scholarly journals Low Computational Cost Distributed Acoustic Sensing Using Analog I/Q Demodulation

Sensors ◽  
2019 ◽  
Vol 19 (17) ◽  
pp. 3753 ◽  
Author(s):  
Fei Jiang ◽  
Zixiao Lu ◽  
Feida Cai ◽  
Honglang Li ◽  
Zhenhai Zhang ◽  
...  
Keyword(s):  
Beat Frequency ◽  
Computational Cost ◽  
Digital Processing ◽  
Time Domain Reflectometry ◽  
Coherent Detection ◽  
Universal Method ◽  
Acoustic Sensing ◽  
Sensing Applications ◽  
Distributed Acoustic Sensing ◽  
Phase Demodulation

Distributed acoustic sensing based on phase-sensitive optical time-domain reflectometry (Φ-OTDR) has been widely used in many fields. Phase demodulation of the Φ-OTDR signal is essential for undistorted acoustic measurement. Digital coherent detection is a universal method to implement phase demodulation, but it may cause severe computational burden. In this paper, analog I/Q demodulation is introduced into the Φ-OTDR based DAS system to solve this problem, which can directly obtain the I and Q components of the beat signal without any digital processing, meaning that the computational cost can be sharply reduced. Besides, the sampling frequency of the data acquisition card can theoretically be lower than the beat frequency as the spectrum aliasing would not affect the demodulation results, thus further reducing the data volume of the system. Experimental results show that the proposed DAS system can demodulate the phase signal with good linearity and wide frequency response range. It can also adequately recover the sound signal sensed by the optical fiber, indicating that it can be a promising solution for computational-cost-sensitive distributed acoustic sensing applications.

Kilometer-range distributed acoustic sensing by time- expanded phase-sensitive time-domain reflectometry

2021 ◽  
Author(s):  
Miguel Soriano-Amat ◽  
Hugo F. Martins ◽  
Luis Costa ◽  
Sonia Martin-Lopez ◽  
Miguel Gonzalez-Herraez ◽  
...  
Keyword(s):  
Time Domain ◽  
Time Domain Reflectometry ◽  
Acoustic Sensing ◽  
Phase Sensitive ◽  
Distributed Acoustic Sensing

scholarly journals Recent Advances in Distributed Acoustic Sensing Based on Phase-Sensitive Optical Time Domain Reflectometry

2018 ◽  
Vol 2018 ◽  
pp. 1-16 ◽  
Author(s):  
Yonas Muanenda
Keyword(s):  
Time Domain ◽  
Time Domain Reflectometry ◽  
Fiber Optic Sensor ◽  
Acoustic Sensing ◽  
Rayleigh Backscattering ◽  
Recent Advances ◽  
Optical Time Domain Reflectometry ◽  
Phase Sensitive ◽  
Distributed Acoustic Sensing ◽  
Optical Time

Distributed acoustic sensing (DAS) using coherent Rayleigh backscattering in an optical fiber has become a ubiquitous technique for monitoring multiple dynamic events in real time. It has continued to constitute a steadily increasing share of the fiber-optic sensor market, thanks to its interesting applications in many safety, security, and integrity monitoring systems. In this contribution, an overview of the recent advances of research in DAS based on phase-sensitive optical time domain reflectometry (ϕ-OTDR) is provided. Some advanced techniques used to enhance the performance of ϕ-OTDR sensors for measuring backscattering intensity changes through reduction of measurement noise are presented, in addition to methods used to increase the dynamic measurement capacity of ϕ-OTDR schemes beyond conventional limits set by the sensing distance. Recent ϕ-OTDR configurations which significantly enhance the measurement spatial resolution, including those which decouple it from the probing pulse width, are also discussed. Finally, a review of recent advances in more precise quantitative measurement of an external impact based on frequency shift and phase demodulation methods using simple direct detection ϕ-OTDR schemes is given.

scholarly journals Hybrid demodulation method for distributed acoustic sensing based on coherent detection and pulse pair

2020 ◽  
Vol 13 (1) ◽  
pp. 012012 ◽  
Author(s):  
Wenjie Chen ◽  
Junfeng Jiang ◽  
Shuang Wang ◽  
Kun Liu ◽  
Zhe Ma ◽  
...  
Keyword(s):  
Coherent Detection ◽  
Acoustic Sensing ◽  
Pulse Pair ◽  
Distributed Acoustic Sensing ◽  
Demodulation Method

scholarly journals Localization and Discrimination of the Perturbation Signals in Fiber Distributed Acoustic Sensing Systems Using Spatial Average Kurtosis

