一种用于MCP成像探测器降噪的数字滤波器

Digital Filtering for Noise Reduction in MCP Imaging Detectors

基于微通道板(micro-channel plate,MCP)的单光子成像探测器是应用于电离层光学遥感探测及深空光学探测的主流探测器之一,MCP成像探测器运行于外太空非平稳环境时,探测器的观测信号受到高斯、非高斯噪声污染,引起观测信号信噪比降低,导致探测器成像质量下降.针对传统模拟滤波方式难以兼顾观测信号的降噪效果以及系统的计数率、基于模拟电路的滤波方式难以滤除后级电路引入的噪声等问题,提出了一种基于级联结构的数字滤波器对观测信号进行降噪.该方法先使用递推最小二乘(recursive least-squares,RLS)滤波器对观测信号进行初级滤波,经RLS滤波器降噪后的信号输入滑动平均(moving average,MA)滤波器进行平滑处理,最终获得高信噪比的输出信号.为了测试RLS-MA滤波器的降噪效果,针对不同信噪比的观测信号,分别使用最小均方(least mean square,LMS)、RLS、MA以及RLS-MA滤波器进行降噪对比,结果表明RLS-MA滤波器的输出信号具有更高的信噪比和更低的均方根误差.

The micro-channel plate(MCP)imaging detector is a main detector used widely in detection of weak signals such as planetary atmospheric airglow and aurora.Detected from the unstable condition of outer space,the desired signal of MCP detector is mainly corrupted by Gaussian and non-Gaussian noise,which results in signal-to-noise ratio decrease and imaging quality deterioration.Due to the conventional filtering methods based on analog circuits can hardly control both the noise reduction effects of the signal and the count rate of the system at the same time,and cannot filter out the noise introduced by the post-stage circuit,a digital filter on the basis of a cascade structure was proposed for noise reduction of the observed signal.The method was arranged to carry out primary filtering firstly for the detected signals by a recursive least squares(RLS)filter,and then to input the filtered signals into a moving average(MA)filter for further smoothing,so as to get a high signal-to-noise ratio output signal.In order to test the noise reduction effect of the proposed RLS-MA filter,a comparison study was conducted among the least mean square(LMS),RLS,MA and RLS-MA filters with different signal-to-noise ratio signal inputs.The results show that the output signal of the RLS-MA filter is provided with higher signal-to-noise ratio and lower root mean square error.