Preliminary Study of Improving Position in North of Algeria Using GPS and EGNOS Corrections

Abstract

The European Geostationary Navigation Overlay Service (EGNOS) offers an augmentation signal to the Global Positioning System (GPS). Presently, EGNOS augments GPS performance using the L1 (1575.42 MHz) by providing correction data and integrity information for improving positioning and navigation services over Europe. The corrections transmitted by EGNOS contribute to reduce error sources related to satellite clocks, satellite position and ionospheric effects. Others errors sources (tropospheric effects, multipath and user receiver contributions) are local effects those cannot be corrected by this system. This research presents the preliminary analysis to investigate the improvement positioning of the EGNOS system in North of Algeria without RIMS station, this area until considered as covered by EGNOS. The raw GPS data were collected by a geodetic receiver (Trimble Net R9), which was installed at four sites in different date of the year 2018, and over a time interval from 6 to 24 hours. Analysis of the parameters characterizing the accuracy of positioning was performed in two calculation modes; firstly, with measurement data of GPS only in mode SPP (single positioning point) and secondly, with differential correction of EGNOS in mode SBAS. The characterization of the receiver's position error using the horizontal and vertical position error (HPE and VPE) is obtained from the position error in three dimensions (X, Y and Z). The errors are computed based on the difference between measured positions and the precise positions. The results reveal that the use of EGNOS correction improves the positioning accuracy in comparison with the standalone GPS point positioning. Further, results show that there is an improvement in the three dimensional positioning accuracy. It is also shown that the use of full EGNOS correction demonstrated horizontal and vertical positioning are better than 2 meters and better than 6 meters (95%), respectively. While in GPS only, it is around 4 meters in horizontal and 8 meters in vertical.