北斗系统简约历书的初步设计分析

Preliminary Design and Analysis of BDS Reduced Almanac

简要介绍了全球定位系统的简约历书参数,分析了简约历书与中等精度历书参数的不同之处。基于此初步设计出了我国北斗系统的简约历书参数,给出了相应的轨道长半轴参考值和常量参数取值。导出了卫星位置对简约历书参数的偏导数,分析了常量参数的变化对简约历书参数拟合精度的影响。计算结果表明:(1)轨道长半轴的较小偏差不会影响简约历书参数的精度;(2)升交点赤经变化率的较小波动对简约历书参数的精度影响不大;(3)轨道面倾角的微小变化将会引起较大的简约历书参数拟合误差;(4)北斗系统的简约历书参数精度与全球定位系统简约历书参数基本相当,这也说明了所设计的北斗系统简约历书参数是合理的。

In this paper, GPS reduced almanac parameters are introduced briefly, and the differences between reduced almanac and midi almanac are analyzed. On this basis, BDS reduced almanac parameters are designed preliminary, and correspond reference values and constant parameter values are given. Based on the reduced almanac user algorithm, partial deriva- tives of satellite position on reduced almanac parameters are obtained, and the effect of the change of constant parameters on the fitting precision of reduced almanac is analyzed. Calculated results show that.. （1）the accuracy of reduced parameters is not affected at all by small deviation of major semi-axis; （2）the small fluctuations of ascension rate have a little influence on the re duced almanac parameters; （3）the small change of the inclination of orbit plane will result in serious fitting error of reduced almanac parameters; （4）the precision of BDS reduced almanac is almost the same as the GPS reduced almanac parameters, which indicates that BDS reduced almanac parameters is designed reasonably.