Accuracy and Integrity are important indexes in satellite navigation for aviation. Currently, the Satellite Based Augmentation Systems (SBASs) are all designed for single GPS constellation. With the development of Compass, there will be dual constellation in the sky, then how to get better navigation accuracy and integrity in SBASs for GPS and Compass constellations is of significance. As the largest error source, ionospheric delay, its existing correction methods were just for GPS constellation and over conservative. In this paper, we propose a new method to make more accurate ionospheric delay correction and tighter error bound orienting towards GPS and Compass dual constellations. Firstly, as the basis of ionospheric delay modeling, we make a spacial correlation analysis of ionospheric delay on ionospheric pierce points (IPPs). Then, considering that some IPPs formed by Compass are motionless, we make a filtering process to estimate the ionospheric delays at ionospheric grid points (IGPs) to better reflect the ionospheric temporal variation. Finally, we conduct a simulation on ionospheric delay estimation at IGPs in dual constellations through planar fit method and filtering method. It can be concluded that the filtering method can bound the ionospheric delay correction error more tightly, simultaneously the ionospheric delay correction accuracy is not only decreased but also improved a bit.
展开▼
