Accuracy Study of a Single Frequency Receiver Using a Combined GPS/GALILEO Constellation

Kurzfassung

As the date of availability of GALILEO approaches, more and more interest appears to pre-evaluate the accuracy of GALILEO and combined GPS+ GALILEO receivers. The majority of simulations made are based on the general use of UERE (often presented as a function of the elevation angle of the satellite) multiplied by the GDOP (Geometric Dilution Of Precision) matrix. This is a too approximate approach to state for the real position error distributions. Therefore, the concept of an Instantaneous Pseudo Range Error (IPRE) is defined and is implemented into NAVSIM the DLR’s end to end GNSS simulator. This new module coupled with the other modules of the simulator permit to lead complete End-to-End simulations. This new functionality has the advantage to augment the field of applications and to couple the generation of errors already implemented in NAVSIM with error distributions coming from real measurements. This study is a good first approach to compare constellations between each other regarding the accuracy issue. The IPRE concept multiplies the functionalities thanks to its ability to generate real distributions of errors. The application to a combined existing constellation (GPS) for which real measurements can be used with a not yet existing constellation (GALILEO) for which only simulated data can be used is an interesting approach. These results can directly be used to test the impact of correction models, of filtering techniques, of antenna types to a combined GPS/GALILEO system thanks to the time series of IPRE and the instantaneous individual errors output from NAVSIM. The best strategy of error mitigation technique can be tested and the result can be used for receiver design before the launch of GALILEO system.