Wang Qinglin, Bai Qing, Liang Changshuo, Wang Yu, Liu Yuting, Jin Baoquan
Opt Express. 2022 Mar 28;30(7):11604-11618. doi: 10.1364/OE.456620.
A random coding method for a Brillouin optical time domain reflectometer (BOTDR) fiber sensor is proposed. In this method, a series of pulses modulated by random code are injected into the optical fiber to enhance the signal-to-noise ratio (SNR) and further improve the measurement accuracy. Random coding method allows the sensing range to be extended to several tens of kilometers while maintaining meter-scale spatial resolution and lower detection peak power, without modifying the conventional configuration of BOTDR. The decoding principle and the coding gain of random coding method are analyzed and simulated. We experimentally implement the method and evaluate its influence on the performance optimization of BOTDR. Compared with the single pulse with peak power of 10 mW, the measured BFS uncertainty over 4.93 km sensing fiber is reduced from 5.34 MHz to 0.38 MHz when 512-bit random coding pulses with the same peak power are utilized. The experimental results show that the coding gain of 11.93 dB is obtained by 512-bit random coding. Benefitting from the SNR enhancement, the sensing range is extended from 4.93 km to 64.76 km within a root-mean-square error (RMSE) of 3 MHz, when the pulse peak power is only 10 mW and the spatial resolution is 2 m.
提出了一种用于布里渊光时域反射仪（BOTDR）光纤传感器的随机编码方法。在该方法中，将一系列由随机码调制的脉冲注入光纤，以提高信噪比（SNR）并进一步提高测量精度。随机编码方法可在不改变BOTDR传统配置的情况下，将传感范围扩展到几十公里，同时保持米级空间分辨率并降低检测峰值功率。分析并模拟了随机编码方法的解码原理和编码增益。我们通过实验实现了该方法，并评估了其对BOTDR性能优化的影响。与峰值功率为10 mW的单脉冲相比，当使用具有相同峰值功率的512位随机编码脉冲时，在4.93 km传感光纤上测得的布里渊频移（BFS）不确定度从5.34 MHz降低到0.38 MHz。实验结果表明，512位随机编码可获得11.93 dB的编码增益。受益于信噪比的提高，当脉冲峰值功率仅为10 mW且空间分辨率为2 m时，在均方根误差（RMSE）为3 MHz的情况下，传感范围从4.93 km扩展到64.76 km。
