73 results about "Optical time-domain reflectometer" patented technology

The invention provides an optical fiber detection method and system for an optical time domain reflectometer, and relates to the technical field of power grids. According to the invention, the multi-wavelength backscattering signal of the optical fiber link to be detected is acquired, preprocessed and converted into the sample to be detected containing the multi-wavelength one-dimensional waveform data and the multi-wavelength two-dimensional diagram data at the same time, so that the sequence characteristic of the light intensity of each wavelength changing along with time is reserved; and spatial features of correlation and structural information between wavelengths can be reflected through data conversion construction, and multi-dimensional and structured representation of optical fiber events is realized. And combined analysis and recognition are carried out by combining a fault recognition model, and a time sequence rule in a one-dimensional waveform and a spatial distribution mode in a two-dimensional diagram are cooperatively mined, so that deep fusion and intelligent analysis of optical fiber fault spatial-temporal characteristics are realized, and the recognition capability of a complex fault mode is improved. The technical problem of low accuracy of optical fiber fault detection with a single wavelength at present is solved, and the accuracy and reliability of optical cable line fault detection are improved.

The invention discloses an interference fading point compensation method for a coherent phi-OTDR (Optical Time Domain Reflectometer), which comprises the following steps of: identifying an interference fading point on the basis of complex envelope characteristics obtained by coherent receiving and I / Q (Input / Output) demodulation, and performing interpolation reconstruction on a fading point echo vector by using a neighborhood non-fading point on a complex plane, so as to recalculate a phase and a differential phase; therefore, phase demodulation failure and differential phase artifacts caused by fading can be suppressed. According to the method, on the premise of not increasing hardware transformation, differential phase artifacts and abnormal stripes caused by phase demodulation failure at a fading point are reduced, the stability of a differential phase result and event identifiability are improved, and relatively low calculation complexity is kept to adapt to offline or quasi-real-time processing.

The application provides a phase-sensitive optical time domain reflectometer, a measurement method and a readable storage medium, wherein a signal generation circuit of the phase-sensitive optical time domain reflectometer is configured to generate a radio frequency signal to drive an optical intensity modulator to modulate probe light, so that two groups of frequency division multiplexing sequences with differences can be used to synchronously detect a sensing optical fiber to be measured, a differential unfolding algorithm is combined to accurately solve a phase change amount in adjacent sampling intervals, and then demodulation results corresponding to different frequency parts are respectively unfolded to obtain unfolded phase results, so that the problem of large strain phase folding is solved and a large strain range is recovered, and further, the unfolded phase results are rearranged and combined in time sequence through time sequence interleaving processing of the unfolded phase results, so that a high sampling rate and a distortion-free reconstruction result are reconstructed, and therefore, the application can realize accurate measurement of high frequency response and large strain range dynamic strain.

The invention discloses a BOTDR (Brillouin Optical Time Domain Reflectometer)-based OPGW (Optical Fiber Composite Overhead Ground Wire) light icing identification method, which comprises the following steps of: firstly, establishing a thermal conduction model of an OPGW in a non-icing state and an icing state, and constructing a theoretical expression of an OPGW icing thermal hysteresis effect by utilizing a linear relation between Brillouin frequency shift and temperature; then, the Brillouin frequency shift distribution along the line is obtained through a BOTDR system, actually measured data is matched with a model calculation result, and the icing thickness and the distribution interval are obtained through a regularization least square inversion method. According to the invention, clear identification of the light icing section can be realized, and good stability can be maintained under different illumination radiation intensity conditions. The method is clear in mechanism, high in model precision and suitable for early icing identification and anti-icing and deicing early warning application of the long-distance OPGW line.

A kind of distributed multi-parameter sensing system based on multi-core optical fiber, including laser, laser light source is sent to the signal generator input trigger pulse drive respectively with the signal input end of phase-sensitive optical time domain reflectometer based on Rayleigh scattering and its demodulation device, Raman optical time domain reflectometer based on Raman scattering and its demodulation device, Brillouin optical time domain reflectometer based on Brillouin scattering and its demodulation device are connected, the signal output end of phase-sensitive optical time domain reflectometer and its demodulation device, Raman optical time domain reflectometer and its demodulation device, Brillouin optical time domain reflectometer and its demodulation device is connected with the signal input end of multi-core optical fiber through multi-core optical fiber fan-in fan-out module;The present application utilizes the principle of space division multiplexing, each fiber core in optical cable as separate sensing channel carries out measurement and signal transmission;Multi-core optical fiber fuses three kinds of distributed optical fiber sensing systems together, realizes in-situ measurement and mutual compensation decoupling of temperature, strain and vibration, improves the measurement precision of sensing system.

