A Network RTK Method for Large-Scale Satellite Navigation and Positioning Reference Stations

  Objectives  Network real-time kinematic (RTK) technology can provide real-time and high-precision positioning service for users over the wide range, however, the current technology depends on high density of satellite navigation and positioning (SNAP) reference station network. To satisfy the high-precision positioning requirements based on the sparse reference station network, this paper recommends a network RTK service method based on virtual atmosphere constrait(VAC).

  Methods  Firstly, a non-combined double-difference observation model is constructed to solve and fix the network RTK baseline ambiguity quickly. Then, the baseline atmospheric delay is extracted and the slant path ionosphere and zenith tropsphere are established respectively. Finally, the interpolated atmospheric delay and its accuracy information are regarded as virtual observations to improve the positioning performance of the terminal RTK. Based on a 205.1 km station spacing SNAP network from a northwest region, China, six rover stations inside and outside the network are used for termininal RTK verification.

  Results  The results show that the VAC network RTK service method can meet the needs of high-precision positioning users over large-scale reference networks. The terminal positioning accuracy and initialization speed by the VAC method are significantly improved by 61.64% and 9.96% compared with the traditional virtual reference station method. In this service mode, the average horizontal and vertical root mean squares of the fixed solution for the six terminals are 1.19 cm and 2.73 cm. Initializing RTK solution by a lot of times, 88.78% of periods can be fixed within 2 epochs for the six rover staions.

  Conclusions  The VAC service mode has good adaptability to both users inside and outside the large-scale SNAP base station network.