65 results about "Time-domain reflectometry" patented technology

The invention discloses a DNAPLs pollutant diffusion migration path depicting method and system, and relates to the technical field of pollution monitoring, and the method comprises the steps: obtaining the soil conductivity of a target region through an improved TDR probe, obtaining the time sequence characteristics and spatial characteristics of a soil conductivity data set, obtaining the fusion spatial-temporal characteristics, calculating the spatial-temporal similarity of historical migration paths, and obtaining the DNAPLs pollutant diffusion migration path depicting result. Screening prior knowledge; constructing a space-time prediction model by using a graph neural network and priori knowledge, extracting deep space-time features from a space adjacent graph and a time-dependent heterogeneous graph corresponding to the target region, and obtaining a conductivity prediction value of a future time step; the diffusion direction of the pollutants is deduced by combining the relation between the resistivity and the DNAPLs concentration, migration frontal surface diagrams at different time points are drawn, and dynamic path visualization is achieved. According to the method, the improved TDR (time domain reflectometry) technology and the deep learning model are combined, so that high-precision monitoring and prediction of the dynamic migration process of the pollutants are realized.

The proposed full-coherent optical time domain reflectometry (FC-OTDR) solution extracts full optical phase and state of the polarization (SOP) information for fiber intrusion detection by constructing a continuous reflected SOP from each point of the fiber length. Intrusion location is then extracted from the resulting SOP change patterns.

The invention relates to the technical field of numerically-controlled machine tool monitoring, in particular to a numerically-controlled machine tool monitoring method and system, terminal equipment and a storage medium, and the numerically-controlled machine tool monitoring method comprises the following steps: based on key parts of a numerically-controlled machine tool, monitoring tiny wear or deformation by adopting a time domain reflection method and a frequency domain reflection method; and the collected ultrasonic signals are analyzed in combination with a convolutional neural network, phase changes and abnormal features in the signals are identified, data fusion processing is carried out, and wear identification indexes are generated. According to the method, the advanced monitoring and analysis technology is adopted, comprehensive optimization of the performance of the numerical control machine tool is achieved, the time domain reflection method and the frequency domain reflection method are combined with convolutional neural network analysis, the detection precision of tiny abrasion or deformation is improved, dynamic optimization is achieved on clamping force adjustment through fuzzy logic control, the method adapts to different machining conditions, and the machining precision of the numerical control machine tool is improved. Workpiece damage is reduced, the machining quality is improved, and the machining precision is improved through deep diagnosis and dynamic compensation strategies of multi-axis synchronous errors.

The invention relates to the technical field of electric power, in particular to a cable nondestructive testing method which comprises the following steps: acquiring corresponding calibration parameters from a database according to the model of a to-be-tested cable, and calculating the total length and fault position of the to-be-tested cable at the near end of the to-be-tested cable by adopting a time domain reflection method; at the tail end of the cable to be detected, at the tail end, at least two core wires are short-circuited, a four-wire detection method is adopted to measure the direct-current resistance of a core wire loop at the near end, and standard temperature correction is conducted on the direct-current resistance of a single core wire; the resistivity to be measured is calculated by using the total length of the cable to be measured, the actual cross sectional area of the core wire and the direct current resistance of the single core wire at the standard temperature, and whether the actual core wire material of the cable to be measured is qualified is analyzed according to the resistivity to be measured and a resistivity threshold value set based on the calibrated core wire material. And early warning is carried out based on a core wire material analysis result and a fault position. According to the method, the cable length, the fault position and the core wire material qualification can be quickly, nondestructively and accurately detected on site.

The application discloses an optical time domain reflectometry (OTDR) method, system and OTDR equipment for avoiding event blind area, and relates to the technical field of OTDR. The OTDR method adds a second detector to the ground end of a first detector, and detects the optical signal emitted by a second light source by using the second detector. Then, when measuring the OTDR curve of a to-be-measured optical fiber, the second driver is controlled to drive the second light source to emit a compensation optical signal within a pre-determined saturation time interval, so that the photocurrent detected by the second detector offsets and compensates the photocurrent detected by the first detector, and the current input to the amplification circuit is lower than the saturation threshold, thereby eliminating the event blind area caused by saturation, enabling the blind area event to be detected, and without adding a selection switch, thereby avoiding introducing additional noise, improving the optical fiber OTDR test accuracy and having better noise performance.

