广播星历SSR改正的实时精密单点定位及精度分析

Realization and analysis of real-time precise point positioning based on SSR broadcast ephemeris corrections

本文分析了利用广播星历和SSR改正信息获取实时精密星历和卫星钟差的方法,并对生成的实时产品进行了精度评估:利用IGS分析中心提供的实时NTRIP数据流SSR改正信息,基于广播星历改正RTPPP模型实现了实时静态和动态精密单点定位,并分别进行了精度分析。结果表明:将广播星历SSR改正获得的实时产品与IGS最终产品相比较,卫星轨道互差RMS值为4cm^7cm、卫星钟差互差RMS值优于0.3ns;实时静态PPP在观测时段6h以上的情况下,可实现水平方向2cm、高程方向4cm的定位精度,24h单天解的平面及高程方向精度均优于2cm;实时动态PPP的定位精度可达cm级,收敛至亚dm级精度的时间与事后PPP在不固定非差模糊度情况下所需的时间相当。

The acquisition approach of real-time precise satellite orbit and clock products based on State Space Representation （SSR） corrections to broadcast ephemeris was analyzed in the paper. The gen- erated real-time satellite orbit and clock Products were further evaluated. Based on the Real-time Precise Point Positioning （RTPPP） model with broadcast ephemeris corrections, real-time static and kinematic PPP were realized using real-time SSR corrections through NTRI Pstreams disseminated by IGS analysis centers first, and then the accuracies of real-time static and kinematic PPP were also evaluated. Experi- mental results showed that the RMS of differences between real-time products and IGS final products could be about 4cm- 7cm for satellite orbits and better than 0.3ns for satellite clocks. The accuracy of static RTPPP could reach 2cm level in the horizontal component and 4cm level in the up component when the Ob- servation session length is more than 6 hours. The accuracy of 24-hour daily solution of static RTPPP could be better than 2cm in the horizontal and vertical components. The accuracy of kinematic RTPPP could reach centimeter level. Its convergence time to sub-decimeter could be almost the same as that taken by post-processing PPP with ambiguity unfixed.