock synchronization unit, nanosecond-level time synchronization of the three actions of orthogonal encoding generation, optical signal transmission, and reflected signal acquisition is achieved, with synchronization accuracy controlled within ±20 nanoseconds. This provides a unified timing reference for subsequent encoding and decoding operations and ensures accurate acquisition of near-field signals.

[0081] Subsequently, a reflection signal acquisition and conversion operation is performed. The back-reflected light signal returned by the fiber optic link under test is synchronously acquired through the reverse output port of the fiber optic directional coupler. The reflected light signal includes Rayleigh scattering signal and Fresnel reflection signal.

[0082] The collected reflected light signal is input into a photodetector to complete photoelectric conversion and generate an analog electrical signal corresponding to the light signal intensity.

[0083] The analog electrical signal is then sampled by a high-speed analog-to-digital converter with a sampling rate of 2 GHz to improve the sampling resolution of the near-field signal. The sampling process is completely synchronized with the encoding generation clock. Finally, the analog reflected signal is converted into a digital electrical signal and output to the subsequent decoding processing unit.

[0084] After signal acquisition and conversion are completed, orthogonal decoding is performed on the digital electrical signal based on the positive cross-correlation decoding algorithm. The specific execution process consists of three steps:

[0085] The first step is to perform amplitude normalization processing on the digital electrical signal. The maximum and minimum value normalization method is used to uniformly map the amplitude range of the digital electrical signal to the interval between 0 and 1, convert it into a standardized digital sequence, and eliminate the influence of signal amplitude fluctuations on subsequent calculations.

[0086] The second step is to perform cross-correlation operations between the standardized digital sequence and the original coded sequences corresponding to the two probe beams, respectively.

[0087] The third step involves extracting the reflection signal components corresponding to the two probe beams based on the calculated cross-correlation peak positions. Then, using the orthogonality of the two coding sequences as a basis, the crosstalk components between the two signals are filtered out, and finally, the near-field reflection signal corresponding to the first probe beam and the long-distance reflection signal corresponding to the second probe beam are obtained without crosstalk.

[0088] After obtaining the two reflected signals, wavelet denoising and gain matching are performed on the two reflected signals respectively. First, the reflected signals are decomposed and reconstructed in multiple layers by 5-layer dB5 wavelet decomposition to eliminate random noise and out-of-band interference caused by the electromagnetic environment of the computer room. Then, based on the link attenuation coefficient of the optical fiber under test, link loss compensation is performed on the long-distance reflected signal to unify the amplitude reference of the two reflected signals and eliminate the amplitude deviation caused by link transmission attenuation.

[0089] After signal separation and preprocessing, the end-to-end splicing and breakpoint location operations are performed. First, the end-to-end seamless splicing is performed, which consists of three steps:

[0090] The first step is to divide the link detection area. Based on the near-field reflection signal, the near-field link detection is completed within a range of 0 to 5 meters, covering the short-distance jumper section from the equipment port in the computer room to the cable tray in the cabinet. Based on the long-distance reflection signal, the long-distance link detection is completed within a range of 5 to 80 meters. The maximum detection distance is consistent with the maximum detectable distance of the link corresponding to the second detection light.

[0091] The second step is to perform dual synchronous calibration of amplitude and phase in the overlapping section of the two signals within a range of 4 to 6 meters. Using the timing of the near-field reflected signal as a reference, the phase offset of the long-distance reflected signal is adjusted, and the amplitude reference of the two signals is unified to eliminate the timing and amplitude deviations of the two signals.

[0092] The third step involves seamlessly stitching the calibrated signals to generate a continuous reflection signal curve across the entire link.

[0093] After the signal splicing is completed, the breakpoint location information is calculated. The specific process consists of three steps:

[0094] The first step is to identify Fresnel reflection abrupt change points in the reflection signal curve after the entire link is spliced, and record the round-trip time of the optical signal corresponding to the abrupt change point;

[0095] The second step is to calculate the fiber length from the breakpoint to the test end based on the group refractive index and the round-trip time of the optical signal.

[0096] The third step involves combining the pre-stored geographical routing information of the computer room cabling in the fiber optic link to map the fiber optic length information of the breakpoint to the corresponding cabinet number, port location, and cable tray routing information, and outputting the dual location information of the breakpoint: fiber optic length and physical location.

[0097] After generating a continuous reflection signal curve for the entire link, the characteristics of amplitude abrupt change, slope change, and attenuation rate of the curve are extracted to distinguish the fault types of complete breakage, fiber core microcrack, connector loss, and macrobending loss. The spatial location and loss value corresponding to each type of fault are output synchronously, and the connector loosening and fiber skipping bending faults that occur frequently in the data center link are identified as the key faults.

