First Joint GPS/IOV-PFM Galileo PVT estimation using carrier phase measurements

The advent of the first two satellites of the final Galileo constellation launched by Soyuz from Europe’s spaceport in French Guiana on October 21st is a major milestone for the European as well as global satellite navigation field. In fact, these two satellites pave the way for a much awaited set of experiments testing the benefits brought about by an additional constellation in orbit, Galileo. The European constellation formed by last generation satellites carrying very precise hydrogen maser clocks, and transmitting sophisticated navigation payloads, is expected to increase positioning availability and improve satellite geometry so far as to decrease positioning errors with respect to the use of GPS satellites exclusively. In this paper, signal acquisition, tracking and demodulation of the signal broadcast by the first Galileo satellite (the so-called IOV-PFM Galileo satellite) in the E1 bandwidth is performed. Starting to monitor this satellite from December 2011, we were able to observe a valid ephemeris data on December 21 and December 22 in 2011, respectively. Thus, a valid satellite orbit information has been obtained and used to compute pseudoranges in the Galileo system. Furthermore, precise carrier-phase positioning is carried out combining GPS L1 with Galileo E1 carrier phase measurements to reach a cm level accuracy positioning. The joint GPS and Galileo PVT strategy is then compared to the standalone GPS PVT.