1. Name of the product in this design: Optical Time Domain Reflectometer (Simplified Version). 2. Purpose of this design: For testing fiber optic signals. 3. The key design feature of this product is its shape. 4. The image or photograph that best illustrates the design's key points: a 3D model.

The invention belongs to the field of distributed optical fiber sensing and coding and decoding, and provides a Brillouin optical time domain reflection signal decoding method and system based on rising edge assistance. The rising edge assistance-based Brillouin optical time domain reflection signal decoding method comprises the following steps: acquiring a time domain coding response signal corresponding to a coding pulse sequence injected into an optical fiber by a Brillouin optical time domain reflectometer; performing discrete Fourier transform on the time domain coding response signal to obtain a frequency domain coding response signal; according to the signal increment and the duration of the rising edge of the time domain coding response signal, reconstructing a decoding function and replacing the decoding function in the frequency domain coding response signal with the reconstructed decoding function; the decoding function is a sequence formed by a decoding weight corresponding to each code element; and performing inverse discrete Fourier transform on the frequency domain coding response signal to obtain a decoded signal. According to the method, the signal-to-noise ratio of the decoded SpBS signal can be remarkably improved, and the Brillouin frequency shift (BFS) extraction precision is enhanced.

The invention provides a mine underground distributed optical fiber acoustic sensing system coupling construction method, and relates to the technical field of construction. Comprising the steps of sensing optical fiber routing design and optimal route and construction mode planning; carrying out base surface treatment and grooving at the included angle between the roadway bottom plate and the side wall; cleaning float coal in the groove, applying a coupling agent with a certain thickness on the bottom plate, and lightly pressing the sensing optical fiber into the coupling agent; covering the upper part of the optical fiber with a coupling agent until the groove is full, and applying pressure to ensure that the coupling agent is fully extruded to be tightly coupled with the coal (rock) body and the optical fiber; and finally, testing optical fiber loss by using an OTDR (Optical Time Domain Reflectometer), and carrying out field knocking detection by using a DAS host. According to the invention, the acoustic binding of the sensing optical fiber and the coal rock mass is realized through the two layers of high-damping coupling agents, and the transmission efficiency and the signal-to-noise ratio of a vibration signal are greatly improved; in addition, a quantifiable and verifiable construction process is provided, and consistency and reliability of monitoring data of different engineering sections are guaranteed.

The invention relates to the field of optical fiber pipeline monitoring, in particular to a safety monitoring method and equipment for an optical fiber pipeline and a medium, and the method comprises the steps that an unmanned aerial vehicle carries an optical time domain reflectometer and environment monitoring equipment to fly along the pipeline, and reflected light information and environment parameters such as temperature, humidity, air pressure and flight relative height are synchronously obtained. And after an initial leakage position is determined based on the reflected light information, an adaptive leakage position correction model is selected from a preset reference table according to the environmental parameters corresponding to the position. And the offset is calculated by substituting the environmental parameters into the correction model, and the target leakage position is obtained. According to the method, multi-source data fusion and a precise correction model are utilized, interference of environmental factors on positioning is effectively eliminated, the precision and reliability of optical fiber pipeline leakage positioning are remarkably improved, and the method is suitable for a pipeline safety monitoring scene in a complex environment.

The invention relates to an optical fiber link fault diagnosis method and device, computer equipment, a readable storage medium and a program product. The method comprises the following steps: acquiring a time domain power fluctuation characteristic of the optical fiber link through an intelligent optical module, and acquiring a space domain performance fluctuation characteristic of the optical fiber link through an optical time domain reflectometer; fusing the time domain power fluctuation feature and the space domain performance fluctuation feature to obtain a fused fluctuation feature; and determining a fault diagnosis result of the optical fiber link according to the fusion fluctuation characteristics. By adopting the method, the fault diagnosis efficiency of the optical fiber link can be improved.

