毫米波宽带太阳射电观测系统的信号平坦度补偿方法  

Compensation method of signal flatness for a broadband solar millimeter radio observation system

作　　者：徐珂[1] 尚自乾 严发宝 刘洋 武昭[1] 张园园[1] 张磊[1] 苏艳蕊 陈耀[1] XU Ke;SHANG ZiQian;YAN FaBao;LIU Yang;WU Zhao;ZHANG YuanYuan;ZHANG Lei;SU YanRui;CHEN Yao(Laboratory for Electrom Agnetic Detection(LEAD),Institute of Space Sciences,Shandong University,Weihai 264209,China;School of Mechanical,Electrical&Information Engineering,Shandong University,Weihai 264209,China;CAS Key Laboratory of Solar Activity,National Astronomical Observatories,Chinese Academy of Sciences,Beijing 100012,China)

机构地区：[1]山东大学空间科学研究院空间电磁探测技术实验室,威海264209 [2]山东大学机电与信息工程学院,威海264209 [3]中国科学院太阳活动重点实验室,北京100012

出　　处：《中国科学：技术科学》2021年第4期413-423,共11页Scientia Sinica(Technologica)

基　　金：国家自然科学基金(批准号:41904158,11703017,11803017,41774180);中国博士后科学基金(编号:2019M652385);中国科学院太阳活动重点实验室开放基金(编号:KLSA201907);山东大学(威海)青年学者未来计划(编号:20820201005)资助项目。

摘　　要：在太阳射电观测系统中,接收机作为核心部分将天线接收到的太阳射电信号进行放大、滤波、数字化处理等操作后生成射电频谱.但接收机内部各种器件的幅频特性不一致性将导致接收机输出信号失真,这种失真在宽带信号时更加严重,使系统输出信号平坦度变差,进而影响观测系统数据的准确性.通过分析,信号不平坦主要来源于系统固定增益的不平坦度及随机噪声.针对这一问题,本文提出一种应用于毫米波宽带太阳射电观测系统的信号平坦度补偿方法.首先,将观测信号减去背景辐射噪声尝试补偿系统固定增益的不平坦度.随后,针对宽带信号利用分位图分析系统固定增益的不平坦度补偿是否完成,视不同情形进行下一步处理:(1)若分位图不符合正态分布,则需重新选取背景数据进行补偿操作直至分位图符合正态分布或超过尝试次数后丢弃这组数据;(2)若分位图符合正态分布,可认为系统固定增益的不平坦度补偿完成.最后,根据信号的方差和均值拟合得到白噪声函数积分次数与噪声抑制的关系,进而选择合适的积分次数抑制噪声以得到符合平坦度要求的补偿后信号.该模拟结果可对上位机实时数据处理算法提供参考,在高带宽内对信号的平坦度进行补偿,使接收机获取较为准确的观测数据(精细动态频谱).该方法已应用于山东大学槎山太阳射电观测站的35~40 GHz宽频太阳射电观测系统,并得到了较好的补偿效果.In a solar radio observation system,the receiver,as an essential instrument,processes the solar radio signal received by the antenna with amplification,filtering,digitization,and so on,and yields the solar radio dynamic spectrum.However,the amplitude–frequency inconsistencies of devices inside the receiver may lead to distortion of the output.In particular,the distortion increases when a broadband signal is processed by the receiver,and high uncertainty may appear.To solve this problem,in this paper we present a compensation method for the signal flatness for a solar microwave observing system.According to the analysis,the fluctuation of the signal flatness is caused by fluctuation of the gain with frequency and the random noise introduced by the system.First,we compensate the unflatness of the gain by subtracting the background signal from the observed signal.Quantile–quantile plots are then used to assess the compensation effect,and a new round of compensation is reprocessed if the plots do not follow a normal distribution.The integration times of the signals are finally deduced to reduce the random noise on account of the relationship between the integration times and noise depression.A simulation experiment can provide a good resolution for real-time data processing.This method has been used in the 35–40 GHz broadband solar radio observation system in the Chashan Solar Radio Observatory of Shandong University and demonstrates good stability and application potential.

关 键 词：太阳射电观测系统 信号平坦度 数据分析 

分 类 号：P161[天文地球—天文学] P182.2