Standalone real-time navigation algorithm for single-frequency ionosphere-free positioning based on dynamic ambiguities (DARTS-SF)

INTRO
GPS receiver design has stabilized over the last years resulting in decimeter-level noise for pseudoranges and sub-millimeter noise for carrier phases. However, standalone users still face the constraints imposed by the systematic errors of GPS. Errors of broadcast orbits and clocks, unmodelled tropospheric delays, and multipath errors limit the real-time standalone positional accuracy. The system biases of GPS (errors of
broadcast orbits and clocks) are generally considered to be a primary limitation for the further improvement of standalone positioning accuracy. This paper presents original algorithms intended to push the accuracy of standalone positioning beyond this limitation and bring it close to typical accuracy of DGPS. These algorithms effectively suppress short-term multipath noise and compensate for the system biases. As a result, the positional accuracy is reduced to almost sub-meter level. In the future, with the advent of Galileo, these algorithms will help to achieve actual decimeter-level positional accuracy for standalone receivers.

Two original algorithms are presented in this paper:
1. Phase-aided positioning method, which uses dynamic phase ambiguities. The acronym of the method is DARTS (Dynamic Ambiguities Real-Time Standalone). This method is based on the ability of floating ambiguities to absorb long-term errors. DARTS is designed to compensate for system biases and bring the accuracy of positioning to the values typical for DGPS.

2. Doppler-aided velocity/position algorithm provides a direct way to compute precise velocities. It also improves the quality of positioning by using Dopplercomputed accurate velocities. Doppler-aided positioning is particularly effective in dynamic limited visibility conditions, such as in urban driving.

FULL technical paper (PDF):