Advanced RAIM Demonstration using Four Months of Ground Data

In the near future, many more navigation satellites with dual frequency L1 and L5 will be deployed. The increased number of satellites and the possibility of mitigating the ionospheric delay using dual frequency have opened the door to the possible use of RAIM for vertical guidance. For this purpose, several Advanced RAIM (ARAIM) algorithms have been proposed and extensive simulation studies have established that with two constellations it might be possible to achieve global coverage of LPV 200, which requires a 35 meter Vertical Alert Limit. However there have only been limited tests with actual receiver measurements. In order to build confidence in ARAIM for vertical guidance, which is dependent on the performance of the GNSS core constellations, an extensive validation effort on an ARAIM prototype will be necessary. In this paper, we will test an ARAIM prototype using large datasets of L1 CA and L2 semi-codeless GPS measurements collected in ground stations located worldwide. Our specific goal for this paper is to test the ARAIM algorithm on a hundred ground receivers for four months. For each receiver, we will compute the Vertical Protection Level (VPL), the actual Vertical Position Error (VPE) etc every second. Then we will test the ability of ARAIM to bound VPEs under nominal conditions – the actual data , data fault conditions – the faults that might have happened during the four months and are similar to the real fault condition-, and simulated fault conditions.