Modeling and assessment of regional atmospheric corrections based on undifferenced and uncombined PPP-RTK

doi:10.11947/j.AGCS.2020.20200103

Abstract

Abstract: High-precision atmospheric modification is an important prerequisite for accelerating the convergence of PPP-RTK. Based on regional tracking network stations, we first extract the slant ionospheric and zenith tropospheric delays based on the undifferential and uncombined PPP model. Then the estimated ionospheric and zenith tropospheric delays are used as the source observations for regional PPP-RTK atmospheric modeling. The slant ionosphere correction model is based on the single difference among satellites, while troposphere correction is modeled as undifferential zenith model. Based on the proposed method, prototype PPP-RTK server and client software systems are developed, where regional server generates and broadcasts atmospheric models and the user client realizes PPP-RTK with fast convergence by receiving the broadcast parameters from the server. Experiments using CORS network in Shanghai, the results on the server end show that both ionospheric and tropospheric model of GPS, GALILEO, and BDS systems achieve an accuracy of few mm. The 646 sets of PPP-RTK experiments on the client side show that: ①For horizontal coordinates, 89.16% of all solutions converged in 30 s, 91.80% in 1 minute, and 95.98% in 2 minutes. ②For the three-dimensional positions, 86.22% converged in 30 s, 88.70% in 1 minute and 93.34% in 2 minutes. With the addition of atmospheric constraints, the fixed rate of ambiguity is 95.59%, and the localized RMSE in the horizontal and three-dimensional directions after convergence is 2.35 and 4.63 cm, respectively. The real-time PPP-RTK test experiment shows similar results, where time to first fix (TTFF) is 36 seconds,accuracy of horizontal and three-dimensional coordinates reach 1.13 and 3.21 cm, respectively.

Key words: undifferenced and uncombined PPP, PPP-RTK, regional atmospheric correction model, fast convergence

CLC Number:

P228

WU Guanbin, CHEN Junping, WU Xiaomeng, HU Jinlin. Modeling and assessment of regional atmospheric corrections based on undifferenced and uncombined PPP-RTK[J]. Acta Geodaetica et Cartographica Sinica, 2020, 49(11): 1407-1418.

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