40 results about "Distributed acoustic sensing" patented technology

This application relates to a Rayleigh scattering noise suppression method and system for a distributed acoustic wave detection system. The method includes: performing optical phase sinusoidal modulation on a high-coherence continuous laser output from a narrow-linewidth laser in an FBG-based distributed acoustic detection system according to a set modulation scheme using an optical phase modulator; the set modulation scheme is Csin(2πf m t), C is the phase modulation amplitude, f m The phase modulation frequency and satisfying f m τ = k, where τ is the time difference between two adjacent reflected light pulses being detected, t is time, and k is an integer. A highly coherent continuous laser beam with sinusoidal phase modulation is passed through an unbalanced interferometer to generate dual light pulses. These dual light pulses are then injected into an FBG array for distributed acoustic wave detection. This achieves low-noise distributed acoustic wave detection and effectively improves the detection performance of FBG-based distributed acoustic wave detection.

The invention relates to a vehicle-type-based traffic flow monitoring DAS system and a signal processing method, and belongs to the technical field of intelligent traffic monitoring. A DAS system for monitoring traffic flow based on different vehicle types is characterized by comprising a sensing module based on a phase-sensitive optical time domain reflection technology and a self-adaptive signal processing module, according to the system, firstly, road vibration data are collected by using an optical fiber distributed acoustic sensing technology, vehicle vibration characteristics are selectively enhanced and background interference is suppressed in a key frequency band of 10-80 Hz through DAS-PCSE based on enhanced ultra-wavelet transform, and high-stability input characterization is generated; then, the preprocessed data are input into a lightweight DAS Trajectory Net, the network takes an encoder-decoder as a skeleton and introduces an adaptive feature enhancement module, and accurate recognition of a vehicle track is achieved; and finally, through a DAS Veple Classifier Net, a double-current signal processing module and lightweight convolution are utilized to efficiently fuse spatio-temporal information, and vehicle type discrimination is completed. According to the invention, the influence of low signal-to-noise ratio and complex background disturbance can be effectively overcome, and wide-area and all-weather vehicle-type-based traffic flow and vehicle speed monitoring can be realized with low calculation cost.

There is provided a method and system of frequency dithered distributed acoustic sensing (FD-DAS) using group data signal processing, where the continuous wave (CW) coherent laser's optical frequency or optical phase for the FD-DAS interrogator may be set in evenly or randomly distributed manner for different data groups but they are kept as constant or with negligibly variation within each data group. Such FD-DAS may be used to improve acoustic or vibration signal measurement reliability, to allow to use a low-cost single-frequency laser such as a DFB laser, and / or to suppress polarization fading effect.

A system for autonomously deploying geophysical cables in sand dunes includes a surface station positioned at the sand dunes, one or more subsurface burrowing robots including distributed acoustic sensing geophysical cables laying robot, and a geo-locating radio system (GLRS). The one or more subsurface burrowing robots digs in the sand dunes to a target depth located between a base of the sand dunes and a base of loose sand, autonomously moves under a surface of the loose sand along a predefined path, exchanges data with the surface station via an unspooling cable, and receives commands from the surface station via the unspooling cable. The GLRS transmits telemetry data from the one or more subsurface burrowing robots to the surface station. The GLRS comprises a first GLRS positioned on the base of the sand dunes and a second GLRS disposed on the one or more subsurface burrowing robots.

The application discloses a wireless node cooperative communication low-power control method based on distributed optical fiber sensing and belongs to the technical field of distributed optical fiber sensing and Internet of Things communication fusion. The method relies on a heterogeneous cooperative system composed of a distributed acoustic sensing (DAS) host, a center server and a wireless acoustic wave acquisition terminal, and realizes cooperative control through wireless terminal time synchronization, hardware silent cycle recording, adaptive wake-up instruction generation, historical data cross-border backtracking, narrowband feature extraction and heterogeneous data fusion decision. The application solves the problems of high energy consumption of wireless nodes, missing event starting data and bandwidth waste in the prior art, realizes low-power long-term deployment, complete event capture and high-reliability identification through on-demand wake-up and data processing guided by DAS, and is suitable for long-distance pipeline, power line and other safety monitoring scenes with strict requirements for real-time response and low power consumption.