The invention specifically relates to a cable defect identification and positioning method based on a broadband impedance spectrum, and belongs to the technical field of power distribution network equipment fault detection. According to the method, the advantages of the frequency domain reflection method and the reflection method are comprehensively considered, whether the parameters of the frequency domain reflection method and the time domain reflection method need to be corrected or not is judged by using the positioning deviation degree, the positioning deviation degree, the fluctuation width and the combined positioning ratio are used as indexes in the correction process, the respective defects of the frequency domain reflection method and the time domain reflection method are eliminated, and the correction accuracy is improved. The advantages are fused, and the corrected parameters are adopted for positioning, so that the accuracy of cable defect positioning and identification is greatly improved.

Systems, methods, and apparatus, including computer programs encoded on computer-readable media, for downhole fault detection in a well system are disclosed. A spread spectrum time domain reflectometry (SSTDR) apparatus of the well system may transmit an SSTDR signal downhole via a well electrical cable of the well system and receive a reflected SSTDR signal. The SSTDR apparatus may determine whether a downhole fault exists in the well electrical cable or in a well device based on a signal analysis of the reflected SSTDR signal and the transmitted SSTDR signal. The SSTDR apparatus may also use historical SSTDR data and a machine learning algorithm for downhole fault detection and analysis. When a downhole fault is detected, the SSTDR apparatus also may determine a type of the downhole fault and a location of the downhole fault, such as the depth downhole of the downhole fault.

The invention belongs to the field of ocean geophysical exploration, and particularly provides a device and a method for monitoring migration of CO2 in sediment based on a time domain reflectometry, the monitoring device comprises a reaction kettle, a vacuumizing and saturation system, a supercritical carbon dioxide preparation and injection system, a temperature control system, a dielectric constant test control system and a data acquisition and processing system; the dielectric constant test control system comprises a time domain reflection tester and a time domain reflection sensor assembly, wherein the time domain reflection sensor assembly comprises a plurality of axial time domain reflection sensors inserted from the bottom of the reaction kettle and a plurality of radial time domain reflection sensors inserted from the side surface of the reaction kettle. According to the device and the method, anisotropic dynamic monitoring of the continuous migration process of supercritical CO2 in the ocean sediment can be realized, and combined characterization of CO2 saturation and CO2 plume front migration dynamics in the sediment sample in the CO2 migration process can be realized, so that accurate evaluation of the storage efficiency and leakage risk of CO2 in the ocean sediment is realized, the monitoring effect is good, and the operation is simple.

The invention provides an electronic wire harness anti-interference optimization method and system, and the method comprises the steps: S2, blocking a DC component and low-frequency interference through employing a band elimination filter according to the initial spectrum distribution, and extracting a core frequency band of high-frequency signal transmission from a filtered signal; s4, acquiring demand data of voltage grade separation from the signal output, designing an electrical isolation layer through a multi-layer shielding structure, and determining isolation boundaries among different voltage grades; s5, according to the isolation boundary, a space optimization algorithm is adopted to adjust wire harness arrangement in the compact layout, and structural parameters considering isolation and coupling balance are obtained; and S8, according to the final scheme, a time domain reflection method is adopted to detect the distortion rate in signal transmission, the actual effect of improving the anti-interference capability is judged from the detection result, and optimized operation parameters are obtained. The anti-interference capability and the signal transmission quality of the electronic wire harness in a complex electromagnetic environment are effectively improved.

The invention discloses an event identification method, device and equipment for COTDR data and a storage medium, and the method comprises the steps: obtaining coherent optical time domain reflectometry (COTDR) curve data, carrying out the smoothing of the COTDR curve data according to a preset moving average algorithm, and obtaining the smoothed COTDR curve data; dividing the smoothed COTDR curve data into an effective COTDR curve and noise, and obtaining abnormal point information of the effective COTDR curve; and analyzing the abnormal point information to obtain event point information corresponding to different events in different categories, so that the event information can be automatically obtained in real time, the personnel judgment difficulty is reduced, the operation and maintenance automation capability of the ocean communication system is improved, the arithmetic logic is simple, the code complexity is reduced, and the operation efficiency is improved. Unification of a COTDR monitoring system and a communication equipment management system is realized, and the event identification speed and efficiency of the COTDR data are improved.

