USB观测数据时标偏差影响分析与评估  

Analysis and Evaluation of Time Tag Bias of USB Measurements

作　　者：郑爱武[1,2] 周建平[1] 胡松杰[2] 孙靖[2,3] 

机构地区：[1]北京航空航天大学,北京100191 [2]北京航天飞行控制中心,北京100094 [3]上海天文台,上海200030

出　　处：《空间控制技术与应用》2011年第1期36-39,共4页Aerospace Control and Application

摘　　要：USB系统是目前中国载人航天和月球探测任务的主要测控网.由于USB测量设备本身以及无线电信号传播媒介以及其他误差因素的影响,USB测量数据中包含了各种误差,需要在定轨时对观测数据进行误差修正.通常,例行的USB测量误差修正包括对流层折射修正、电离层延迟修正和通道延迟修正,但对定轨过程中可能影响观测数据计算精度的时标偏差并未作修正.针对USB测距测速观测数据,详细研究了观测数据时标偏差对观测值计算精度的影响,分析了误差影响特性,建立了相应的误差修正模型,并通过与卫星星历偏差对USB测距测速观测值计算精度影响特征的比较,发现时标偏差对测量的影响与轨道沿迹误差对观测计算值的影响等效,这使得在定轨过程中分离时标偏差的难度较大.提出了基于星载GPS定位数据分离时标偏差的方法,并利用某次任务的实测数据,分离出了该次任务中USB测量的时标偏差.最后针对目前USB数据时标偏差影响和观测误差量级相当的情况,建议将目前的观测时标精度提高到优于0.1ms的水平,使得时标偏差的影响降低到比观测误差小一个量级的水平.The Unified S-band system（USB） is a main TTC（Telemetry,Tracking and Command） network used in manned space missions and lunar exploration programs of china.Because of the influence of propagation environment of radio signal,measure environment change in USB station,instrument error and other interference,it＇s inevitable to contain a great variety of error in USB measurements.Therefore,it＇s necessary to perform error correction before orbit determination.Usually,most error correction of USB measurements principally includes the refraction error of troposphere,ionospheric delay and channel delays.Other errors such as time tag bias of observations is omitted.The influence of time tag bias of the observations of USB range and range-rate on observation accuracy is studied in detail,the characteristics of the results are analyzed,and error correction model is formulated in this paper.Compared with the influence of spacecraft ephemeris bias on observation accuracy,it shows that the influence of time tag bias is equivalent to that of orbit error along-track,thus making it difficult to separate them apart.A method to separate the time tag bias based on real time positioning results of onboard GPS receiver is proposed in this paper.A sample is given by using the real measurements obtained in a mission to separate the time tag bias.In view of the fact that the influence of time tag bias is of the same order of magnitude as observation error,it is proposed that the recording accuracy of time tag should improve to 0.1ms to decrease the influence of time tag bias.

关 键 词：测距 测速 时标偏差 残差分析 

分 类 号：V4[航空宇航科学技术]