Application research of GPS PPP in railway scene based on uncalibrated phase delay paramteters

The Global Navigation Satellite System (GNSS) reference stations along the railway in complex and dangerous areas are relatively sparse. How to obtain the high precision position information for the stations under this scenario is an important problem. Taking the single GPS system for instance, the satellite tracking number and the position dilution of precision (PDOP) are evaluation, the reliability and usability of the observation are carried out and the research of enhanced precise point positioning (PPP) technology is implemented by using 7 GNSS stations (14 observation periods) along the railway. The results show that: 1) the average numbers of tracking satellites is about 5.14 to 9.07 and the average PDOP is about 2.19 to 5.72 in all time periods, which has high localization availability; 2) Enhanced PPP can further improve the accuracy of PPP in railway environment. When the observation time is about 90 min, the positioning solution can be better than 10 cm and 15 cm in horizontal and vertical direction, respectively. Compared with float solution, the positioning accuracy in 3D direction can be improved by about 35.43%. This study can provide high-precision position information in the survey and construction stage for complex railway scene.