基于自适应滤波的干扰消除方法研究

射电天文信号非常微弱,电磁环境对射电望远镜观测至关重要,通常可以利用地形、建立无线电宁静区、进行电磁屏蔽与防护等手段来减小电磁干扰.然而,仍有一些干扰难以屏蔽.故提出了一种基于自适应滤波的干扰消除方法,可用于复杂噪声环境中天文信号的提取.该方法借助自适应横向滤波器,采用最小均方(Least Mean Square, LMS)误差算法,以系统误差和收敛性为评判标准,通过改变步长与阶数对滤波效果进行优化,仿真结果显示该滤波器能在保证算法收敛的前提下有效提取信号.为了检验该算法的有效性,选取了新疆天文台南山26 m射电望远镜和Parkes 64 m射电望远镜记录的观测数据,采用设计的滤波器分别对不同的实测数据进行测试,验证了该滤波器的有效性.理论分析与实验结果一致表明该方法能有效消除天文观测中的干扰信号,具有一定的实用性.

A Research of RFI Mitigation Method Based on Adaptive Filter

Radio astronomical signals are very weak, so the electromagnetic environment is very important for radio astronomical observations. Usually, electromagnetic interference can be reduced by means of favorable terrain, establishing radio quiet area, electromagnetic shielding and protection, etc. However, there are still some RFIs (Radio Frequency Interferences) that are difficult to block out. This paper proposed an RFI mitigation method with the adaptive filter, which can be used to extract astronomical signals in complex noise environment. It adopts adaptive transverse filter and the least mean square (LMS) error algorithm by changing the order and step size to optimize the filtering effect. The evaluation criteria are systematic errors and convergent performance. The simulation results show that the filter can effectively extract the signal while ensuring the convergence of the algorithm. In order to test the effectiveness of the algorithm, the observation data recorded by Nanshan 26 m radio telescope of Xinjiang Astronomical Observatory and Parkes 64 m radio telescope are selected, and the designed filter is used to test different measured data to verify the effectiveness of the filter. The agreement between theoretical analysis and experimental results shows that this method can effectively eliminate the interference signals in the astronomical observation and has certain practicabilities.