This improves the degradation of the cross-correlation coefficient caused by the error between the set frequency and the actual frequency of the light source, and makes it possible to improve the degradation of the measurement accuracy of strain and temperature. [Solution] The light source unit has a frequency-stabilized wavelength-tunable laser that generates continuous light, and a first optical coupler splits the continuous light generated by the light source unit into two, sending one to a second optical coupler and the other to an optical frequency measurement unit. The optical frequency measurement unit measures the frequency of the continuous light generated by the light source unit, and the second optical coupler further splits the continuous light split by the first optical coupler into two, sending one as probe light to the optical pulse generation unit and the other as local light to a detection unit. The detection unit measures the frequency change Δf by means of coherent time domain reflectometry and a means for heterodyne detection of the Rayleigh scattered light and the local light resulting from Rayleigh scattering of pulsed light in the fiber under test. max and means for acquiring the

The invention belongs to the technical field of optical fiber sensing, and relates to an optical time domain reflection monitoring method and device based on forward and reverse signal joint optimization, and the method comprises the steps: obtaining reverse and forward OTDR observation signals of a to-be-measured optical fiber; constructing a reverse OTDR linear signal reconstruction item based on a product of the orthogonal transformation matrix and a to-be-solved first sparse coefficient vector; constructing a forward OTDR linear signal reconstruction item based on the product of the orthogonal transformation matrix and a to-be-solved second sparse coefficient vector; constructing a data fidelity item based on the OTDR observation signal and the linear signal reconstruction item; constructing a joint sparse regular term based on the structural sparsity of the first sparse coefficient vector and the second sparse coefficient vector to be solved; and constructing a spatial constraint regular term based on the continuous smoothness of the reconstructed OTDR linear signal in the space, thereby constructing a joint optimization function and solving the joint optimization function to obtain a first sparse coefficient vector and a second sparse coefficient vector, and further reconstructing the OTDR linear signal to detect the optical fiber to be detected.

The invention discloses a method and a system for automatically analyzing OTDR (Optical Time Domain Reflectometry) test curves of a hollow-core optical fiber. The method comprises the following steps of: acquiring one OTDR test curve from each of two ends of the hollow-core optical fiber; respectively carrying out centralization processing on the two OTDR test curves, aligning the two OTDR test curves based on the position of the hollow-core optical fiber, calculating a difference value of backscattering power of the two OTDR test curves, and then calculating an average value to obtain a correction curve; performing filtering and noise reduction processing on the corrected curve to obtain a curve after noise reduction; extracting event information from the denoised curve by adopting a multi-scale analysis and dynamic threshold fusion algorithm; and exporting an event detection result according to the event information. According to the invention, automatic processing and analysis of the hollow-core optical fiber OTDR curve are realized while bump interference is avoided.

A computer-implemented method for performing an enhanced resolution time domain reflectometry is provided. Aspects include obtaining a plurality of waveforms by transmitting a first pulse on a transmission line, transmitting a second pulse on the transmission line, where the second pulse is transmitted after the first pulse by a delay, and capturing and measuring reflections of the transmitted pulses, where the delays corresponding to each of the plurality of waveforms are different. Aspects also include identifying a discontinuity of the transmission line based at least in part on the plurality of waveforms. Based on determining that the transmission line includes a discontinuity, the aspects include calculating a third derivative curve for each of the plurality of waveforms, and calculating a length of the discontinuity of the transmission line based on the third derivative curves. Aspects also include creating a notification indicative of the location and length of the discontinuity of the transmission line.

The invention relates to the technical field of cable fault positioning, in particular to a cable fault accurate positioning method and system for cable health monitoring, and the method comprises the steps: obtaining a collection reflection section and an experiment reflection section; obtaining the matching degree of the experimental reflection section; other parameters except the noise intensity in the experiment parameter group are constant, and the noise intensity is quantitatively analyzed to obtain the comprehensive matching degree of the collection reflection section and the experiment reflection section; screening the parameter groups to obtain a plurality of matching parameter groups and a reflection initial search range; comprehensively analyzing the probability that the correlation degree of the reflected pulse signal and the matching parameter group reflects each moment as the starting moment, and selecting the starting moment of the reflected pulse signal; and obtaining the distance of the fault point by using the starting time of the reflected pulse signal. The invention aims to solve the interference of noise on the starting moment of the reflected pulse signal and improve the accuracy of the time domain reflection method.