There is provided a method and system of frequency dithered distributed acoustic sensing (FD-DAS) using group data signal processing, where the continuous wave (CW) coherent laser's optical frequency or optical phase for the FD-DAS interrogator may be set in evenly or randomly distributed manner for different data groups but they are kept as constant or with negligibly variation within each data group. Such FD-DAS may be used to improve acoustic or vibration signal measurement reliability, to allow to use a low-cost single-frequency laser such as a DFB laser, and / or to suppress polarization fading effect.

This invention discloses a method and system for extracting vehicle signals based on distributed acoustic sensing, comprising: acquiring raw spatiotemporal vibration signals collected along a road by a distributed fiber optic acoustic sensing system; performing bandpass filtering on the raw spatiotemporal vibration signals to obtain a preliminary filtered signal; superimposing the preliminary filtered signals in the time dimension within a preset time window to obtain a signal-enhanced superimposed signal; normalizing the signal amplitude of each sensing channel in the superimposed signal to obtain a normalized vibration signal; transforming the normalized vibration signal to the frequency-wavenumber domain; and applying a hard threshold filter to the frequency-wavenumber domain signal to remove irregular noise to obtain a first filtered signal. The method and system of this application improve the accuracy and robustness of extracting vehicle signals from complex road noise backgrounds.

This invention relates to a trajectory recognition method based on distributed acoustic sensing, belonging to the field of vehicle trajectory recognition technology. The trajectory recognition method based on distributed acoustic sensing utilizes a distributed acoustic sensing system to achieve high-precision quantitative measurement of external mechanical disturbances by demodulating the phase change of Rayleigh backscattered light. Its unique feature lies in that the trajectory recognition method includes the following steps: Step 1, acquiring low SNR vibration signals collected by the DAS system within a unit acquisition time; Step 2, in VTR Net, employing the Global-Local Feature Collaborative Modeling Mechanism (GL-FCM) and the Multi-Resolution Attention Feature Map Recovery Architecture (AG-FMR); Step 3, using the CEH-FA model robustness enhancement method for vehicle trajectory recognition to identify and finally output the vehicle trajectory.

There is provided a method and an apparatus of fiber optic distributed acoustic sensing (DAS) which can use low-cost coherent laser as well as low-cost acquisition and processing electronics and which can still provide reliable monitoring results for optical fiber monitoring and troubleshooting applications in optical fiber telecommunication networks. Such low-cost solution is made possible by employing grouped data signal processing. Data is processed over independent groups of data to provide an independent DAS signal for each group. This allows measurements to be less sensitive to laser fluctuations and thereby reduces coherent laser technical specification requirements and allows the use of a low-cost coherent laser (thereby reducing the cost of the laser) as well as low-cost acquisition and processing electronics.

The application discloses a kind of distributed acoustic sensing road cavity monitoring methods based on vehicle-induced vibration signal.The method is based on distributed acoustic sensing technology, first parameter initialization and obtain the distributed acoustic sensing signal sampling data sequence to be processed;Then the data is preprocessed and vehicle signal is enhanced;Vehicle trajectory parameters are extracted;On this basis, the correlation characteristics between distributed acoustic sensing channels are calculated using the extracted vehicle trajectory parameters to determine whether there is a cavity.This method makes full use of the all-weather perception and high resolution accuracy features of the distributed acoustic sensing array, and accurately monitors the road cavity with low computational complexity, suitable for large-scale real-time monitoring engineering applications.