The application provides a blind person discrimination device, system and method based on a distributed optical fiber sensing device.The device comprises an optical time domain reflectometer module, a signal preprocessing module, a signal cutting module, a signal feature extraction module and a signal classification module.The method provides a high recognition rate without video monitoring equipment and wearable sensing equipment, more comprehensively and effectively provides application support for the field of security and blind person travel, enhances the adaptability for different human body recognition, and identifies the source of the human body walking signal accepted by the current device, whether it is a visually impaired user or a normal user, so as to provide related services for the visually impaired user in the future.The long-time and short-time feature joint recognition mode is adopted in the feature extraction algorithm, and the accuracy is further improved.

The invention discloses an optical fiber fault diagnosis method and system based on an SMC-BiLSTM network model, and the method comprises the following steps: measuring an optical fiber through an optical time domain reflectometer, and obtaining original optical time domain reflectometer data corresponding to different fault types; preprocessing the original optical time domain reflectometer data to obtain preprocessed optical time domain reflectometer data; the preprocessed optical time domain reflectometer data is input into an SMC-BiLSTM network model for training, and a trained SMC-BiLSTM network model is obtained; using the trained SMC-BiLSTM network model to diagnose the optical time domain reflectometer data to be identified, and obtaining the type of the optical fiber fault and the diagnosis result; according to the method, the optical time domain reflectometer data is acquired and preprocessed, and training and identification are performed based on the SMC-BiLSTM network model, so that intelligent diagnosis of optical fiber faults is realized.

The invention discloses a track zero calibration method of an optical time domain reflectometer and a related product, and the method comprises the steps that the optical time domain reflectometer emits a short pulse signal which sequentially passes through a reference optical fiber and an optical fiber to be measured, an original track curve corresponding to the short pulse signal is obtained, the reference optical fiber is arranged in the optical time domain reflectometer, and the reference optical fiber is arranged in the optical time domain reflectometer; the length of the reference optical fiber is greater than the spatial resolution of short pulse signal scanning; based on the original trajectory curve, determining reflected light power corresponding to the reference optical fiber; obtaining a first translation amount of the original trajectory curve based on the reflected light power corresponding to the reference optical fiber; and translating the original trajectory curve based on the first translation amount, completing calibration of a zero point, and obtaining an absolute loss trajectory curve corresponding to the to-be-measured optical fiber. Therefore, after zero calibration, the longitudinal axis value of the absolute loss trajectory curve can directly correspond to the absolute loss of each position of the optical fiber to be measured, and the trajectory curves of the same optical fiber at different moments can be conveniently compared, so that the readability of the trajectory curve is improved.

A method and system of measuring the PMD of an optical fiber under test (FUT). A polarization-sensitive optical time domain reflectometer (POTDR) is used to inject into the FUT and from a proximal end thereof, a test signal comprising a series of repeated light pulses and detecting a corresponding polarization-analyzed return light signal coming back from the optical fiber and representing back-reflected light from a light reflector connected to a distal end of the FUT. The plurality of polarization-sensitive acquisitions defines at least one pair of acquisitions performed with mutually different but closely-spaced wavelengths and substantially the same state of polarization (SOP). The process may be repeated for a plurality of pairs of acquisitions performed with at least one of a plurality of mutually-different center wavelengths and a plurality of mutually-different SOPs, and a value of the PMD for the FUT is calculated therefrom.

The application discloses a kind of distributed optical fiber monitoring sensing optical cable damage location method, it is related to distributed optical fiber monitoring technical field.The method includes: using OTDR optical time domain reflectometer to carry out preliminary measurement to sensing optical cable, it is judged whether optical cable exists damage and the preliminary measurement distance of damage point when existing damage;According to distance threshold value, it is judged whether bare optical fiber is fused, and OTDR secondary measurement is carried out, according to the measurement result record optical fading and the secondary measurement distance of each damage point;According to the optical fading, damage point is divided into two categories of " serious attenuation or broken fiber damage " and " moderate and below attenuation damage ", and the position of final damage point is positioned specifically.The application can be monitored by combined use of existing equipment of distributed optical fiber monitoring project itself, without separately purchasing other equipment.And, the optical cable damage location precision of the application can reach one meter, the positioning cost is low, the effect is good, and it is also applicable to the damage location of other communication optical cable.

