We may not always be aware of it, but the daily function of the technological world around us is extremely dependent on satellite navigations systems. It helps the DHL guy deliver those parts you were waiting for, and keeps the global financial and communication systems running with precision timing. So, when these systems have a bad day, they can spread misery across the globe. To keep an eye on these critical constellations, [Bert Hubert] and friends set up a global open source monitoring network that aims to track every satellite in the GPS, Galileo, BeiDou and GLONASS constellations.
Off-the-shelf GNSS receivers are used to feed navigation messages to a machine running Linux/OSX/OpenBSD. The messages are processed to calculate the position (ephemeris), extract atomic clock timings and status codes of each satellite. Publicly available orbital data is then used to make an informed guess regarding the identity of the satellite in question.
All this data enables [Bert] to determine ephemeris discontinuities, time offsets, and atomic clock jumps. The project’s twitter feed, @GalileoSats, is very active with interesting updates. Go check it out! All the collected data is available for research purposes and the software is up on Github.
Thanks for the tip [DarkSideDave]!