- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
[IEEE 2018 International Carnahan Conference on Security Technology (ICCST) - Montreal, QC, Canada (2018.10.22-2018.10.25)] 2018 International Carnahan Conference on Security Technology (ICCST) - Reliable Leak Detection in Pipelines Using Integrated DdTS Temperature and DAS Acoustic Fiber-Optic Sensor
摘要： Reliable and early detection of leaks in pipelines transporting liquid or gas is highly desirable. In this work, two orthogonal technologies based on high-sensitivity fiber-optic distributed sensing were integrated into one system and tested for their effectiveness in actual field installations. The first technology is based on temperature difference detection using Distributed Differential Temperature Sensor (DdTS or DDTS). The second is based on Distributed Acoustic Sensor (DAS), which uses Coherent Optical Time-Domain Reflectometry (C-OTDR). DdTS can almost instantaneously detect a temperature difference in the optical fiber as low as 0.0005 οC, while C-OTDR can detect minute wide-bandwidth acoustic signals. Both technologies can detect the location of a leak to within a few meters. Experimental results for water and nitrogen gas leaks detected by the integrated system are presented for two different installations in the field – one where the cable was buried directly in the soil and another where the cable was buried in soil inside a 2” conduit for about 29 km. DdTS reliably detected leaks at both installations, while DAS detected leaks only when the cable was buried directly in soil. Test results show that the integration of both DdTS and DAS technologies can increase the probability of leak detection and minimize false/nuisance alarms. The integrated system also detected third party interference (TPI), thus providing a one-system solution for pipeline integrity monitoring and intrusion detection up to 40 km from a central location.
关键词： Oil and Gas Pipeline,DdTS,Leak Detection,Fiber Optics Sensor,DTS,TPI,DAS,C-OTDR
更新于2025-09-23 15:22:29
-
[IEEE 2018 41st International Conference on Telecommunications and Signal Processing (TSP) - Athens, Greece (2018.7.4-2018.7.6)] 2018 41st International Conference on Telecommunications and Signal Processing (TSP) - Experimental Verification of the Optimum Diagonal Loading Level for Adaptive Matched Filtering with ?-OTDR System
摘要： Recently, a temporal adaptive matched filtering technique has been proposed to reduce the background noise in phase-sensitive optical time domain reflectometry (φ-OTDR) systems deployed for fibre optic distributed acoustic sensing (DAS) applications. This technique utilizes noise covariance matrix inversion which is estimated from signal-free assumed training samples. The detection performance degradation due to desired signal presence in the training data and the ill-conditioning of the matrix because of the limited training data are conventionally avoided by adding some amount of white noise on the diagonal elements of the covariance matrix. In this paper, the optimum level for this diagonal loading (DL) is investigated for DAS applications and verified with real φ-OTDR data. The optimum DL level which has been analytically proven in beamforming applications is shown to be applicable in the temporal domain noise filtering for DAS applications. The experimental results validate that the optimum DL value is negative.
关键词： diagonal loading,phase-sensitive optical time domain reflectometry (OTDR),distributed vibration sensors,optimum filtering.,Adaptive matched filter
更新于2025-09-23 15:22:29
-
A hybrid distributed optical fibre sensor for acoustic and temperature fields reconstruction
摘要： We have proposed and experimentally demonstrated a distributed optical fibre sensor (DOFS) based on the hybrid of phase-sensitive optical time domain reflectometry (Ф-OTDR) and Raman optical time domain reflectometry (ROTDR), which could reconstruct the acoustic and temperature fields all along the sensing fibre at the same time. The Rayleigh back scattering (RBS), Raman Stokes (RS) and Raman anti-Stokes (RAS) generated by the probe pulse were separated by a WDM filter. Then the RBS was received by a heterodyne balanced photo detector (BPD) for quantitative vibration measurement and the dynamic acoustic field reconstruction, while the RS and RAS components were received directly by avalanche photodiodes (APDs) for temperature demodulation. The experimental results have shown that the proposed hybrid system could measure the temperature profile along a 12km long standard single-mode fibre with a maximal temperature uncertainty of 0.95℃ and a linearity response of R2=0.9986, along with a periodical knocking event detected simultaneously. Meanwhile, a 100Hz sinusoidal vibration at 12km distance along the same fibre could be clearly identified. Distributed knocking vibration and temperature was achieved at the same time with high accuracy.
关键词： temperature field,Distributed optical fibre sensors,acoustic field,Phase-sensitive OTDR (Ф-OTDR),Raman
更新于2025-09-23 15:21:01
-
Impact of Pulse Width on the Sensitivity and Range of a Raman-based Distributed Fiberoptic Temperature Sensor
摘要： This work presents the operation of a spontaneous Raman scattering-based distributed fiber-optic temperature sensor using a commercial OTDR and a standard EDFA optical amplification in a simple and economic scheme. We present both theoretical and experimental results regarding the sensor’s sensitivity and performance in seven different configurations, using OTDR pulses of 100 ns to 4000 ns for two detection regions, in the beginning and ending sections of a 27 km standard single-mode fiber sensor link. The results reveal the trade-off between sensor sensitivity, resolution and range, regarding the use of different OTDR pulsewidths.
关键词： Raman Scattering,optical sensor,Optical Fiber,OTDR,temperature sensor
更新于2025-09-19 17:15:36
-
Performance Optimization for Phase-Sensitive OTDR Sensing System Based on Multi-Spatial Resolution Analysis
摘要： This paper proposes and demonstrates a phase-sensitive optical time domain reflectometry (Φ-OTDR) sensing system with multi-spatial resolution (MSR) analysis property. With both theoretical analysis and an experiment, the qualitative relationship between spatial resolution (SR), signal-to-noise ratio (SNR) and the length of the vibration region has been revealed, which indicates that choosing a suitable SR to analyze the vibration event can effectively enhance the SNR of a sensing system. The proposed MSR sensing scheme offers a promising solution for the performance optimization of Φ-OTDR sensing systems, which can restore vibration events of different disturbance range with optimum SNR in merely a single measurement while maintaining the same detectable frequency range.