Methods and apparatus for characterizing an optical fiber link by optical time domain reflectometry are disclosed. In order to solve the problem of trade-off among signal-to-noise ratio, duration and resolution of optical time domain reflectometry, the embodiment of the invention uses a coded return-to-zero optical pulse sequence. Each return-to-zero light pulse in the coded sequence includes a guard interval to mitigate the effects of pulse shape distortion. In some embodiments, the return-to-zero light pulse sequence is encoded with a complementary Gaulay correlation code. Some embodiments provide methods for encoding and decoding a sequence in a return-to-zero pulse sequence. Some embodiments provide an optical time domain reflectometry apparatus including a light source unit, an optical coupler, a light sensor, and a processing device.

Leakage detection systems and methods of monitoring leakage using probes of fiber optic and / or Time Domain Reflectometry (TDR) cables that provide at least one of an electric and electromagnetic signal upon coming in contact with a liquid from the pool. An interrogator may be multiplexed with several of the cables and generate interrogation signals whose reflection determines an exact position along the cable of leakage contact. The cables may be run under a floor and / or wall of a spent fuel pool or other liquid volume in a nuclear power plant. Leakage even of deionized water near room temperature may be detectable. The cables may be a single serpentine cable or several straight cables wrapping around the volume. The cables may be small, such as 10 millimeters or less in diameter. Cables may be run behind liners at any pitch or interval, potentially between supporting structures and the liner.

The invention provides a pulse width modulation optical time domain reflection detection device for discharge pressure waves in transformer oil. Based on an optical path of a heterodyne coherent optical time domain reflectometer, three time sequence pulses are adopted to modulate continuous optical signals to enter an optical fiber, backward Rayleigh scattering signals are generated, the optical fiber is placed in transformer oil to measure pressure waves generated by partial discharge, and the pressure waves are measured through the mathematical relationship between the pressure waves and the backward Rayleigh scattering signals. And through wavelet denoising, least square smoothing and Hilbert demodulation phase extraction, the measurement of the partial discharge pressure waves in the transformer is finally realized.

Embodiments of the present application disclose a folding screen auxiliary device, a manufacturing method thereof and related equipment. The device includes a balanced transmission line, which includes a first conductive layer, a dielectric layer and a second conductive layer stacked in sequence; the first end of the first conductive layer is connected with a time domain reflectometry (TDR) module, and the first end of the second conductive layer is grounded; the first conductive layer is used to receive a first pulse signal transmitted by the TDR module; when the folding screen is bent, the thickness of the bending area of the dielectric layer is reduced from a first thickness to a second thickness; the first conductive layer is further used to form a corresponding first reflection signal based on the first pulse signal, and transmit the first reflection signal to the TDR module; the TDR module is used to determine the bending angle of the folding screen based on the first pulse signal and the first reflection signal. The embodiments of the present application can realize low-cost, lightweight and high-precision folding screen bending angle identification, and improve the user experience.

The invention discloses a coaxial fibrosis TDR sensor and a preparation method thereof, and a distributed monitoring system, and relates to the technical field of flexible distributed sensor design, the sensor is realized by adopting a flexible coaxial structure comprising a central conductor, a sensitive medium layer, an outer braided shielding layer and a protective layer which are sequentially arranged from inside to outside; the central conductor and the sensitive dielectric layer serve as signal transmission conductors and are used for bearing and transmitting excitation pulse signals; the sensitive dielectric layer adopts any one of a temperature, pressure and strain single sensitive dielectric layer or a temperature-strain and pressure-strain coupling sensitive dielectric layer, and is used for correspondingly responding to changes of external temperature, pressure and strain respectively, changing the dielectric constant and the geometric dimension of the sensitive dielectric layer, causing local impedance disturbance, and realizing the temperature, pressure and strain sensing. The TDR reflection signal generates time delay and amplitude change; and the outer braided shielding layer and the protective layer are respectively used for shielding external electromagnetic interference and protecting machinery and environment. According to the invention, distributed positioning and quantitative analysis of multiple physical quantities can be realized.

