基于数字滤波的光纤光栅传感信号去噪及其FPGA实现

摘要

Fiber Bragg grating sensor makes acquisition to physical change by detecting the FBG central wavelength drift caused by physical change ,while the wavelength detection precision is limited by noises .To improve the detection precision in noisy circumstance ,this paper suggests that the digital filter wave to denoise .By analyzing the ability of denoising for FIR low‐pass filter with various window functions ,it is discovered that the Kaiser window has a better performance in pass‐band ripple ,stopband attenuation ,SNR and MSE ,so that its order and βparameters are determined .The designed wave filter is used to carry out the de‐noising treatment of the FBG re‐flection spectrum with good results obtained ,particularly in the peak value of wavelength .So that the FBG reflection spectrum is rather smooth and the resolution ability of peak value wave‐length is obviously improved .Finally the PPGA is used to realize FIR filter wave and to denoise fiber Bragg grating sensing signal ,and the designed FIR wave filter has further been tested to have a better denoising effects .%光纤光栅传感器是通过检测被测物理量引起的光纤光栅中心波长的漂移量来得到该物理量的变化，波长检测精度常受到各种噪声的限制。为了提高波长的检测精度，本文提出采用数字滤波进行去噪。分析了不同窗函数 FIR低通滤波器对光纤光栅传感信号去噪能力的影响，发现凯泽（Kaiser ）窗的通带纹波、阻带衰减以及去噪后的信噪比和均方误差均比较好，并确定了其阶数和β参数。用设计的滤波器对光栅反射谱进行了去噪处理，效果较好，尤其是在峰值波长处，光栅反射谱较平滑，峰值波长的分辨能力显著提高。最后用FPGA实现FIR滤波并对光纤光栅传感信号去噪，进一步验证了设计的FIR滤波器对光栅传感信号具有良好去噪效果。