[0098] After completing the breakpoint location, the breakpoint location, fault type, and link loss data are archived synchronously. Based on the archived data, the encoding parameters, pulse width configuration, and decoding operation logic of the two probe beams are iteratively optimized to achieve adaptive closed-loop optimization of the detection process.

[0099] This embodiment addresses the detection needs of short-distance, high-density fiber optic links in data center server rooms by optimizing near-field high-resolution detection capabilities. The near-field detection blind zone can be controlled within 0.3 meters, and the breakpoint location error can be controlled within ±0.2 meters. It can accurately identify breakpoints and connector degradation faults in short-distance jumpers within server racks, solving the problem of insufficient near-field blind zone and minor fault identification capabilities in traditional detection solutions. This embodiment can be directly embedded into existing fiber optic operation and maintenance management systems in data centers without modifying the server room cabling structure, adapting to the daily operation and maintenance and rapid fault diagnosis needs of high-density fiber optic scenarios.

[0100] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for locating fiber optic breakpoints, characterized in that, The specific steps of this method are as follows: Orthogonal coding probe light generation: Generate two probe lights with code division multiplexing orthogonal coding characteristics. The two probe lights are optical signals with the same wavelength and synchronous output at the symbol level. The first probe light is a narrow pulse width high-frequency coded light, and the second probe light is a wide pulse width low-frequency coded light. Probe optical coupling injection: Two orthogonally coded probe beams are coupled to the same optical path to maintain the orthogonality of the two optical signals and ensure that the synchronization timing is not distorted, and then injected into the optical fiber under test; Reflection signal acquisition and conversion: Synchronously acquire the back-reflected optical signal returned by the fiber optic link under test, and after photoelectric conversion, convert the analog reflected signal into a digital electrical signal with the same source as the encoding generation clock; Orthogonal decoding signal separation: Based on the positive cross-correlation decoding algorithm, orthogonal decoding operation is performed on the digital electrical signal to separate the near-field reflection signal corresponding to the first probe light and the long-distance reflection signal corresponding to the second probe light without crosstalk; End-to-end splicing and breakpoint location: The near-field reflected signal and the long-distance reflected signal are seamlessly spliced ​​together. The location information of the breakpoint is calculated and output based on the continuous signal of the spliced ​​end-to-end.

2. The fiber optic breakpoint location method according to claim 1, characterized in that, In the orthogonal coding probe light generation step, the orthogonal coding used by the two probe lights is Walsh code or Gold code, and the cross-correlation coefficient of the two coding sequences is controlled to be zero when generating the coding sequence; the pulse width range of the first probe light is 10 nanoseconds to 100 nanoseconds, and the pulse width range of the second probe light is 1 microsecond to 10 microseconds; before generating the probe light, a link pre-scan is performed to obtain the link length, link loss and splitting ratio parameters of the optical fiber under test, and the coding sequence length, pulse width and transmitted light power of the two probe lights are adaptively adjusted based on the obtained link parameters.

3. The fiber optic breakpoint location method according to claim 1, characterized in that, In the orthogonal coding probe light generation step, the symbol rate of the coding sequence of the first probe light is not lower than the Nyquist sampling rate corresponding to its narrow pulse width, and the symbol rate of the coding sequence of the second probe light is matched with the wide pulse width parameter, so that the two coding sequences are respectively adapted to the pulse width characteristics of the corresponding probe light.

4. The fiber optic breakpoint location method according to claim 1, characterized in that, In the probe light coupling injection step, a single-mode fiber directional coupler is used to complete the co-optical coupling of the two probe lights. During the coupling process, the power ratio of the two probe lights is kept stable, and the echo noise generated by the coupled optical path is suppressed. In the process of generating the orthogonal encoded probe light to converting the reflected signal, the nanosecond-level time synchronization of the three actions of orthogonal encoding, optical signal transmission, and reflected signal acquisition is achieved through a global clock synchronization unit.

5. The fiber optic breakpoint location method according to claim 1, characterized in that, The positive cross-correlation decoding algorithm in the orthogonal decoding signal separation step is specifically executed as follows: The first step is to perform amplitude normalization on the digital electrical signal to convert it into a standardized digital sequence; The second step is to perform cross-correlation operations between the standardized digital sequence and the original coded sequences corresponding to the two probe beams. The formula for cross-correlation is as follows: In the formula, Calculate the value for the cross-correlation function; The summation operator; n = 0 to The sampling point interval for the summation operation; This refers to the round-trip time delay corresponding to optical signal transmission. For the first The standardized digital sequence values ​​corresponding to each sampling point; For delay After time The total number of sampling points; The third step is to extract the reflected signal components corresponding to the two probe beams based on the cross-correlation peak positions obtained by calculation, and filter out the crosstalk components between the two signals based on the orthogonality of the two coding sequences.

