17 results about "Time-domain reflectometer" patented technology

A system and method for distributed temperature and strain sensing using Chirp-Pulse Coherent Optical Time-Domain Reflectometry (CP-COTDR) utilizes optical flow processing. The method involves constructing a two-dimensional (2-D) waterfall data array from collected CP-COTDR frames. Optical flow processing is applied directly to the 2-D data to estimate the local shift of features caused by external perturbations. The optical flow is preferably calculated using a weighted least squares method with an adaptive analysis window based on the local flatness of signal derivatives. This approach provides versatile and high spatial resolution, reduces accumulative errors, and enables efficient data processing compared to conventional cross-correlation techniques.

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.

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.

This disclosure relates to the optical fiber sensing technology, and more particularly to an optical time-domain reflectometer and an interference fading rejection method, and includes a laser device, a frequency division multiplex modulator, a circulator and a signal processing device, wherein the frequency division multiplex modulator includes a first modulator, a second modulator, a first attenuator and a second attenuator, the laser device is used to acquire a coherent light source, the coherent light source passes sequentially through the first modulator and the first attenuator to acquire the first pulsed optical signal, the coherent light source passes sequentially through the first modulator and the second modulator to acquire the second pulsed optical signal, the coherent light source passes sequentially through the second attenuator and the second modulator to acquire the third pulsed optical signal, and the output of multiple pulsed optical signals can be realized by different combinations of the first modulator, the second modulator, the first attenuator and the second attenuator, saving hardware costs compared to existing technologies.

The application discloses a compact time domain reflectometer probe based on high-speed logic gates, which comprises a power filter module, an ultrafast edge pulse generation module, an impedance matching driving module and a signal separation and test port module, the power filter module supplies power for the ultrafast edge pulse generation module and the impedance matching driving module, the ultrafast edge pulse generation module is a relaxation oscillator, the relaxation oscillator outputs a square wave signal to the impedance matching driving module, the impedance matching driving module inputs the square wave signal after impedance matching to the signal separation and test port module, and the signal separation and test port module comprises a triangular resistance distribution network formed by three resistors. Compared with the existing simple TDR scheme or expensive professional equipment, the time domain reflectometer probe disclosed by the application has the advantages of high resolution, excellent impedance matching, compact structure, low cost and the like.

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.

Embodiments of the present application provide a detection method of a passive optical network, a storage medium, an electronic device and a computer program product. The method comprises: controlling an optical time domain reflectometer to detect a plurality of PON ports in the passive optical network (PON) using different wavelengths to obtain detection data of a plurality of reflection events; and determining a detection result of the PON according to the detection data of the plurality of reflection events and data of a reference reflection event stored in advance. According to the embodiments of the present application, all reflection events on the optical path do not need to be detected, but only the reflection events of the specified wavelength in the optical path of the PON port are detected, thereby improving the efficiency of the detection method of the PON network. In addition, the detection result of the PON can be determined by comparing the detection data of the plurality of reflection events with the data of the reference reflection event stored in advance, the fault condition can be analyzed, and the accuracy of the detection method of the PON network is improved. Therefore, the problem of low efficiency and accuracy of the detection method of the PON network can be solved.

This invention relates to a phase-sensitive optical time-domain reflectometer based on orthogonal frequency division multiplexing (OFDM) pulse coding. A continuous laser beam is split into a local path and a probe path via an optical coupler. The probe path, driven by a radio frequency signal, generates multiple frequency-orthogonal intensity-coded pulse sequences through an optical intensity modulator. These sequences are arranged sequentially in time, possessing the same symbol information but different chip sequences. The Rayleigh backscattered light generated by the pulse sequences entering the sensing fiber under test undergoes coherent interference with the local light in an optical bridge and polarization diversity module. The signal acquisition circuit utilizes an unmatched filter to achieve pulse compression and Rayleigh scattering signal separation, and synthesizes the results of the pulse coding sequences at each frequency to obtain the strain signal. Compared with existing technologies, this invention achieves pulse compression by designing an unmatched filter, improving the signal-to-noise ratio while maintaining spatial resolution. Furthermore, by synthesizing the results of orthogonal frequency pulse sequences, coherent fading is eliminated, achieving fading-free, high signal-to-noise ratio strain measurement.

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.

This utility model discloses a monitoring and early warning device for frost heave deformation in water conservancy engineering channels, relating to the field of monitoring and early warning technology. It includes a track and a platform. The platform is located on one side of the track, and an installation box is fixedly embedded in the middle of the platform. A time-domain reflectometer (TDRI) is inserted inside the installation box. A fixed column is fixedly embedded at one corner of the platform, and multiple marker rods are equidistantly inserted on the fixed column. Each marker rod includes a head rod, a color rod, and a fixed cone. The head rod has a cavity inside, and a rotating shaft is rotatably connected to the inner wall of the cavity. This utility model, a monitoring and early warning device for frost heave deformation in water conservancy engineering channels, by setting up a track, a sliding plate, and a platform, and cooperating with the installation box embedded in the platform, allows the TDRI to be fixedly installed at multiple interval monitoring points in the water conservancy engineering channel, forming a detection platform to quickly measure the current soil moisture content and other conditions to determine the frost heave risk level. The frost heave risk level can be determined by pressing the corresponding color-coded marker rod.

