摘要
对导航卫星历书问题进行了综合研究,并结合J_2项分析解,提出了两套新的历书参数拟合方法和用户算法,与正常算法不同的是:8参数历书拟合算法以(?)=-3/2J_2等(R_e^2)/(p^2)n cos i隐性直接代替历书参数Ω_1;在用户算法中对MEO卫星以ω_k=ω_0-ω_1·(Δt/2-t_k),对高轨卫星以ω_k=ω_0-ω_1·(Δt/2-t_k)/2修正历书参数ω_k,其中ω_1=(A_2)/(p^2)n(2-5/2sin^2 i).9参数历书拟合算法在8参数的基础上增加了一个历书参数(?)=(T_Err_n-T_Err_0)/Δt/α参数,在用户算法中以ω_k=ω_0-ω_1·(Δt/2-t_k),M_k=M_0+n·t_k-(?)·(Δt/2-t_k)修正ω_k和M_k.通过多组模拟轨道和IGS精密轨道的历书拟合实验,结果表明,新8参数历书拟合方法具有参数少、迭代收敛速度快、对MEO卫星拟合精度高等优点;新9参数历书拟合算法,迭代收敛快,拟合精度优于其他算法.
Based on the 1^(st)order perturbation analytic solution theory of satel- lite,the two improved almanac parameters fitting algorithm of navigation satellites and their user calculation arithmetic,so called the'8 parameters'and the'9 parameters'algorithm,are introduced in this article.For the'8 parameters'arithmetic,only with'Week.T_(oa),a^(1/2),e,i,Ω_0,ω_0,M_0',less parameters than the normal algorithm are needed to express the new almanac information.According the broadcasted new almanac pa- rameter'a^(1/2),e,i',the user may calculate'(?)、ω_1'by the following formulas directly: (?)=-3/2J_1(R_e^2)/(p^2)n cos i,ω_1=3/2(R_e^2)/(p^2)n(2-5/2sin^2i). And more,the user may get more precise satellite position by correcting theω_k at any epoch byω_k=ω_0-ω_1·(Δt/2-t_k)for MEO,ω_k=ω_0-ω_1·(Δt/2-t_k)/2 for IGSO/ GEO. Based the'8 parameters'algorithm,the'9 parameters'algorithm is also different from the normal parameters,with'(?)'replaced by'(?)'.(?)can be calculated by(?)= (T_Err_n-T_Err_0)/Δt/a.T_Err_n,T_Err_0 are the fitting errors in transversal direction at the last epoch and the first epoch respectively,Δt means the fitting time span in seconds.The rest almanac parameters Week.T_(oa)、a^(1/2)、e、i、Ω_0、ω_0、M_0 can be fitted by the former'8 parameters'algorithm.The user should correct theω_k、M_k,accordingω_1、(?) at any epoch byω_k=ω_0-ω_1·(Δt/2-t_k),M_k=M_0+n·t_k-M·(Δt/2-t_k). With the two new algorithm,many almanac fitting examples on some simulated satellite orbits or IGS GPS precise orbits are shown,which lead to the following conclu- sion:Less parameters are needed to fitting the so called 8 parameters almanac,while, the new algorithm can lead to higher accuracy for MEOs,quicker convergence through iterative calculation.The same is true for the so called 9 parameters almanac fitting arithmetic,which can lead to much higher accuracy than any other almanac fitting algo- rithm.
出处
《天文学报》
CSCD
北大核心
2008年第3期288-296,共9页
Acta Astronomica Sinica
基金
教育部重点实验室开放研究基地(06-07)资助项目
关键词
天体测量学和天体力学
历书
方法
数值
Astrometryand Celestial Mechanics
Ephemerides,Methods
numerical