A distributed acoustic sensing (DAS) system that is configured to generate, at each scan period, at least two corresponding optical pulses such as a first pulse and a second pulse, where the pulses are of equivalent (similar or same) optical characteristics and cause a time-delay between those at least two pulses for example by directing each of the pulses through a different optical fiber of different fiber lengths, such as to form a time difference At between those at least two pulses. Each of the generated pulses may be directed through a sensing optical fiber of the DAS system, where one or more optical characteristics of (e.g., Rayleigh) backscattered light returned from the sensing optical fiber can be detected for determination of one or more updated properties of acoustic wave(s) influencing the sensing optical fiber for detection of acoustical influences such as mechanical strains, acoustic vibrations etc.

The application belongs to the technical field of optical fiber sensing, and relates to an optical time domain reflection monitoring method and device based on joint optimization of forward and reverse signals. Reverse and forward OTDR observation signals of a to-be-detected optical fiber are acquired. A reverse OTDR linear signal reconstruction term is constructed based on the product of a orthogonal transformation matrix and a first sparse coefficient vector to be solved. A forward OTDR linear signal reconstruction term is constructed based on the product of the orthogonal transformation matrix and a second sparse coefficient vector to be solved. A data fidelity term is constructed based on the OTDR observation signals and the linear signal reconstruction terms. A joint sparse regularization term is constructed based on the structured sparsity of the first sparse coefficient vector and the second sparse coefficient vector to be solved. A spatial constraint regularization term is constructed based on the continuous smoothness of the reconstructed OTDR linear signal in space. Thus, a joint optimization function is constructed and solved to obtain the first sparse coefficient vector and the second sparse coefficient vector, and the OTDR linear signal is reconstructed to detect the to-be-detected optical fiber.

The present disclosure relates to techniques for visualizing multiple time domain reflectometry waveforms. Various embodiments include a TDR viewer for visualizing a large number of reflected TDR signals on a 3D display system. The TDR system captures waveforms of reflected TDR signals associated with signal propagation and delay. The TDR viewer displays waveforms of signals as they propagate through a transmission line. These waveforms can show changes in the reflected TDR signals due to transmission between various printed circuit board layers, through printed circuit board component connectors and vias, and across interconnects and socket pins. The 3D visualization of the reflected TDR signals can be rotated, zoomed in or out, and filtered to display a subset of signals in the 3D space. The 3D visualization enables a test engineer to more quickly identify TDR signals of interest, including signals with longer or shorter delay times relative to other TDR signals and signals exhibiting undesirable signal properties.

The present application relates to the technical field of optical fiber sensing, and particularly relates to a fusion type optical fiber disturbance detection system and method based on multi-modal scattering. The system comprises a light source module, an optical fiber sensing network, an optical signal demodulation module, a data processing unit and an adaptive disturbance recognition module. By simultaneously extracting characteristic information of Rayleigh scattering and Raman scattering, the detection sensitivity and accuracy of different types of disturbances can be improved. The system adopts an adaptive disturbance recognition algorithm, dynamically adjusts the fusion weight of Rayleigh scattering and Raman scattering by using information entropy calculation, so as to adapt to the disturbance detection requirements under different environmental conditions, improve the adaptability and reliability of the system, and effectively reduce the false alarm rate. In addition, the data processing unit combines the principle of optical time domain reflectometry (OTDR), calculates the time difference of the disturbance signal arriving at the demodulation module, and realizes high-precision disturbance positioning.

Leakage detection systems and methods of monitoring leakage using probes of fiber optic and / or Time Domain Reflectometry (TDR) cables that provide at least one of an electric and electromagnetic signal upon coming in contact with a liquid from the pool. An interrogator may be multiplexed with several of the cables and generate interrogation signals whose reflection determines an exact position along the cable of leakage contact. The cables may be run under a floor and / or wall of a spent fuel pool or other liquid volume in a nuclear power plant. Leakage even of deionized water near room temperature may be detectable. The cables may be a single serpentine cable or several straight cables wrapping around the volume. The cables may be small, such as 10 millimeters or less in diameter. Cables may be run behind liners at any pitch or interval, potentially between supporting structures and the liner.