This invention belongs to the field of optical fiber testing and sensing technology, specifically relating to a method for identifying faults and disturbances in few-mode optical fibers using Raman-enhanced time-domain reflectometry (TDDR). The method includes: signal transmission based on pulse coding and mode-selective excitation; signal-to-noise ratio enhancement based on distributed Raman amplification; mode demultiplexing and mode field detection; coded demodulation and reconstruction using a multi-mode few-mode optical TDDR; multi-dimensional fault identification based on mode-dependent loss and coupling characteristics; and multi-mode differential and high-precision positioning based on digital signal processing. This invention targets high-capacity communication and distributed sensing systems using few-mode fibers. It solves the problem of detecting weak inter-mode scattering signals by coordinating pulse coding gain and distributed Raman optical gain. Subsequently, it utilizes the unique mode-dependent loss and inter-mode energy transfer characteristics of few-mode fibers for joint decision-making, providing highly sensitive, multi-dimensional optical fiber link health monitoring capabilities. This method has great potential and application prospects in the operation and maintenance of next-generation space-multiplexed optical networks.

There is provided a method for measuring the spectral transmission response of a DUT using a multi-wavelength Optical Time Domain Reflectometer (OTDR) which allows performing OTDR measurements across a spectral range of interest. The OTDR targets a single reflective OTDR event along the OTDR trace, e.g., a mirror, a non-angled polished (UPC) connector or any other reflective surface located at the remote end of the DUT, which reflectance peak in combination with a reference measurement allows to perform single-end measurements of the transmission response. The process is repeated at various wavelengths to obtain a spectral transmission response of the DUT.

Real equivalent time oscilloscope with time domain reflectometer. A test and measurement device includes one or more ports configured to connect to a device under test (DUT), a time domain reflectometer (TDR) source configured to receive a source control signal and generate an incident signal to be applied to the DUT, one or more analog-to-digital converters (ADCs) configured to receive a sampling clock and sample the incident signal from the TDR source and a time domain reflectometry (TDR) signal or a time domain transmission (TDT) signal from the DUT to generate an incident waveform and a TDR / TDT waveform, one or more processors configured to execute code to cause the one or more processors to control a clock synthesizer to generate the sampling clock and the source control signal and determine time positions of samples in the incident waveform and the TDR / TDT waveform using a period of the TDR source, a period of the sampling clock, and a number of samples, and a display configured to display the incident waveform and the TDR / TDT waveform.

A distributed acoustic sensing (DAS) system may include an optical fiber, and a phase-sensitive optical time domain reflectometer (φ-OTDR) coupled to the optical fiber and configured to collect DAS frequency domain spectral data therefrom in a plurality of spatial channels. The system may also include a processor cooperating with the φ-OTDR and configured to group spatial channels by respective frequency responses thereof, process DAS frequency domain spectral data for respective spatial channels within each group using a same polynomial filter, determine acoustic events associated with the optical channels based upon the processed DAS frequency domain spectral data, and generate an acoustic event report from the acoustic events.

This invention discloses a slope stress and flow field coupling monitoring device and method based on fiber optic sensing, belonging to the field of slope stability monitoring technology. The device comprises a base at the bottom of a housing, with a lifting assembly located below one end of the base. The housing is filled with experimental soil, with optical fibers embedded both inside and on the surface of the soil. A rainfall assembly is located above the housing, and several pore water pressure sensors are positioned above the base. The outputs of the pore water pressure sensors and the optical fibers are connected to the input of a Brillouin optical time domain reflectometer (OTDR). The output of the OOTDR is connected to the input of a main control module, which controls the lifting assembly, the rainfall assembly, and generates early warning signals. This invention solves the problems of missing multi-field coupling and discontinuous monitoring in existing technologies, improving the simulation realism of slope rainfall-induced instability processes.

1. Name of the product in this design: Multifunctional Optical Time Domain Reflectometer (MT-6610). 2. Purpose of this product design: It is used to detect fiber optic breaks, losses, attenuation, etc., as well as to detect the location of events such as fiber optic splices and bends, and to locate optical cables by vibration or macro-bends, so as to facilitate engineers to find and troubleshoot faults. 3. The key design features of this product are its perspective view. 4. The image or photograph that best illustrates the design's key points: a 3D model. 5. The right view is symmetrical to the left view, so the right view is omitted.