Sensors ◽  
2018 ◽  
Vol 18 (9) ◽  
pp. 2839 ◽  
Author(s):  
Fei Jiang ◽  
Honglang Li ◽  
Zhenhai Zhang ◽  
Yixin Zhang ◽  
Xuping Zhang
Keyword(s):  
False Alarm ◽  
Signal To Noise Ratio ◽  
Moving Average ◽  
Spatial Dimension ◽  
Time Domain Reflectometry ◽  
Spatial Average ◽  
Acoustic Sensing ◽  
Sensing Systems ◽  
Distributed Acoustic Sensing ◽  
Optical Time

Location error and false alarm are noticeable problems in fiber distributed acoustic sensing systems based on phase-sensitive optical time-domain reflectometry (Φ-OTDR). A novel method based on signal kurtosis is proposed to locate and discriminate perturbations in Φ-OTDR systems. The spatial kurtosis (SK) along the fiber is firstly obtained by calculating the kurtosis of acoustic signals at each position of the fiber in a short time period. After the moving average on the spatial dimension, the spatial average kurtosis (SAK) is then obtained, whose peak can accurately locate the center of the vibration segment. By comparing the SAK value with a certain threshold, we may to some degree discriminate the instantaneous destructive perturbations from the system noise and certain ambient environmental interferences. The experimental results show that, comparing with the average of the previous localization methods, the SAK method improves the pencil-break and digging locating signal-to-noise ratio (SNR) by 16.6 dB and 17.3 dB, respectively; and decreases the location standard deviation by 7.3 m and 9.1 m, respectively. For the instantaneous destructive perturbation (pencil-break and digging) detection, the false alarm rate can be as low as 1.02%, while the detection probability is maintained as high as 95.57%. In addition, the time consumption of the SAK method is adequate for a real-time Φ-OTDR system.

scholarly journals Distributed Acoustic Sensing Using Chirped-Pulse Phase-Sensitive OTDR Technology

Sensors ◽  
2019 ◽  
Vol 19 (20) ◽  
pp. 4368 ◽  
Author(s):  
María R. Fernández-Ruiz ◽  
Luis Costa ◽  
Hugo F. Martins
Keyword(s):  
Direct Detection ◽  
Low Cost ◽  
High Sensitivity ◽  
Coherent Detection ◽  
Simple Method ◽  
Acoustic Sensing ◽  
Chirped Pulse ◽  
Distributed Sensor ◽  
Phase Sensitive ◽  
Distributed Acoustic Sensing

In 2016, a novel interrogation technique for phase-sensitive (Φ)OTDR was mathematically formalized and experimentally demonstrated, based on the use of a chirped-pulse as a probe, in an otherwise direct-detection-based standard setup: chirped-pulse (CP-)ΦOTDR. Despite its short lifetime, this methodology has now become a reference for distributed acoustic sensing (DAS) due to its valuable advantages with respect to conventional (i.e., coherent-detection or frequency sweeping-based) interrogation strategies. Presenting intrinsic immunity to fading points and using direct detection, CP-ΦOTDR presents reliable high sensitivity measurements while keeping the cost and complexity of the setup bounded. Numerous technique analyses and contributions to study/improve its performance have been recently published, leading to a solid, highly competitive and extraordinarily simple method for distributed fibre sensing. The interesting sensing features achieved in these last years CP-ΦOTDR have motivated the use of this technology in diverse applications, such as seismology or civil engineering (monitoring of pipelines, train rails, etc.). Besides, new areas of application of this distributed sensor have been explored, based on distributed chemical (refractive index) and temperature-based transducer sensors. In this review, the principle of operation of CP-ΦOTDR is revisited, highlighting the particular performance characteristics of the technique and offering a comparison with alternative distributed sensing methods (with focus on coherent-detection-based ΦOTDR). The sensor is also characterized for operation in up to 100 km with a low cost-setup, showing performances close to the attainable limits for a given set of signal parameters [≈tens-hundreds of pe/sqrt(Hz)]. The areas of application of this sensing technology employed so far are briefly outlined in order to frame the technology.

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