Phase demodulation method based on a dual-identical-chirped-pulse and weak fiber Bragg gratings for quasi-distributed acoustic sensing

2020 ◽  
Vol 8 (7) ◽  
pp. 1093 ◽  
Author(s):  
Guanhua Liang ◽  
Junfeng Jiang ◽  
Kun Liu ◽  
Shuang Wang ◽  
Tianhua Xu ◽  
...  
Keyword(s):  
Fiber Bragg Gratings ◽  
Bragg Gratings ◽  
Acoustic Sensing ◽  
Chirped Pulse ◽  
Distributed Acoustic Sensing ◽  
Demodulation Method ◽  
Phase Demodulation

Quasi-distributed acoustic sensing based on identical low-reflective fiber Bragg gratings

2016 ◽  
Vol 28 (1) ◽  
pp. 015202 ◽  
Author(s):  
Ying Shang ◽  
Yuan-Hong Yang ◽  
Chen Wang ◽  
Xiao-Hui Liu ◽  
Chang Wang ◽  
...  
Keyword(s):  
Fiber Bragg Gratings ◽  
Bragg Gratings ◽  
Acoustic Sensing ◽  
Distributed Acoustic Sensing

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.

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 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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