The application discloses a kind of pulse modulation optical fiber distributed sound sensing earthquake monitoring method and system, comprising: by optical fiber to each seismic measuring point place transmission linear frequency modulation pulse light wave;Obtain the backscattering power waveform of Rayleigh light wave returned by optical fiber;The backscattering power waveform of Rayleigh light wave returned by optical fiber and the reference backscattering power waveform of Rayleigh light wave returned by optical fiber when there is no earthquake caused environmental vibration are compared, the time offset of waveform at each measuring point at different measuring times is determined;According to the time offset of waveform at each measuring point at different measuring times, the optical fiber stress level at each measuring point at different measuring times is determined;From the optical fiber stress level at each measuring point at different measuring times, extract the measurement data related to earthquake. Improve the precision of earthquake monitoring.

The application discloses a passive polarization fading resistant fiber-optic distributed acoustic sensing system, which comprises a polarization beam splitter for splitting back-reflected pulse light from a sensing fiber into two signal lights with orthogonal polarization states; first and second non-equal-arm interferometers for receiving the two signal lights respectively and generating three interference signals with a fixed phase difference respectively; three polarization beam combiners for performing polarization-orthogonal non-coherent beam combination on optical signals from corresponding ports of the two interferometers and outputting three combined optical signals; and a multi-channel photodetector and a processor for receiving and demodulating the combined optical signals to obtain dynamic phase changes of points along the sensing fiber. The application solves the problem of random weakening of signal amplitude of an interferometer type fiber-optic distributed acoustic sensing system caused by polarization fading, does not need active polarization control and complex post-processing algorithms, and significantly improves the reliability and long-term stability of the system.

This invention provides a fiber optic anti-loss coupling device and a method for multi-hole deployment in coal mines, belonging to the field of coal mine safety monitoring technology. Based on a PVC pipe with grooved outer wall and external and internal threads at both ends, and a grooved anti-bending guide assembly, this invention provides a fiber optic deployment device and method for drilling holes. It is suitable for the efficient and reliable deployment of distributed acoustic sensing (DAS) microseismic monitoring optical cables in coal mines, especially addressing the needs for improved bending resistance, tensile strength, and coupling quality of bottom-hole optical fibers under cement slurry sealing conditions. By improving the PVC pipe structure, guide structure, and sealing / sealing process, low-loss and high-coupling-efficiency fiber optic deployment in mines is achieved.

A distributed acoustic sensing (DAS) system may include an optical fiber, a phase-sensitive optical time domain reflectometer (φ-OTDR) coupled to the optical fiber and configured to collect DAS frequency domain spectral data therefrom having peaks therein, and a processor. The processor may cooperate with the φ-OTDR to process the DAS frequency domain spectral data to fit a polynomial curve to the DAS frequency domain spectral data, determine an acoustic event based upon the fitted polynomial curve, and generate an acoustic event report from the acoustic event.

This invention discloses a method and system for monitoring the operating status of a coal chuting pipeline based on distributed acoustic sensing. The method divides the coal chuting pipeline along its axial direction into several monitoring zones, and lays distributed acoustic sensing optical fibers along the outer wall of the pipeline along its axial direction. Continuous sampling is performed on the distributed acoustic sensing fibers along their length to obtain pre-processed acoustic signals within each time window of each monitoring zone. Frequency domain analysis is then performed, calculating the energy proportion of each frequency band and constructing feature vectors for each time window of each monitoring zone based on the main peak frequency, spectral entropy, spectral similarity, and impact amplitude characteristics in the spectral signal. An acoustic reference benchmark is established for each monitoring zone under normal coal flow impact conditions. The joint anomaly score for each time window of each monitoring zone is obtained by combining the feature vectors and the acoustic reference benchmark, and a joint temporal and spatial judgment is performed to determine the abnormal monitoring zone and anomaly type.

A system may include a first DAS station, comprising a first plurality of interrogator units to launch a first plurality of DAS signals in a first direction, wherein a first interrogator unit is configured to launch a first DAS signal at a first interrogation rate and first wavelength, wherein a second interrogator unit is configured to launch a second DAS signal at a second wavelength and second interrogation rate, less than the first interrogation rate. The system may include a loopback array, comprising a plurality of loopbacks, arranged over a plurality of spans, wherein a first set of proximate loopbacks nearest to the first DAS station are configured to route back the first DAS signal to the first DAS station, and wherein a first set of intermediate loopbacks, located further from the first DAS station, are configured to route back the second DAS signal to the first DAS station.

