FBG解调实时校正技术研究

Research on Real-time Correction Technique of FBG Demodulation

在基于可调谐F-P的FBG解调系统中,由于驱动电压与扫描波峰的关系不固定,增加了系统误差。为此研究了实时校正技术。首先,通过方案比较和分析,设计了并联型的实时校正系统,此系统可以通过多个参考点实时校正PZT的非线性问题以及可调谐F-P滤波器的结构性误差。然后,通过实验分析了PZT驱动电压与可调谐F-P波峰的关系,设计了快速分段算法。最后,针对此系统,设计了以现场可编程门阵列(FPGA)为核心的信号处理单元,将解调系统的控制、滤波计算和数据压缩等电路集成在FPGA芯片内部,保证了系统的实时性。实验结果表明,该系统的均方误差为2.2pm,最大误差为6pm。解决了此类解调系统受可调谐F-P滤波器精度限制的问题,提高了测量精度。

In the FBG demodulation system based on tunable fiber Fabry-Perot（F-P） interferometer,the system error increases due to the relationship of the driving voltage and the scanning wave peak,so the correction technology is studied in this paper.Firstly,a parallel real-time correction system is designed based on scheme comparison and analysis.This system corrects nonlinear problems of PZT and structural errors of the tunable FP interferometer using multiple reference points.Secondly,the relation between PZT driving voltage and the peak of tunable FP interferometer is analyzed by experiments.Then a fast segmentation algorithm is designed.Finally,a signal processing unit using field programmable gate array（FPGA） as the core is designed.This unit can guarantee real time work by integrating the demodulation system control,filter calculation and data compression circuits into one FPGA chip.Experimental results show that the mean square error of the system is 2.2 pm and the maximum error is 6 pm.Also the system measurement accuracy is improved,which solves the problem caused by accuracy limitation of the tunable FP interferometer.