VLBI观测双线极化条纹拟合方法  

A dual linear polarization fringe fitting method for VLBI observation

作　　者：黄逸丹[1] 刘磊[1,2,3] 舒逢春[1,2,3] 郑为民 HUANG Yidan;LIU Lei;SHU Fengchun;ZHENG Weimin(Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai 200030, China;Key Laboratory of Radio Astronomy, Chinese Academy of Sciences, Nanjing 210008, China;Shanghai Key Laboratory of Space Navigation and Positioning Techniques, Shanghai 200030, China)

机构地区：[1]中国科学院上海天文台,上海200030 [2]中国科学院射电天文重点实验室,江苏南京210008 [3]上海市导航定位重点实验室,上海200030

出　　处：《测绘学报》2020年第4期423-431,共9页Acta Geodaetica et Cartographica Sinica

基　　金：国家自然科学基金(11573056,11573057,11903067,11973011);国家科技基础条件平台项目“国家基础科学数据共享服务平台”(DKA2017-12-02-09);上海市空间导航与定位技术重点实验室课题(ZZXT-201902)。

摘　　要：提出了一种可用于下一代VLBI观测系统(VGOS)的双线极化条纹拟合方法。现有的VLBI观测模式采用的是右圆极化(RCP),而VGOS系统采用的是双线极化。本文方法包括校正和组合条纹拟合两部分。校正部分选择一颗强源作为参考源,分别得到不同极化方式下的通道时延及相位校正数据,用于目标源的校正。组合条纹拟合部分将4种极化分量的可见度数据组合成伪Stokes分量,通过搜索差分星位角使伪Stokes分量的幅值达到最大,从而获得最终的时延观测量。与单极化条纹拟合相比,组合极化获得的条纹具有更高的信噪比(SNR)及更小的条纹相位弥散度。In this paper,we propose a dual linear polarization fringe fitting method which can be used in the next generation VLBI system(VLBI global observing system,VGOS).The legacy geodetic VLBI observation mode is dedicated to the right circular polarization(RCP),which differs from the dual linear polarization adopted in the VGOS system.The algorithm presented in this work consists of the calibration part and combined fringe fitting part.In the calibration part,we derive the intermediate frequency(IF)delay and phase calibration information from each polarization product by carrying out fringe fitting on a strong reference source.Then this information is applied to the target sources.In the combined fringe fitting part,we combine 4 polarization products into the Pseudo-Stokes Intensity and in the meanwhile search for the appropriate differential parallactic angle,so as to maximize the amplitude of the intensity and therefore derive the delay as observable.Compared with single polarization,the combined product yields higher signal-to-noise ratio(SNR)and smaller fringe phase scatter.

关 键 词：VGOS 双线极化 条纹拟合 信噪比 时延观测量 相位弥散 

分 类 号：P228[天文地球—大地测量学与测量工程] P164[天文地球—测绘科学与技术]