A kind of weak reflection grating array reflectivity measurement method, using optical time domain reflectometer OTDR, including direct current light source, modulator, erbium-doped fiber amplifier, circulator, photoelectric detector, data acquisition card, data analysis processing module and display module;1) weak reflection grating array is accessed to above-mentioned measurement system, the weak reflection grating array to be measured is accessed to the second port of circulator;2) the output port of laser is connected with the input port of modulator;Laser output direct current light signal is modulated into probe light pulse by modulator, is amplified after being amplified by erbium-doped fiber amplifier, forms probe signal by entering the weak reflection grating array to be measured through circulator;3) the input port of photoelectric detector is connected with the third port of circulator;The input port of data acquisition card is connected with the output port of photoelectric detector;It is sent to data acquisition card by photoelectric detector output port;4) the output port of data acquisition card is connected with data analysis processing module.

The application discloses a vibration frequency estimation method based on amplitude difference step length, which comprises the following steps: laying sensing optical fibers on long-distance large infrastructure, and collecting RBS amplitudes of different vibration sampling points on the sensing optical fibers of the infrastructure to be measured under different detection pulses by using a phase-sensitive optical time domain reflectometer; effectively utilizing the difference step length corresponding to the maximum value point and the minimum value point of the maximum signal-to-noise ratio of the differential accumulated amplitude at the vibration sampling point to estimate the vibration frequency of the infrastructure to be measured; and comparing the vibration frequency of the infrastructure to be measured in the current state with the vibration frequency in the stable state to determine whether the structure of the infrastructure to be measured is healthy and safe. The application fully utilizes the strong dependence of the differential step length on the vibration frequency in the traditional amplitude differential accumulation algorithm, realizes accurate estimation of the vibration frequency, and utilizes the dynamic frequency to determine the health condition of the infrastructure to be measured, so that the destructive condition of the infrastructure to be measured is avoided, and the application has the advantages of simple structure, easy implementation and reliability.

The embodiment of the invention provides an optical fiber fault positioning method, system and device, a readable storage medium and a product. The method comprises the following steps: acquiring optical time domain reflectometer OTDR data of a target optical fiber link; identifying a fault reflection peak in the OTDR data, and calculating the linear distance between the optical line terminal and the breakpoint according to the propagation speed of the light in the optical fiber and the time difference between the light in the OTDR data and the fault reflection peak; matching the linear distance with a distance interval of each optical cable sub-segment in a pre-constructed bidirectional topological graph of the optical fiber network, and determining a target optical cable sub-segment where the breakpoint is located; acquiring a starting point coordinate, an end point coordinate and a length of the target optical cable sub-segment; and based on a coordinate interpolation algorithm, according to the starting point coordinate, the end point coordinate, the length and the linear distance of the target optical cable sub-segment, calculating the physical position of the breakpoint. According to the embodiment of the invention, automatic positioning of the optical fiber fault can be realized, the timeliness of fault discovery is improved, and manual intervention and field operation time are reduced.

The invention belongs to the technical field of optical fiber sensing, and provides a rapid demodulation device and method for correlation coding phi-OTDR, and the device comprises a laser, a coupler, a phase modulator, an acousto-optic modulator, an erbium-doped optical fiber amplifier, a circulator, a sensing optical fiber, a photoelectric detector, a low-pass filter, a rapid cross-correlation calculation module, a data collection card, and an upper computer. To-be-measured vibration acts on the sensing optical fiber, and after backward Rayleigh scattering signals are subjected to coded modulation and rapid cross-correlation decoding, vibration positioning and restoration are achieved through the system. The device and the method are applied to an optical fiber sensing technology, compared with a traditional phi-OTDR demodulation technology, the problems of high decoding delay and poor real-time performance are essentially solved, hardware acceleration decoding and preposed frequency shift are combined, and the device and the method have the advantages of low sampling rate acquisition, small data processing amount, high processing speed, high signal-to-noise ratio and the like. The method can be widely applied to the field of distributed vibration sensing and real-time monitoring.

