Precise point positioning (PPP) is famous for its capability of high-precision positioning with just one station as long as the receiver can receive global navigation satellite system (GNSS) signals. With the rapid development of BDS and Galileo, the number of available satellites for positioning has increased significantly. In addition, GPS III, GLONASS-K, BDS, and Galileo satellites can transmit triple-frequency signals. The potentials of multi-constellation GNSS PPP requires further analysis on a global scale. Therefore, we selected 96 multi-GNSS experiment (MGEX) stations with a global distribution and used 1 week’s data to assess the PPP performance. The results show that the PPP based on multi-frequency raw observations with spatial and temporal constraints has better performance than PPP using dual-frequency ionospheric-free observations. The main contribution of multi-constellation GNSS PPP is to shorten the convergence time. The convergence time for GPS PPP is approximately 40 min, which can be shortened to less than 20 min in multi-GNSS PPP. After convergence, the positioning accuracy of multi-GNSS PPP is improved by 0.5 to 1.0 cm compared with GPS or GLONASS PPP. The positioning accuracy of multi-GNSS could be further improved in the future with the BDS and Galileo precise products of orbits, clock and phase center offset/variation.

中文翻译：

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多星座GNSS精确点定位，结合多频原始观测和无电离层线性组合的双频观测

只要接收器可以接收全球导航卫星系统（GNSS）信号，精确点定位（PPP）便能以仅一个站的高精度定位而闻名。随着BDS和Galileo的飞速发展，可用于定位的卫星数量已大大增加。此外，GPS III，GLONASS-K，BDS和Galileo卫星可以发射三频信号。多星座GNSS PPP的潜力需要在全球范围内进行进一步分析。因此，我们选择了96个全球分布的多GNSS实验（MGEX）站点，并使用1周的数据来评估PPP性能。结果表明，与具有双频无电离层观测的PPP相比，基于具有时空约束的多频原始观测的PPP具有更好的性能。多星座GNSS PPP的主要贡献是缩短了收敛时间。GPS PPP的收敛时间约为40分钟，在多GNSS PPP中可以缩短到少于20分钟。收敛后，与GPS或GLONASS PPP相比，多GNSS PPP的定位精度提高了0.5至1.0 cm。利用BDS和Galileo精确的轨道，时钟和相位中心偏移/变化的乘积，将来可以进一步提高多GNSS的定位精度。