基于CLEAN算法的嫦娥四号低频射电频谱仪信号干扰抑制  

Signal Interference Suppression of Chang′e-4 Low Frequency Radio Spectrometer Based on CLEAN Algorithm

作　　者：刘晨迪 周建锋[4] 苏彦[1,2,3] Liu Chendi;Zhou Jianfeng;Su Yan(National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100101, China;University of Chinese Academy of Sciences, Beijing 100049, China;Key Laboratory of Lunar and Deep-Space Exploration, Chinese Academy of Sciences, Beijing 100101, China;Department of Engineering Physics, Tsinghua University, Beijing 100084, China)

机构地区：[1]中国科学院国家天文台,北京100101 [2]中国科学院大学,北京100049 [3]中国科学院月球与深空探测重点实验室,北京100101 [4]清华大学工程物理系,北京100084

出　　处：《天文研究与技术》2022年第3期206-220,共15页Astronomical Research & Technology

基　　金：国家自然科学基金(12073048)资助.

摘　　要：嫦娥四号低频射电频谱仪(Low Frequency Radio Spectrometer,LFRS)放置在月球背面,观测条件得天独厚。然而,嫦娥四号平台存在约10-15W/(m2·Hz)的强干扰,并且干扰在每道时域数据中存在明显差异,大大削弱了低频射电频谱仪的观测灵敏度。为此,从两组信号的相关性出发,提出基于CLEAN算法,借助互相关功率谱、傅里叶级数等工具,把低频射电频谱仪天线A,B和C的时域观测数据切分为强相关的CLEAN模型信号和部分相关的残余信号。其中,CLEAN模型信号主要由平台干扰信号和可能的低频强射电爆发组成;残余信号由接收机噪声、未扣除的平台干扰信号和常规低频射电信号组成。将该算法应用到实际数据中,结果表明,嫦娥四号低频射电频谱仪的未积分灵敏度可以提高约8个数量级,达到10-23W/(m2·Hz)。在此基础上,基于对平台干扰信号中确定成分和宽带随机成分的分类处理,借助低频射电爆发信号和平台干扰信号在功率谱上的不同表现,以及常规低频射电天文信号受月球自转调制等信息,将来科学分析工作的重点是进一步处理CLEAN模型信号和残余信号,以发现低频强射电天文爆发信号,对全天区进行粗略的成像。The Chang′e-4 low-frequency radio spectrometer is placed on the back of the moon,and its natural observation conditions are unique.However,the Chang′e-4 platform has strong interference of about 10-15W/(m2·Hz)level,and there are obvious differences in the interference in each channel of time domain data,which greatly weakens the astronomical observation sensitivity of the low-frequency radio spectrometer.To this end,starting from the correlation of the two sets of signals,this paper proposes to divide the time-domain observation data of the low-frequency radio spectrometer A,B,and C antennas into strongly correlated CLEAN model signals and partial correlated residual signal based on the CLEAN algorithm,with the help of cross-correlation power spectrum,Fourier series expansion and other tools.The CLEAN model signal is mainly composed of platform interference signals and possible low-frequency strong radio bursts;the residual signal is composed of receiver noise,undeducted platform interference signals and conventional low-frequency radio signals.Applying this method to actual data,the results show that the unintegrated sensitivity of the Chang′e-4 low-frequency radio spectrometer can be increased by about 8 orders of magnitude,reaching a level of 10-23W/(m2·Hz).On this basis,based on the separate processing of the deterministic components and broadband random components in the platform interference signal,and then relying on the different performance of the low frequency radio burst signal and the platform interference signal in the power spectrum,and the conventional low frequency radio astronomy signal modulated by the moon rotation and other information,the focus of future scientific analysis work is to further process the CLEAN model signal and residual signal,with a view to discovering low-frequency strong radio astronomy burst signals,and even roughly imaging the entire sky.

关 键 词：嫦娥四号低频射电频谱仪 平台干扰分离 CLEAN算法 

分 类 号：P16[天文地球—天文学]