自适应噪声谱估计抵消技术及其应用

为扩大虚拟暗室EMI(electromagnetic interference,电磁干扰)测试系统的应用范围,提高系统测量精度,改善其在复杂环境下的测试效果,借助自适应滤波及维纳滤波理论对基于传统自适应噪声抵消模型建立的测试系统进行分析,传统测试系统的参考通道存在的设备辐射分量制约了系统应用范围,从而不能实现任意信噪比环境下的高精度测量.同时,提出基于谱估计的自适应噪声抵消模型,该模型建立的虚拟暗室系统通过对测试系统主通道信号进行谱估计,得到设备辐射信号及噪声信号的功率谱密度,并根据该功率谱密度对参考通道信号进行针对性抑制,以滤除参考通道辐射信号分量,从而提高测试系统的适用性及精度.仿真实验表明:该方法在高、低信噪比环境下均能准确地提取设备辐射信号并准确复现受试设备的辐射信号,提高了虚拟暗室系统对环境噪声的抑制能力,增强了虚拟暗室系统的环境适应性.

Research on automatic noise spectral estimation suppression technique and its application

In order to expand the application range of the virtual chamber measurement system, improve the measurement precision in actual measurement, a mathematical method of adaptive filtering and wiener filtering is used to analyze the inherent defects of the measurement system based on traditional ANS (automatic noise suppression), and point out the main factor restricted the application range and measurement precision is the existence of source signal component which is detected in the reference channel. According to the analysis result, the measurement system is rebuilt, coming up an ANS based on spectral estimation. Analyzing the mixed signal detected in the main channel, the remodeled system can get the PSD (power spectrum density) of radiation signal and noise signal .According to the frequency of the peak point in the PSD, notch filter has been designed to filter the radiation signal component captured by reference channel, then the system meets its expectation. The simulation and experiment results show that this method shows good performance in the high SNR (signal noise ratio) measurement circumstance as well as low SNR, which means that extracting the radiation signal of equipment under test exactly, high noise suppression ability and environmental adaptability of virtual chamber.