Satellite Navigation Users Group

After its successful launch on 27 April, GIOVE-B began transmitting navigation signals on 7 May. For the first time, the GPS-Galileo common signal is being transmitted - using the multiplexed binary offset carrier (MBOC) agreed in July 2007 for GPS III and Galileo.

It is claimed that these signals, controlled by another first in space - a passive hydrogen maser atomic clock - will provide higher accuracy where multipath and interference are present, and deeper penetration for indoor navigation.

It will also demonstrate that Galileo and GPS 'are truly compatible and interoperable and that positioning services will benefit all users worldwide'.

GIOVE-B is orbiting at the proposed Galileo constellation height of 23,173 km - orbiting in 14 h 3 m.

Several facilities are involved in the validation process, including the Control Centre at Fucino (Italy), the Galileo Processing Centre at ESTEC (Netherlands), the ESA ground station at Redu (Belgium) and Rutherford Appleton Laboratory's Chilbolton Observatory (UK).

Checks to be undertaken include:

• Transmission format of nav signals on 3 frequencies
• Transmitted signal powers, centre frequencies and bandwidths
• Effect of the environment at orbit height
• Effect of the propagation path from space to ground

Details from ESA