基于光纤中瑞利散射的特性，在光频域反射（optical frequency domain reflectometry，OFDR）系统中通过对信号进行互相关分析可以实现振动信号的分布式测量.在基于互相关算法的OFDR分布式光纤振动传感系统中，采用了重叠的移动窗对信号进行分段，并通过实验对比选取了合适的广义互相关算法的加权函数.实验表明，所提方法提高了系统的定位精度，降低了虚警率.系统的定位精度可达0.247 m，可测振动频率范围为5～50 kHz.
Based on characteristics of Rayleigh scattering light, one can achieve distributed measurements based on the correlation analysis of signals in the optical frequency domain reflectometry (OFDR) system. In this paper, we propose to apply overlapped sliding window in the subsections of signals and choose appropriate weighted function of generalized cross-correlation algorithm through experimental comparison in an OFDR distributed fiber-optic vibration sensing system based on cross-correlation algorithm. Experimental results show that by using the proposed technique, the OFDR performs with an improved positioning accuracy and a reduced false alarm rate. Furthermore, a distributed vibration sensor with the positioning accuracy of 0.247 m and the measurable vibration frequency ranging from 5 kHz to 50 kHz is demonstrated.
[1] Li H N, Li D S, Song G B. Recent applications of fiber optic sensors to health monitoring in civil engineering[J]. Steel Construction, 2004, 26(11):1647-1657.
[2] 杨明红, 王高鹏, 代吉祥, 等. 面向应用的光纤氢气传感技术[J]. 应用科学学报, 2018, 36(1):1-19. Yang M H, Wang G P, Dai J X, et al. Application-oriented fiber optic hydrogen sensing technology[J]. Journal of Applied Sciences, 2018, 36(1):1-19. (in Chinese)
[3] Bao X Y, Chen L. Recent progress in distributed fiber optic sensors[J]. Sensors, 2012, 12(7):8601-8639.
[4] 蔡海文, 叶青, 王照勇, 等. 分布式光纤声波传感技术研究进展[J]. 应用科学学报, 2018, 36(1):41-58. Cai H W, Ye Q, Wang Z Y, et al. Progress in research of distributed fiber acoustic sensing techniques[J]. Journal of Applied Sciences, 2018, 36(1):41-58. (in Chinese)
[5] 王东宁, 陈未萍, 刘烨, 等. 微型光纤线上/线内实验室[J]. 应用科学学报, 2018, 36(1):176-208. Wang D N, Chen W P, Liu Y, et al. Miniature lab on/in fiber[J]. Journal of Applied Sciences, 2018, 36(1):176-208. (in Chinese)
[6] Arbel D, Eyal A. Dynamic optical frequency domain reflectometry[J]. Optics Express, 2014, 22(8):8823-8830.
[7] Leviatan E, Eyal A. High resolution DAS via sinusoidal frequency scan OFDR (SFS-OFDR)[J]. Optics Express, 2015, 23(26):33318-33334.
[8] Shiloh L, Eyal A. Sinusoidal frequency scan OFDR with fast processing algorithm for distributed acoustic sensing[J]. Optics Express, 2017, 25(16):19205-19215.
[9] Zhou D P, Qin Z G, Li W H, et al. Distributed vibration sensing with time-resolved optical frequency-domain reflectometry[J]. Optics Express, 2012, 20(12):13138-13145.
[10] Ding Z Y, Yao X S, Liu T G, et al. Long-range vibration sensor based on correlation analysis of optical frequency-domain reflectometry signals[J]. Optics Express, 2012, 20(27):28319-28329.
[11] Knapp C H, Carter G C. The generalized correlation method for estimation of time delay[J]. IEEE Transactions on Acoustics Speech & Signal Processing, 2003, 24(4):320-327.
