In-The-Field Trials for Real-Time Precise Positioning and Integrity in Advanced Applications

Precise Point Positioning (PPP) is a relatively new high precision positioning technique providing centimetre-level error. PPP processes dual-frequency pseudorange and carrier-phase measurements from a single user receiver, using detailed physical models and precise GNSS orbit & clock products calculated beforehand. PPP is different from other precise-positioning approaches like RTK in the sense that no reference stations are needed for obtaining the positioning solution. Another advantage of PPP is that since the GNSS orbit & clock products are global, the PPP solutions are global as well. PPP can be applied at post-processing level and also in real-time applications, provided that real-time input orbit and clock data are available. This paper is aimed at laying down a general integrity/reliability concept for the PPP solutions, following a practical service oriented approximation. The system is now being evaluated under several field scenarios simulating real operations, including static and kinematic use cases, different visibility conditions (open sky and occultation with different types of obstacles such as trees or buildings), and communication losses of different durations. We are going to perform accuracy versus integrity/reliability analyses, in order to detect cases in which the PPP solution exceeds the expected accuracy bounds and will try to correlate them with indicators either at system or at user levels which can be considered to be significant from the point of view of the integrity/reliability. PPP accuracy performances are about 5 to 10 centimeters after a 15 to 30 minutes convergence period, and our target is being able to ensure protection levels in the 0.5 to 1 meters range. With these activities we intend to lay down the foundations for an upper-level PPP applicable integrity/reliability concept to be refined in subsequent steps, but always closely linked to the final multimodal user perspective.