6. The fiber optic breakpoint location method according to claim 1, characterized in that, In the orthogonal decoding signal separation step, after separating the near-field reflection signal and the long-distance reflection signal, wavelet denoising and gain matching processing are performed on the two reflection signals respectively. First, random noise and out-of-band interference in the acquisition process are eliminated by 5-layer db5 wavelet decomposition. Then, based on the link attenuation coefficient of the optical fiber under test, link loss compensation is performed on the long-distance reflection signal to unify the amplitude reference of the two reflection signals.

7. The fiber optic breakpoint location method according to claim 1, characterized in that, The seamless splicing of the entire link in the end-to-end splicing and breakpoint location steps is specifically executed as follows: The first step is to divide the link detection area, complete the near-field link detection within the range of 0 to 5 meters based on the near-field reflection signal, and complete the long-distance link detection within the range of 5 meters to the maximum detection distance based on the long-distance reflection signal. The maximum detection distance is the maximum detectable distance of the link corresponding to the second probe light. The second step is to perform dual synchronous calibration of amplitude and phase on the overlapping section of the two signals within a range of 4 to 6 meters to eliminate the timing and amplitude deviations of the two signals. The third step is to seamlessly stitch together the calibrated signals to generate a continuous reflection signal curve across the entire link.

8. The fiber optic breakpoint location method according to claim 1, characterized in that, The calculation of breakpoint location information in the end-to-end splicing and breakpoint location step is specifically executed as follows: The first step is to identify Fresnel reflection abrupt change points in the reflection signal curve after the entire link is spliced, and record the round-trip time of the optical signal corresponding to the abrupt change point; The second step is to calculate the fiber length from the breakpoint to the test end based on the group refractive index and the round-trip time of the optical signal. The calculation formula is as follows: In the formula, The distance from the breakpoint to the test end is the length of the optical fiber. The speed of light in a vacuum is constant. The round-trip time of the optical signal corresponding to the mutation point; is the nominal group refractive index of the optical fiber under test; the denominator value 2 is the path multiple corresponding to the round-trip transmission of the optical signal; The third step is to combine the pre-stored geographical routing information of the fiber optic link, map the fiber length information of the breakpoint to the corresponding geographical coordinate information, and output the dual location information of the breakpoint: fiber length and geographical coordinates.

9. The fiber optic breakpoint location method according to claim 1, characterized in that, In the end-to-end splicing and breakpoint location steps, after generating a continuous reflection signal curve for the entire link, the amplitude abrupt change, slope change, and attenuation rate characteristics of the curve are extracted to distinguish the fault types of complete breakage, fiber core microcracks, connector loss, and macrobending loss. The spatial location and loss value corresponding to each type of fault are output synchronously. After the breakpoint location is completed, the breakpoint location, fault type, and link loss data are archived synchronously. Based on the archived data, the encoding parameters, pulse width configuration, and decoding operation logic of the two probe beams are iteratively optimized.

10. A fiber optic breakpoint locating device, applicable to the fiber optic breakpoint locating method according to any one of claims 1-9, characterized in that, The device includes an orthogonal encoding generation module, a light source driving module, a light emission module, an optical coupling module, a light receiving module, a signal acquisition module, an orthogonal decoding module, and a signal splicing and positioning module, which are connected in sequence. The orthogonal coding generation module is used to generate two coding sequences with code division multiplexing orthogonal coding characteristics, and synchronously outputs the two coding sequences to the light source driving module, while providing a unified timing reference for the entire device; The light source driving module is used to drive the light emission module based on the input orthogonal coding sequence to generate two orthogonal coding probe lights with the same wavelength and synchronous output at the symbol level. The first probe light is a narrow pulse width high-frequency coding light, and the second probe light is a wide pulse width low-frequency coding light. The optical emission module is used to output the generated orthogonal coded probe light to the optical coupling module; The optical coupling module is used to couple two orthogonally coded probe beams to the same optical path and inject them into the fiber under test. At the same time, it collects the back-reflected optical signal returned by the fiber under test link and outputs it to the optical receiving module. The optical receiving module is used to perform photoelectric conversion on the received reflected light signal and output an analog electrical signal to the signal acquisition module; The signal acquisition module is used to convert the input analog electrical signal into a digital electrical signal that is from the same source as the encoding generation clock, and output it to the quadrature decoding module; The orthogonal decoding module is used to perform orthogonal decoding on digital electrical signals based on the positive cross-correlation decoding algorithm, and separates the near-field reflection signal corresponding to the first probe light and the long-distance reflection signal corresponding to the second probe light without crosstalk, and outputs them to the signal splicing and positioning module. The signal splicing and positioning module is used to complete the seamless splicing of near-field reflected signals and long-distance reflected signals across the entire link, and calculates and outputs the location information of the breakpoints based on the spliced ​​continuous signal across the entire link.

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