GALILEO – Europe’s answer to GPS and GLONASS has passed a historic milestone this week; The very first determination of a ground location using only Galileo satellites currently in orbit is now done.
This first position fix of longitude, latitude and height took place at the Navigation Laboratory at European Space Agency’s technical heart ESTEC, in Noordwijk, the Netherlands on the morning of 12 March, 2013. The position fix had an accuracy between 10 and 15 metres which is quite decent and much along expected lines taking into account the limited infrastructure and other limitations.
This milestone is a fundamental step that confirms the Galileo system is working as planned. Fixing the location of any receiver on ground requires a minimum of four satellites – in order to solve for the 4 unknowns i.e. Latitude, Longitude, Height and Time (the time is not synced between the receiver clock and satellite clock). The first two Galileo satellites were launched in October 2011, with two more added during 2012.
These four satellites were used to determine the ground location at Noordwijik, Netherlands. The location fix was the subsequent step following the testing of the satellites and the navigation messages. Navigation message send from the satellite include information regarding the satellites’ position in space expressed in Keplerian orbital parameters which are used by the receiver to calculate the distance between the satellite and it’s position which when coupled with range information from 3 more satellites helps locate the receivers’ position.
“The test of today has a dual significance: historical and technical,” Javier Benedicto, ESA’s Galileo Project Manager.