关键词： phase-sensitive optical time domain reflectometry (Φ-OTDR),signal-to-noise ratio (SNR),multi-spatial resolution (MSR) analysis
更新于2025-09-19 17:15:36
-
[IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Disturbed PD Detection System Based on Improved φ-OTDR Assisted by wFBG Array
摘要： A disturbed acoustic sensing system (DAS) based on improved φ-OTDR is proposed and experimentally demonstrated. A weak fiber Bragg grating (wFBG) array is introduced into sensing fiber to increase the signal to noise ratio (SNR) of system. In order to detecting the acoustic signals generated by partial discharge (PD) of 10KV power cables, the sensing fiber was packaged with an aluminium tape to enhance the sensitivity. The experimental results demonstrate the system performs well in demodulating PD signals, and has advantages of relatively high sensitivity and broadband frequency response.
关键词： weak fiber Bragg grating,Partial Discharge,φ-OTDR,acoustic detection
更新于2025-09-16 10:30:52
-
Lengthwise Measurement of Chromatic Dispersion along an Optical Fiber Transmission Link with Enhanced Correction Factor
摘要： In recent years optical time domain reflectometer (OTDR)-based techniques have become a known practice for measuring chromatic dispersion (CD) distribution along an optical fiber transmission link. In this paper, a measurement technique which uses a four-wavelength bidirectional OTDR to evaluate the CD distribution along the length of an optical fiber transmission system has been presented. A novel formulation has been developed for this nondestructive technique to improve the correction factor, which leads to an improvement in the CD and mode field diameter (MFD) measurement. The obtained experimental outcomes are in good agreement with those obtained by the interferometric technique.
关键词： backscattering,MFD,OTDR,chromatic dispersion
更新于2025-09-16 10:30:52
-
[IEEE 2019 2nd International Colloquium on Smart Grid Metrology (SMAGRIMET) - Split, Croatia (2019.4.9-2019.4.12)] 2019 2nd International Colloquium on Smart Grid Metrology (SMAGRIMET) - Fiber Optic Sensor Cable Based on Hollow Capillary Tube with Three Tightly Encapsulated Optical Fibers
摘要： Fiber optic sensor cable technology is relatively new field that combines a set of scientific and technical disciplines in a special way in order to meet industrial standards. In this paper we discuss one particular design for multipurpose and configuration multivalent optical fiber sensing. It has the potential to integrate more detection and measurement techniques in one cable body and this, in turn, largely contributes to installation cost optimization and directly impacts investment plans and industrial success. The article presents also a unique high-pressure high temperature lab facility conceptualized and constructed for testing and evaluation of this and similar optical fiber sensor cables.
关键词： fiber optic measurements,OFDR,acoustic sensors,BOTDA,BOTDR,DAS,Brillouin effect,optical fiber,pressure sensors,fully distributed optical fiber sensor,monitoring systems,strain sensors,temperature sensors,OTDR
更新于2025-09-16 10:30:52
-
Optical Fiber Communications (Principles and Applications) || Optical Measurements
摘要： Optical measurements are necessary to verify the operational characteristics of the optical fiber communication link. Various measurement techniques and special-purpose test equipments are employed for determining key performance parameters of the constituent components and devices including the optical fiber. It is quite obvious that optical measurements are needed at different levels of research and design, manufacturing and production of optical components and devices, installation and commissioning of optical fiber communication systems in the field. There is wide variety of optical measurement and test equipments used. These include optical power meter, optical oscilloscope and spectrum analyzer, optical time-domain reflectometer (OTDR), optical waveform analyzer, connector inspection microscope, dispersion analyzer, live fiber detector, talk-set, optical test set (combined source and power meter), etc. All these measurements are wavelength specific. Fiber attenuation and occurrence of faults in the optical fiber link is the main concern in ensuring the desired performance. There are several challenges involved with optical measurements like multiple wavelengths/channels, high optical power levels, need to carry tests remotely along with a high degree of automation.
关键词： OTDR,optical measurements,spectrum analyzer,optical power meter,optical fiber communications
更新于2025-09-12 10:27:22
-
Optical fiber microphones based on twice envelope demodulation algorithm
摘要： In order to improve the detection performance of a sound signal with the phase-sensitive optical time domain reflectometer, a demodulation algorithm based on twice envelope extraction is reported for the distributed sensing of sound signal. After the introduction of the sound sensing principle with the optical fiber microphone, a sensitivity enhancement structure which is composed by a piece of austenitic sheet is chosen for the detection of sound signal generated by the loudspeaker. The complete algorithm flow chart of twice envelope demodulation algorithm is then introduced. The first envelope extraction of the time-domain signal is acquired by the wavelet decomposition method in order to search the smooth region in the curve of time-domain signal. After the threshold comparison, the second envelope extraction of the smooth segment is realized by the envelope estimation algorithm, which could be used for the elimination of the noise factor. A high speed acquisition system based on FPGA is also proposed which could achieve signal acquisition through high speed AD acquisition module. The experimental results verify the effectiveness of the demodulation method. It can detect and locate the sound signal in the frequency range of 300 ?1 kHz at a distance of 1000 m with the position error within 20 m. This demodulation method provides a new solution for the detection of sound signal by the phase-sensitive optical time-domain reflectometer.
关键词： Optical fiber microphones,Envelope extraction,Sound sensing,Φ-OTDR
更新于2025-09-12 10:27:22