A time domain reflectometry (TDR) controlled-impedance testing system includes one or more ultra-low impedance testing channels (e.g., having a characteristic impedance of less than 10 ohms, or less than 5 ohms, or less than 2 ohms) to couple a test signal to a test target ("device under test"). In one example, the TDR testing system includes one or more printed circuit boards (PCBs) on which at least a portion of the testing channel is implemented. The PCB includes an ultra-wide impedance-controlled trace and one or more return conductors constituting at least a portion of an ultra-low impedance PCB RF transmission line having a characteristic impedance of less than 10 ohms (or less than 5 ohms, or less than 2 ohms).

A grounding cable high-frequency signal detection method, system, device and medium adopt compressed sensing (CS) technology, through sparse representation and compressed sampling of cable reflection signal, the amount of sampling data is significantly reduced, and through the sparse signal reconstruction algorithm, the efficient reconstruction of the cable reflection signal is realized, the problems of slow signal processing speed, poor anti-interference ability and low detection precision in the prior art are solved; the system is composed of a signal acquisition module, a compressed sampling module, a signal reconstruction module and a fault detection and positioning module, and can realize accurate judgment of the type and position of the cable fault in a complex environment, and is especially suitable for online monitoring of long-distance cables; the device and medium detect the grounding cable high-frequency signal based on the above detection method and system, compared with the existing time domain reflection method (TDR), the application has higher detection sensitivity, anti-interference ability and processing speed, and can complete cable fault diagnosis and attenuation compensation without reference data, and provides a fast and reliable solution for cable state monitoring.

The invention relates to a method and ethernet physical layer device for detecting, classifying and localizing cable faults of an ethernet physical cable, particularly an automotive ethernet PHY, using a time domain reflectometry algorithm, using a hybrid mode for selectively subtracting sent signals from received signals for fault detection and classification and considering send and received signals during fault localization.

This invention discloses an adaptive filtering method for phase-sensitive optical time-domain reflectometry (OTDR) signals. The method evaluates the quality of non-local mean filtering results by calculating correlation coefficients, and the filtering quality can be used to optimize the filtering parameters of the image filtering method. These parameters are first verified using a hypothetical standard signal and then applied to denoising a real signal from a phase-sensitive OTD instrument. Comparison of the correlation-optimized filtering parameters with those optimized using traditional peak signal-to-noise ratio (PSNR) and structural similarity methods shows that, except for slight differences in the neighborhood window size, the optimized filtering parameters are almost identical. This method is also applicable to image filtering of other two-dimensional periodic signals.

The invention relates to a high-positioning-precision power cable fault detection method based on a time-frequency domain reflection method, and aims to solve the technical problems of insufficient positioning precision and weak anti-interference capability of a traditional fault detection method. The method comprises the following steps: firstly, enabling a power cable to be equivalent to a uniform transmission line distribution parameter model, and generating a Gaussian envelope linear frequency modulation incident signal meeting a detection requirement by utilizing a time-frequency domain reflection method and fusing the technical advantages of a time domain reflection method and a frequency domain reflection method, and injecting the Gaussian envelope linear frequency modulation incident signal into a target cable; the method comprises the following steps: performing smooth pseudo Wigner-Ville distribution time-frequency transformation on a cable reflection signal to obtain a time-frequency domain image; aiming at the problem of shape distortion caused by elliptic features presented by GELC signals after SPWVD transformation and noise interference, a Hough transformation ellipse detection algorithm is adopted, ellipse feature parameters are accumulated and counted in a parameter space through preprocessing steps of image graying, threshold segmentation, contour extraction and the like, an ellipse center corresponding to a time-frequency correlation peak is accurately positioned, and a time-frequency correlation curve is obtained. And determining the position of a cable fault point. The method effectively overcomes the limitation of a single-domain reflection method and the influence of noise interference, remarkably improves the precision and reliability of power cable fault positioning, and is suitable for fault detection scenes of open circuit, short circuit, impedance mismatching and the like of various power cables.