The European Space Agency's GIOVE-B satellite began transmitting navigation signals successfully today.

GIOVE-B is transmitting the GPS-Galileo common signal using a specific optimised waveform (multiplexed binary offset carrier) in an event described by the ESA as "a truly historic step for satellite navigation".

Transmissions are in accordance with the agreement drawn up in July 2007 by the EU and the US for their respective Galileo and GPS III systems.

The signals will provide higher accuracy in challenging environments where multi-path and interference are present, and deeper penetration for indoor navigation.

"With GIOVE-B broadcasting its highly accurate signal in space we have a true representation of how Galileo can provide advanced satellite positioning services while ensuring compatibility and interoperability with GPS," said Galileo project manager Javier Benedicto.

GIOVE-B's navigation payload was switched on and signal transmission commenced on 7 May and the quality of these signals is now being checked.

Several facilities are involved in this process, including the GIOVE-B Control Centre at Telespazio's facilities in Fucino, Italy; the Galileo Processing Centre at ESA's European Space Research and Technology Centre in the Netherlands; the ESA ground station at Redu, Belgium; and the Rutherford Appleton Laboratory Chilbolton Observatory in the UK.

ESA said that the quality of the signals transmitted by GIOVE-B will have an important influence on the accuracy of the positioning information provided by receivers on the ground.

GIOVE-B carries a passive hydrogen maser atomic clock, which is touted as being able to deliver "unprecedented stability performance".