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提出并实现了一种用于微弱极低频信号探测的干涉式光纤传感器相位生成载波(PGC)解调方法。对PGC解调方法中微分交叉相乘(DCM)及反正切(Arctangent)两种相位抽取算法应用于极低频信号解调进行了理论分析和算法仿真,其结果表明,DCM式PGC算法解调极低频信号时,其结果中存在直流漂移,而Arctangent式PGC算法的解调结果中不存在直流漂移问题。进而基于光纤干涉仪搭建了极低频光纤传感系统,并进行了两种PGC解调算法的对比实验,实验结果表明,Arctangent式PGC算法不存在DCM式PGC算法解调极低频信号时的直流漂移,且能够准确解调极低频信号,与理论分析的结论相符。最后采用Arctangent式PGC算法实现了极低频干涉式光纤传感系统,该系统达到的最低可探测信号频率为0.01 Hz,最小可探测信号为4×10-4rad/Hz,动态范围为110 dB@1 Hz,线性相关系数为99.99%。
An interferometric fiber sensor phase-generated carrier (PGC) demodulation method is proposed and implemented for the detection of weak and very low frequency signals. The theoretical analysis and algorithm simulation of differential phase-interleaved (DCM) and arctangent phase-decimation algorithms applied to the demodulation of very low frequency signals in the PGC demodulation method are presented. The results show that the demodulation pole When there is a low-frequency signal, there is a DC drift in the result, but there is no DC drift problem in the demodulation result of the Arctangent PGC algorithm. Furthermore, an ultra-low frequency optical fiber sensing system based on optical fiber interferometer was built and compared with two kinds of PGC demodulation algorithms. The experimental results show that the Arctangent PGC does not exist DC-PGD , And can accurately demodulate the very low frequency signal, consistent with the theoretical analysis of the conclusion. Finally, Arctangent PGC algorithm was used to realize extremely low frequency interferometric fiber optic sensing system. The system achieves the minimum detectable signal frequency of 0.01 Hz, the minimum detectable signal of 4 × 10-4 rad / Hz and the dynamic range of 110 dB @ 1 Hz, the linear correlation coefficient is 99.99%.