Evaluation of High-Precision, Single-Frequency GPS Point Positioning Models

In this paper we evaluate the performance of singlefrequency, single-point positioning processors with an emphasis on ionospheric delay handling. A number of least-squares processors with singlefrequency code-only and code-and-carrier-phase observables were developed. Processing model hierarchy is based on measurement error handling, starting with a basic code-based navigation solution and progressing to the code-and-carrier-phase model. Measurement error handling includes receiver clock error reduction by the between-satellite differencing process, various ionospheric delay models and a tropospheric delay prediction model. Ionosphere-free results are compared against values from global ionospheric delay maps. Our current point positioning processors achieve few dm-level accuracy.