基于DFB激光器的振动传感系统改进PGC解调算法

Improved PGC Demodulation Algorithm for Vibration Sensing System Based on DFB Laser

相位生成载波(Phase Generated Carrier,PGC)解调算法是目前光纤干涉传感领域中重要的解调算法。针对目前PGC解调算法中光强扰动和调制深度影响信号解调准确度的问题,提出了一种改进的PGC解调算法(PGC-Ameliorated),并搭建了基于分布反馈(Distributed Feedback,DFB)激光器的振动传感系统进行实验验证。实验结果表明,当被测振动信号的频率为800Hz时,该算法信噪比为57dB,优于微分交叉相乘(Differential and Cross Multiplying,DCM)算法和反正切(Arctan)算法近20dB。在不同光强下,该算法解调信号幅值波动范围在±0.02rad;在不同调制深度下,该算法总谐波失真最小为0.61%,信纳比最大为25.9dB,相比于DCM算法和Arctan算法具有更低的总谐波失真和更高的信纳比。

The Phase Generated Carrier(PGC)demodulation algorithm is currently an important demodulation algorithm in the field of fiber optic interferometric sensing.To overcome the problem of light intensity perturbation and modulation depth affecting the accuracy of signal demodulation in the current PGC demodulation algorithm,an improved PGC demodulation algorithm(PGC-Ameliorated)is proposed,and a vibration sensing system based on Distributed Feedback(DFB)lasers is built for experimental verification.The experimental results show that when the frequency of the measured vibration signal is 800Hz,the signal-to-noise ratio of the algorithm is 57dB;this is better than those of the Differential and Cross Multiplying(DCM)and Arctan algorithms.At different values of light intensity,the amplitude of the demodulated signal fluctuates in the range of±0.02rad.At different values of modulation depth,the algorithm exhibits a minimum total harmonic distortion of 0.61%and a maximum signal-to-noise ratio of 25.9dB that provides lower total harmonic distortion and higher signal-to-noise ratio than the DCM and Arctan algorithms.