Swarm卫星星载接收机GPS信号中断统计特征分析  

Distribution of the GPS signal interruption for the spacebore receiver on board Swarm satellites

作　　者：胡洋 熊超[1,2] 尹凡 万欣[3,4] 郑宇豪 黄宇阳 刘裔文 朱艺洵 王丰珏 HU Yang;XIONG Chao;YIN Fan;WAN Xin;ZHENG YuHao;HUANG YuYang;LIU YiWen;ZHU YiXun;WANG FengJue(School of Electronic Information,Wuhan University,Wuhan 430072,China;Hubei Luojia Laboratory,Wuhan 430079,China;School of Atmospheric Sciences,Sun Yat-sen University,Zhuhai Guangdong 519082,China;Key Laboratory of Tropical Atmosphere-Ocean System,Sun Yat-sen University,Ministry of Education,Zhuhai Guangdong 519082,China;Shangrao Normal University,Shangrao Jiangxi 334001,China)

机构地区：[1]武汉大学电子信息学院,武汉430072 [2]湖北珞珈实验室,武汉430079 [3]中山大学大气科学学院,广东珠海519082 [4]中山大学热带大气海洋系统科学教育部重点实验室,广东珠海519082 [5]上饶师范学院,江西上饶334001

出　　处：《地球物理学报》2023年第11期4464-4477,共14页Chinese Journal of Geophysics

基　　金：国家自然科学基金(42174191)资助。

摘　　要：本文聚焦于欧空局Swarm卫星星载接收机在中纬地区出现的GPS信号中断事件,利用其近9年(2014年1月至2022年9月)的观测数据,详细统计了GPS信号中断事件发生的时空分布特征及与背景等离子体密度起伏的关系.研究结果表明Swarm卫星在其接收机锁相环带宽从0.75 Hz调整至1.0 Hz前后,GPS信号中断事件表现出不同的时空分布特征.在前一个时期,2014年1月1日至2016年8月11日,GPS信号中断事件主要分布在低纬磁赤道附近和高纬极区附近,少量中断事件分布在中国东部地区;而在后一个时期,2016年8月12日至2022年9月30日,GPS信号中断事件则出现在了所有的纬度,同时表现出显著的经度差异.前一个时期内GPS信号中断事件表现出了明显的季节依赖,而后一个时期内出现的GPS信号中断事件则出现了无季节特性的弥散状分布.该结果表明当Swarm星载接收机锁相环带宽调整至1.0 Hz时,虽然提升了其应对电离层闪烁条件下多普勒频移的动态调整范围,但同时也增加了接收机载波相位观测的热噪声,进而导致接收机产生了一些随机的短时信号中断.除了上述不同,两个时期内的GPS信号中断事件也表现出了一些共同特征,比如信号中断事件主要均集中在GPS卫星相对于Swarm处于较低仰角(<20°)的情况下;同时这些事件主要发生在发射较早的BlockⅡR和BlockⅡA类型GPS卫星上,暗示了随着发射年限的增加与星载设备的老化,GPS卫星的稳定性会逐渐降低.通过进一步对比分析Swarm卫星出现与未出现GPS信号中断轨道对应的原位电子密度观测数据,发现GPS信号中断的轨道其对应的电子密度波动更剧烈,表明背景等离子体密度的梯度强度是引起Swarm星载接收机在中纬地区出现GPS信号中断的重要原因.本文的研究结果对于星载接收机的设计优化,特别是提升其在电离层闪烁条件下的稳定性有重要的参考意义.This paper focuses on the Global Positioning System(GPS)signal interruption at middle latitudes for the spaceborne receiver on board the ESA's Swarm satellites.Using nearly 9 years data from 2014 January to 2022 September,the spatiotemporal distributions of these GPS signal interruption events as well as their relation with the fluctuation of ionospheric plasma density along Swarm orbits have been investigated.Taking Swarm C as example,we found that the GPS signal interruptions show totally different spatiotemporal characteristics before and after the phase-locked-loop(PLL)bandwidth of Swarm receiver changed from 0.75 Hz to 1.0 Hz.During the first period from 1 January 2014 to 11 August 2016,GPS signal interruptions are found mainly located in the vicinity of low(forming two bands along the magnetic equator)and polar latitudes,indicating the ionospheric sources for causing such GPS signal interruptions as reported by Xiong et al.(2018).However,during the latter period from 11 August 2016 to 30 September 2022,the GPS signal interruptions occur randomly at all latitudes,but show prominent dependence on the longitude.In addition,the GPS signal interruption events exhibit obvious seasonal distributions during the first period,rather than the second period.The different distribution of GPS signals during two period is associated with the enlarge of PLL bandwidth of Swarm receiver from 0.75 Hz to 1.0 Hz,which promotes the PLL dynamic range,and increase also the thermal noise of carrier phase,which further causes the random transient disruption of signals.Apart from the discrepancy mentioned above,there are also common features during the two periods.For instance,interruptions mainly accrue for the signal rays from GPS satellites to Swarm at low elevation angle(less than 20°).Moreover,interuptions are mostly observed for GPS satellites of types BlockⅡR and BlockⅡA,which were launched earlier than the other types.This result also suggests that the stability of GPS satellites becomes worse,with the increasing years a

关 键 词：Swarm卫星 星载GPS信号中断 接收机锁相环带宽 背景电子密度起伏 

分 类 号：P351[天文地球—空间物理学]