基于DDS信号和插值法的FBG解调系统研究

Research on FBG demodulation system based on DDS signal and interpolation method

针对F-P滤波器解调法容易产生漂移与校正成本较高的问题,本文采用FPGA和光开关搭建了F-P滤波器多通道共振解调系统,该系统利用DDS信号生成特定的三角波驱动电压,通过串联多维参考FBG实现基于插值法对波长-时间的动态标定,设定了3种动态标定模式,包含线性关系和二次关系的标定。利用FPGA控制光开关实现快速切换模式与参考波长、待测波长信号的分步采集,3种模式100 Hz平均偏差分别为0.02802 nm、0.01814 nm、0.0109 nm。研究结果表明,在单位电压(1 V)下,相对于静态标定,误差降低45%以上,提高解调精度并且降低校正成本,同时解决参考与待测波长数值过近时容易导致的误判问题。

To address the issue of drift and the high cost of calibration in the F-P filtering demodulation method,this paper had developed a F-P filter multi-channel resonance demodulation system using the FPGA and the fiber optic switch.The system utilizes DDS signals to generate specific triangular wave driving voltages and achieves dynamic calibration of wavelength-time by linking multiple-dimensional reference FBGs in series.Three dynamic calibration modes,including linear and quadratic relationships,are set.The FPGA-controlled fiber optic switch enables fast channel switching of modes and step-by-step acquisition of reference wavelength and wavelength signal to be measured.he average deviations in the three modes are 0.02802 nm,0.01814 nm,and 0.0109 nm,respectively,at a frequency of 100 Hz.The research results indicate that,under a unit voltage of 1 V,the deviation is reduced by over 45%compared to static calibration,improving the demodulation accuracy Improves demodulation accuracy,reduces calibration costs and addressing the issue of misjudgment caused by the proximity of the reference and measured wavelengths.