Zhang Yixin, Liu Jingxiao, Xiong Fei, Zhang Xuping, Chen Xiaohong, Ding Zhewen, Zheng Yunyin, Wang Feng, Chen Mengmeng
College of Engineering and Applied Sciences, Nanjing University, Gulou District, Nanjing 210093, China.
Key Laboratory of Intelligent Optical Sensing and Manipulation, Ministry of Education, Nanjing University, Nanjing 210093, China.
Sensors (Basel). 2021 Mar 1;21(5):1694. doi: 10.3390/s21051694.
Phase-sensitive time-domain reflectometry (Φ-OTDR) can be used for fully distributed long-distance vibration monitoring. There is a fading phenolmenon in the Φ-OTDR, which will cause the signal intensity somewhere to be too low to extract the phase of the signal without distortion. In this paper, the Φ-OTDR based on space-division multiplexing (SDM) is proposed to suppress fading and we used multi-core optical fiber (MCF) to realize SDM. While inheriting the previous optimization strategy, we proposed a strategy based on frequency spectral similarity to process multiple independent signals obtained by SDM. And we compared the two methods. Through the experiments, the distortion rate can be reduced from an average level of 9.34% to less than 2% under continuous running of 270 s, which proves that SDM is a reliable technical route to achieve fading suppression. This method can effectively improve the fading suppression capability of the existed commercial systems.
相敏时域反射仪（Φ-OTDR）可用于全分布式长距离振动监测。在Φ-OTDR中存在衰落现象，这会导致某处信号强度过低，无法无失真地提取信号相位。本文提出基于空分复用（SDM）的Φ-OTDR来抑制衰落，我们使用多芯光纤（MCF）来实现SDM。在继承先前优化策略的同时，我们提出了一种基于频谱相似性的策略来处理通过SDM获得的多个独立信号。并且我们比较了这两种方法。通过实验，在连续运行270 s的情况下，失真率可从平均水平的9.34%降低到2%以下，这证明SDM是实现衰落抑制的可靠技术途径。该方法可有效提高现有商业系统的衰落抑制能力。
