Abstract:

[Objective] Network-RTK is still one of the most important approaches to achieving real-time dynamic high precision positioning. The key to the technology lies in correctly fixing the integer ambiguity between reference stations and solving spatial correlation errors. [Methods] The direct estimation of atmospheric delay method (DEADM) was used in this paper: Kalman filter is chosen to directly estimate single difference ambiguity, single difference ionospheric delay, and tropospheric delay data, aiming at reducing the influence of noise and other residual errors when calculating atmospheric delay by geometry-free combination. [Results] Real-time stream data were used to verify the correctness of the above algorithm and different ionospheric delay extraction strategies were compared. [Conclusions] The results show that the variation of ionospheric delay extracted by using the direct estimation of atmospheric delay method is relatively more stable, more consistent with the short-term variation characteristics of ionospheric delay, and the calculation effect is little affected by satellite elevation. Users can quickly realize real-time centimeter-level positioning with good applicability.

Key words: Real-time, Network-RTK, Integer Ambiguity, Ionospheric Delay, Tropospheric delay