GPS/GLONASS组合精密单点定位研究

与模糊度为浮点解的精密单点定位（precise point positioning，PPP）相比，PPP模糊度固定技术具有更快的收敛速度和更好的定位精度。但当GPS卫星数目少或几何构形不好时，需要较长时间实现GPS PPP模糊度的首次固定，通过加入GLONASS卫星可以有效缩短首次固定时间。推导了基于整数相位钟法的GPS/GLONASS组合PPP模型并进行了大量实验解算。40组静态模拟动态实验表明，GPS PPP模糊度首次固定平均需要50.2 min，但在GLONASS辅助下只需25.7 min，减少了48.8%，而且定位精度也有提高。车载动态实验表明，由于受观测条件限制，GPS PPP模糊度难以固定，但在GLONASS辅助下仍能实现GPS PPP模糊度固定。

Study on Precise Point Positioning Based on Combined GPS and GLONASS

Compared to ambiguity-float precise point positioning (PPP), ambiguity-fixed PPP needs a short convergence time and has better positioning accuracy. However, when there are only a few GPS satellites without an optimal geometrical distribution, ambiguity-fixed PPP requires time to achieve a first fixed solution. The objective of our research was to reduce the time to first fixed solution (TFFS) for GPS-only PPP by adding GLONASS satellites. An observation model for GPS/GLONASS ambiguity-fixed PPP using the integer phase clock method was developed and tested. Forty kinematic tests using static data show that the average TFFS is 50.2 min for GPS ambiguity-fixed PPP while only 25.7 min for GPS/GLONASS ambiguity-fixed PPP; reduced by 48.8% after adding GLONASS observations. A vehicular test demonstrates that GPS-only PPP cannot get its first fixed solution due to a less than ideal observation environment while GPS/GLONASS PPP can realize ambiguity fixing.