Realization and Evaluation of Real-Time Uncombined GPS/Galileo/BDS PPP-RTK in the Offshore Area of China's Bohai Sea

The real-time kinematic (RTK) technology has been widely used as the high-precision positioning method in the offshore area. However, RTK requires a bi-directional communication and groups measurement errors together, thereby limiting its mass-market applications. Combining the advantages of precise point positioning (PPP) and RTK, PPP-RTK has become one of the hotspot technologies in the mass market. In this contribution, we propose the uncombined multi-GNSS PPP-RTK model using uncalibrated phase delays (UPDs) estimated from the legacy ionosphere-free and Melbourne-Wubbena combination. With the UPDs estimated based on 14 regional stations, we conduct PPP ambiguity resolution (AR) at 3 augmentation stations and derive precise atmospheric corrections, i.e., RMS of zenith tropospheric and slant ionospheric correction can be up to 4.89 mm and 2.20 cm, respectively. After applying atmospheric correction, the correct fixed solution of four on-board kinematic experiments can be better than 95% and the positioning accuracy can be better than 5 cm in both horizontal and vertical direction, showing the encouraging performance similar to RTK in the offshore area.

Automated summary

Real-time kinematic (RTK) technology is widely used for high-precision positioning in the offshore area. However, its mass-market applications are limited due to the need for bi-directional communication and error grouping. PPP-RTK, combining precise point positioning (PPP) and RTK, has become a hotspot technology in the mass market. In this contribution, an uncombined multi-GNSS PPP-RTK model is proposed, using uncalibrated phase delays estimated from legacy ionosphere-free and Melbourne-Wubbena combination. By conducting PPP ambiguity resolution (AR) and deriving precise atmospheric corrections, the positioning accuracy in the offshore area can be improved to a level similar to RTK.