Assessment of Pseudorange Measurements of Galileo FOC Satellites with Incorrect Highly Eccentric Orbits

On 22 August 2014 two Galileo satellites were launched in wrong orbit. In November 2014 European space agency started a salvaged mission to make these two satellites usable. On 5 August 2016 satellites started broadcasting ephemerides in navigation message for testing purposes. After this mission, the European Space Agency on October 8, 2016 requested to provide feedback on usage of these satellites. The objective of this work is the evaluation of the accuracy of the pseudorange measurements of these two satellites and its comparison with that of the other Galileo satellites. The reference term used to evaluate the accuracy of the pseudo-range measurements was obtained using precise orbits produced by IGS. The analysis has been carried on 20 days of data at 1 Hz collected by YEL2 IGS station. The results achieved show that the pseudoranges obtained from both the satellite 18 and the satellite 14 have an accuracy comparable to those obtained from the other satellites of the constellation. In detail, the satellite 14 has a mean error of about 13 cm, absolutely comparable with the mean error of the other satellites while the satellite 18 has the smallest mean error of about 1 cm. With regard to the standard deviation and the RMS the satellite 14 shows slightly higher values (about 1.06 meters) than the other satellites while the satellite 18 exhibits a value of about 80 cm exactly in line with that shown by the other satellites. The analysis shows that the measurements accuracy of the satellites on eccentric orbits are in the same range of the other satellites on nominal orbits, hence they can be potentially used in hostile environments such as urban canyon or obstructed area, where the satellites availability is crucial.