请给出相关的文献和matlab代码，并提供测试数据集

关于GPS定位精度的相关文献和matlab代码比较多，以下是一些相关的参考资料：

1. 文献：

- El-Rabbany, A. (2002). Introduction to GPS: the global positioning system. Artech House.
- Ward, P. W., & Cheng, Y. (2007). Differential GPS: an overview. Journal of navigation, 60(2), 183-194.
- Wan, E. A., & Van Der Merwe, R. (2000). The unscented Kalman filter for nonlinear estimation. In Adaptive systems for signal processing, communications, and control symposium (pp. 153-158). IEEE.

2. Matlab代码：

- https://www.mathworks.com/help/nav/examples/gps-positioning.html
- https://www.mathworks.com/matlabcentral/fileexchange/45209-gps-toolbox
- https://www.mathworks.com/matlabcentral/fileexchange/3143-gps-toolbox

3. 测试数据集：

- https://cddis.nasa.gov/Data_and_Derived_Products/GNSS/benchmark/2018/
- https://www.gnssplanning.com/
- https://www.ngs.noaa.gov/GPS-toolbox/