The invention relates to an urban underground pipeline external force damage and road collapse supervision method and device, and belongs to the technical field of pipeline external force damage and road collapse supervision, and the method comprises the steps: an improved high-sensitivity phase-sensitive optical time domain reflectometer monitoring system senses a vibration signal, and processes and converts the vibration signal into a time-frequency spectrogram; inputting the time-frequency spectrogram into a pre-trained abnormal vibration signal classification identification and risk determination model to obtain a diagnosis result, and outputting the diagnosis result in a structured format; the diagnosis result, the occurrence time and the geographic position are uploaded to an intelligent management and control platform in real time, the intelligent management and control platform dynamically labels a GIS map according to the event type and the risk level, and a structured electronic maintenance work order is generated; and the intelligent management and control platform monitors the maintenance progress in real time and ensures a work order closed loop. The system can effectively sense, diagnose and warn underground pipeline external force damage and road collapse in a low-cost, high-safety and easy-to-operate manner.

The application relates to the technical field of data processing, and discloses a gateway service comprehensive management method and system based on FTTR demand. The method comprises the following steps: obtaining a room-level FTTR topology mapping table through topology scanning of an optical time domain reflectometer test signal, extracting features of service traffic of each room based on deep packet detection to obtain a room function identification label library, compensating attenuation of corresponding room optical ports by using an optical power meter to obtain an FTTR link quality evaluation matrix, performing bandwidth allocation by using a reinforcement learning algorithm to obtain a room-level QoS strategy configuration set, and obtaining an FTTR gateway service comprehensive management scheme based on MQTT protocol building data interaction. The application improves the intelligent level and resource allocation efficiency of room-level management of the FTTR network. The application improves the real-time performance of optical fiber link quality monitoring and the collaboration of building network management.

According to examples, systems and methods for communicating during bidirectional testing of a fiber optic link under test (LUT) are provided. This may include initiating a bidirectional measurement of the LUT, including initiating a first acquisition by a first optical time domain reflectometer (OTDR), receiving a request, prior to completion of the bidirectional measurement of the LUT, to send a multimedia message over the LUT during the bidirectional measurement of the LUT, and receiving information related to the multimedia message to be sent. In addition, this may include preparing the multimedia message to be sent over the LUT, determining a time slot during the bidirectional measurement of the LUT to send the multimedia message, and sending the multimedia message during the time slot over the LUT to a second OTDR.

The invention discloses a wireless monitoring system and method for intelligent multi-scene application, and belongs to the field of optical time domain reflectometers and the Internet of Things. According to the invention, OTDR detection and Internet of Things communication module transmission are adopted, so that remote, online and automatic monitoring of a line is realized. By monitoring the length change of the optical fiber in real time, faults of a conveying medium in various scenes can be found and an alarm can be given in time; on the basis of OTDR and Internet of Things technologies, idle optical fibers in multi-scene accompanying optical fibers can be tested in real time and intelligently analyzed, and once a fracture event is found, a client gives an alarm to inform maintenance personnel immediately and timely. Faults can be effectively reduced and prevented, the fault position is accurately positioned, the fault time is shortened, and the workload of maintenance personnel is reduced.

The invention discloses an optical time domain reflectometer special for a hollow-core optical cable, relates to the technical field of optical communication detection, and aims to solve the problems that an existing optical time domain reflectometer cannot adapt to detection of the hollow-core optical cable, is weak in low backscattering signal capturing capability, poor in operation and maintenance adaptability and the like. The reflectometer comprises a detection module, a light path module, a signal processing module, a fault identification and positioning module, a data interaction module and a power supply module. The detection module is optimally designed based on a photon counting detection principle, the optical path module realizes S + C + L ultra-wideband full coverage and adapts to common wavebands of the air-core optical cable, the signal processing module is internally provided with a special algorithm to improve the detection performance, equipment is convenient to receive after the modules are integrated and optimized, and accurate identification and positioning of various faults of the air-core optical cable can be realized. And data storage, export and remote transmission are supported. According to the invention, on-site mobile operation and maintenance requirements of the hollow-core optical cable are met, the detection efficiency and precision are improved, the industrial operation and maintenance cost is reduced, and technical support is provided for large-scale application of the hollow-core optical cable.

