星载单频GPS数据的电离层延迟改正方法分析

利用C/A码单点定位对LEO(Low Earth Orbit)卫星上的电离层延迟改正方法——"电离层比例因子法"进行了分析研究.计算的CHAMP卫星的轨道结果表明:采用电子密度峰值高度(hmF2,F2 region maximum electron density height)平均值和瞬时值计算的电离层比例因子α变化范围分别为0.3~0.4和0.2~0.65之间,两者最大差异可达0.3,相比较而言,hmF2瞬时值的结果更加合理,并且相应的大地高H方向的系统偏差要降低0.05~0.3m左右;与双频无电离层组合的普通单点定位结果相比表明该方法能较好地消除电离层一阶项所引入的H方向上的系统偏差;该方法适用的LEO卫星轨道高度范围大致在200~ 600km之间,当轨道高度超过700km时,该方法并不适用.

Analysis on ionospheric delay correction method of space-borne single-frequency GPS data

With the technology of standard point positioning based on C/A code received by low earth orbit(LEO),one of the ionospheric delay correction method,the method of ionospheric scale factor,was discussed.The computed ionospheric scale factor α using the mean and instantaneous value of F2 region maximum electron density height is 0.3~0.4 and 0.2~0.65 respectively,and the maximum difference between them reaches to 0.3.Comparatively,the latter coincides with the reality better,and it reduces the systematic error in the geodetic height direction by 0.05~0.3 m.With the comparison to the standard point positioning based on ionosphere free combination of the dual-frequency code measurements,the method could eliminate the systematic error in geodetic height induced by the first order of ionospheric delay.And the method could adapt to the LEO altitudes of about 200~ 600 km,but it’s useless at the altitudes more than 700 km.