Galileo Interoperable with GPS

ESA’s first two Galileo navigation satellites in space have achieved their latest milestone, transmitting dummy signals in a modulation scheme designed to allow full interoperability with the US GPS once operational services start. An advanced modulation technique offers robust protection against signal interference and the misleading signal reflections known as ‘multipath’.

The first two Galileo satellites were launched from Europe’s Spaceport in French Guiana into medium orbits on 21 October 2011, and since then have been progressively put through their paces in a series of tests.

These satellites are serving to validate the Galileo system design as well as being fully functional elements of the full 30-strong constellation that will follow.

Four satellites, the minimum number needed to achieve a position fix at user level, will become available later on this year. This autumn the next two satellites will be launched together from French Guiana.

Once they are commissioned, Galileo will have its operational nucleus complete, able to perform actual ranging when all four satellites are visible from a receiver.