A hydraulic fracturing system and method trains a machine learning model to identify pressure communication events using LFDAS sensor data. The model is trained using information collected from the pressure gauges and information collected from the LFDAS to identify pressure communication events within LFDAS sensor data.

A method is described for automatically detecting shear-wave (S-wave) microseismic reflections using distributed acoustic sensing (DAS). The method includes obtaining raw DAS data; performing passive seismic event detection and phase picking; extracting a passive seismic event based on the passive seismic event phase picks to generate a seismic S-wave event gather; reducing noise in the raw DAS data; using the passive seismic S-wave event gather and the passive seismic event phases to identify an apex of a passive seismic S-wave event in the denoised DAS dataset and dividing it into two portions based on the apex; dip filtering the two portions to remove the direct arrival of the passive seismic S-wave events to generate a dip-filtered gather; and generating an S-wave microseismic reflection gather based on the dip-filtered gather.

This invention discloses a pipeline corrosion monitoring system, belonging to the field of distributed acoustic sensing, comprising sensing optical fibers, communication optical fibers, and a distributed acoustic sensing host. This invention uses a distributed optical fiber sensing host to collect signals from normal pipeline operation. The sensing optical fibers are divided into multiple sensing intervals. Each sensing interval includes a first sensing optical fiber unit that spirals back and forth in a wave pattern covering the outer side of the pipe wall under test, and a second sensing optical fiber unit along the axis. Data augmentation algorithms are used to improve the perception of the encapsulation structure and train an initial machine learning model. When the model determines that the signal deviates from the normal range, it is identified as suspected corrosion. High-precision location of the suspected corrosion point is achieved based on the index of the suspected corrosion sensing structure. This invention can enhance sensing sensitivity, improve construction efficiency, and achieve high-precision, intelligent identification and location of pipeline corrosion status without prior information.

The application discloses a kind of distributed acoustic sensing earthquake monitoring data stream processing method and system, belong to earthquake monitoring and data processing technical field.The method of the application includes: after the original earthquake monitoring data is preprocessed, it is sliced using sliding processing time window, and the data segment suitable for real-time detection is obtained;Design adaptive short-time average / long-time average detection algorithm, detect the data segment, and dynamically adjust the adaptive parameter in the algorithm according to the data characteristics;Finally, the initial candidate list of earthquake event is executed multi-channel fusion detection, to generate the final detection list of earthquake event.The application is based on distributed stream data processing architecture, combined with the innovative advantage of adaptive earthquake detection algorithm, can improve the accuracy of earthquake detection while ensuring the real-time of detection result, can provide efficient and reliable technical support for large-scale earthquake monitoring task.

An optical interrogation system for high definition-distributed acoustic sensing (HDDAS) of a vibration that changes a length of an optical fiber sensor in contact with a material or structure includes an optical interferometer, optical detection circuitry, coupled to the optical interferometer, for detecting optical interferometric measurement signals for a length of the optical fiber sensor, and data processing circuitry. The data processing circuitry receives interferometric measurement signals from the optical detection circuitry and generate, based on the interferometric measurement signals, interferometric measurement data for a length of the optical fiber sensor. It processes the interferometric measurement data to determine a strain state of the optical fiber sensor at one or more locations along the optical fiber sensor and determines a vibration component of the strain state of the optical fiber sensor at the one or more locations along the optical fiber sensor.

This invention discloses a method for identifying construction events based on inherent physical characteristics using distributed acoustic sensing (DAS) technology. The method first initializes parameters and acquires the DAS signal sampling data sequence to be processed. Then, it preprocesses the data from each channel, calculates the signal-to-noise ratio (SNR) of each channel, filters effective channels, eliminates abnormal data channels, and determines whether a significant construction event exists based on the number of effective channels. Next, it extracts the pulse density feature value of the effective data and determines whether it is a hammer event. If the condition is not met, it extracts feature values ​​such as the proportion of characteristic frequency band components, second harmonic content, and duty cycle to determine whether it is a cutting machine event. If the condition is still not met, it determines whether it is a pneumatic pick event through the tailing coefficient feature value, ultimately achieving accurate identification of road construction events.