The invention discloses a few-mode optical fiber multi-damage parameter single-end synchronous measurement method and a few-mode optical time domain reflectometer thereof, and belongs to the technical field of optical fiber characteristic measurement. The method comprises the following steps: injecting an optical pulse into a few-mode optical fiber to be detected, and obtaining back Rayleigh scattering signals in multiple modes; carrying out wavelet transform denoising on the obtained backward Rayleigh scattering signal; processing the curve of the denoised back Rayleigh scattering signal by adopting a splicing algorithm so as to eliminate a front-end saturation blind area; differential mode group time delay is measured based on a Fresnel reflection peak single end, the feature position of the Fresnel reflection peak at the tail end of each mode curve is positioned, and the differential mode group time delay is calculated according to the position difference; and synchronously calculating a mode coupling coefficient and mode correlation loss based on the processed curve data. According to the invention, the measurement accuracy of the differential mode group delay is improved.

The application discloses a kind of intelligent substation secondary circuit fault arc online monitoring method and device, pulse optical signal is sent to the redundant optical fiber in the substation secondary circuit optical cable by optical time domain reflectometer, and Rayleigh backscattering signal is collected;Wavelet packet transform is carried out on scattering signal, the energy characteristics and entropy characteristics of each frequency band are calculated, and multidimensional feature vector is obtained;Non-dominated solution set is filtered by applying Pareto Front Optimization algorithm, and the Pareto optimal solution set of arc characteristics is obtained;The directed graph model of optical fiber sensing network is constructed, the arc candidate position is determined by applying directed minimum cut algorithm, and positioning is carried out by tree filling algorithm;Feature and position information are constructed into time sequence feature matrix, input into the CNN-LSTM hybrid network of Bayes online resource allocation optimization for classification identification;Locking decision strategy is generated based on fault diagnosis result, encapsulated as MMS message and sent to station control layer, and protection linkage is realized.

The invention discloses an external gating optical time domain reflectometer measurement method and device, and relates to the technical field of optical time domain reflectometers. The method comprises the steps that according to the Nth target segment and the N-1 photon count, the target optical power of a backward scattering light signal of the Nth target segment is determined, and N is a natural number and is larger than or equal to 2; enabling the generated periodic pulse laser signal to enter a to-be-measured optical fiber, so as to generate a backward scattering light signal in the to-be-measured optical fiber; under the condition that the generated Nth gating signal is conducted, outputting an Nth target section backward scattering light signal with target optical power of the backward scattering light signal; converting the Nth target section back scattering light signal into an Nth electric pulse signal; determining the Nth photon count according to the Nth electric pulse signal; traversing all target segments until all photon counts are determined; and determining a measurement result of the to-be-measured optical fiber according to all photon counts.

This invention discloses a method and system for event detection using an optical time-domain reflectometry (OTDR). The method includes the following steps: S1: Measuring the optical fiber using an OTD to obtain an OTD test curve; S2: Denoising the test curve data to obtain denoised test curve data; S3: Performing discrete wavelet transform and a constant false alarm rate (CFAR) algorithm based on the transform exponent to obtain wavelet coefficient reflection event points and wavelet coefficient non-reflection event points; S4: Merging the wavelet coefficient reflection event points and wavelet coefficient non-reflection event points and sorting them according to their positions; S5: Mapping the sorted wavelet coefficient reflection event points and wavelet coefficient non-reflection event points onto the test curve to obtain the true positions of the reflection event points and non-reflection event points, thus completing the OTD event detection. This invention can quickly and accurately locate targets, including nearby multiple targets and weak non-reflection events.

The invention provides a signal processing method based on a Brillouin optical time domain reflectometer system, which comprises the following steps: filtering an input signal to obtain an output signal, comparing an expected signal with the output signal to obtain an error signal, iteratively updating a weight coefficient of an adaptive filter, and repeatedly executing filtering operation by using the iteratively updated weight coefficient. Enabling an error signal to approach 0; and performing square operation on the filtered and denoised signal to obtain a square filtered and denoised signal, and performing envelope demodulation processing on the square filtered and denoised signal to obtain a root-mean-square envelope demodulation signal to determine a mutational sensing optical fiber signal. And according to the suddenly changed sensing optical fiber signal, determining a suddenly changed sensing optical fiber detection point. According to the method, the carried sensing information can be effectively extracted from a Brillouin optical time domain reflectometer signal containing a large amount of nonlinear noise, and demodulation and extraction of event points by a Brillouin optical time domain reflectometer system under a low signal-to-noise ratio are realized.