A method for mapping acoustic properties of water bottom sediments includes penetrating a piling into the water bottom sediments at a first of a plurality of locations. A first distributed acoustic sensor is inserted adjacent to the first piling. A second piling is driven into sediments at a second location. Acoustic signals are detected at the first acoustic sensor while penetrating the second piling. The detecting is indexed to a depth of the second piling as it is driven. A second acoustic sensor is inserted adjacent to the second piling. Penetrating a piling, detecting acoustic signals at each acoustic sensor and inserting a sensor are repeated until a piling is driven at all the locations. The signals are used to generate a map of properties of the sediments bounded by the plurality of locations. The properties comprise attenuation excluding effects of diffractors in the sediments.

A device includes a narrow linewidth laser, a dual-parallel Mach-Zehnder modulator and an arbitrary waveform generator. The arbitrary waveform generator is connected to the dual-parallel Mach-Zehnder modulator, and is configured to generate the linear frequency modulation pulse sequence including a plurality of pulses with sequentially increased or decreased central frequencies, so as to drive the dual-parallel Mach-Zehnder modulator. A laser transmitted by the narrow linewidth laser is divided into two parts, one part serves as reference light, and the other part, as signal light, is modulated into the linear frequency modulation pulse sequence by the dual-parallel Mach-Zehnder modulator and then output to a sensing optical fiber. Rayleigh backscattered light generated in the sensing optical fiber interferes with the reference light. An interference signal is detected by a balanced photodetector and subsequently acquired by an acquisition card.

A distributed acoustic sensing system can include an optical interferometer. The optical interferometer can include a fiber coupler for splitting an optical light signal, and a fiber delay coil for introducing a controlled time delay in one of the paths. At least one path can form a loop, enabling controlled delay and temporary storage of light, resulting in an interference pattern. The system can gradually mitigate noise or distortion, improving sensitivity of defect detection and / or signal reception quality.

Systems and methods for generating a sensitivity map for a sensing fiber in relation to a monitored infrastructure are disclosed. One method includes: designing one or more event signals matching one

The application provides a heterodyne distributed acoustic wave sensing system based on frequency shift time gating and a demodulation algorithm, and belongs to the technical field of distributed acoustic wave sensing. A light coupling module divides continuous laser into two paths of signal light and local oscillator light. A light modulation module sequentially performs pulse modulation and frequency shift modulation on the signal light, and outputs the modulated light pulse. A sensing optical fiber receives the light pulse output by the light modulation module, and generates a backscattering signal based on the back Rayleigh scattering effect. A light mixing module coherently mixes the backscattering signal and the local oscillator light. A photoelectric detection module converts the coherently mixed light signal into an electric signal. A signal processing unit collects the electric signal and extracts vibration information at different positions of the optical fiber through a phase demodulation algorithm. The application realizes synchronous integration of pulse and frequency shift modulation, optimizes the demodulation algorithm, improves the system stability, sensing accuracy and response efficiency, reduces the hardware cost and energy consumption, and is suitable for multi-scene application through innovative light path design and signal processing strategy.

Methods for geothermal well planning and development are provided. This includes: installing fiber optic cables that extend within a plurality of shallow wells, wherein the fiber optic cables support both DTS measurements and DAS measurements; connecting DTS interrogators to the fiber optic cables and configuring the DTS interrogators to measure temperature profiles in the plurality of shallow wells over time; determining planned location of one or more geothermal wells that access a geothermal reservoir from the measured temperature profiles; selecting at least one shallow well to be used for DAS measurements; at each selected shallow well, disconnecting the DTS interrogator from the fiber optic cable at the shallow well and connecting a DAS interrogator to the fiber optic cable at the shallow well; and configuring the DAS interrogator at each selected shallow well to measure an acoustic profile in the selected shallow well over time.