GNSS Satellite (GIOVE-A)


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Monday, 12 May 2008

GIOVE-B is transmitting

After its successful launch on 27 April, GIOVE-B has began transmitting navigation signals on May 7. This is a truly historic step for satellite navigation since GIOVE-B is now, for the first time, transmitting the GPS-Galileo common signal using a specific optimised waveform, MBOC (multiplexed binary offset carrier), in accordance with the agreement drawn up in July 2007 by the EU and the US for their respective systems, Galileo and the future GPS III. These GIOVE-B signals, locked on-board to its highly stable Passive Hydrogen Maser clock, will provide higher accuracy in challenging environments where multipath and interference are present, and deeper penetration for indoor navigation. It demonstrates that Galileo and GPS are truly compatible and interoperable and that positioning services will benefit all users worldwide.

With GIOVE-B broadcasting its highly accurate signal in space using is extremely stable clock we have a true representation of what Galileo will offer to provide the most advanced satellite positioning services, while ensuring compatibility and interoperability with GPS. I am looking forward to the first microwave obeservations (in the RINEX format) from the 13 world wide distributed Galileo Experimental Sensor Stations (GESS) to study the quality of the signals in comparison with GPS and GIOVE-A. In addition this should give us information regarding the stability and behaviour of the on-board clock.

As soon as I have some results I will inform you here (after ESA approval of course).

For more information look here:

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Sunday, 27 April 2008

Giove-B a major step forwards for Galileo

Today, 27-April-2008, Giove-B was launched succesfully!

You can watch the launch at:

The Giove-B satellite, which weight is only 500 kg, was lofted into a medium altitude orbit around the earth by a Soyuz/Fregat rocket departing from the Baikonur cosmodrome in Kazakhstan by launch operator Starsem. Lift-off occurred at 04:16 local time on 27 April (00:16 Central European Summer Time). The Fregat upper stage performed a series of manoeuvres to reach a circular orbit at an altitude of about 23,200 km, inclined at 56 degrees to the Equator, before safely delivering the satellite into orbit some 3 hours and 45 minutes later. The two solar panels that generate electricity to power the spacecraft deployed correctly and were fully operational by 05:28 CEST.

Giove-B will continue the demonstration of critical technologies for the navigation payload of the future operational Galileo satellites. Like Giove-A, Giove-B carries two redundant small-size rubidium atomic clocks, each with a stability of 10 nanoseconds per day. But it also features an even more accurate payload: the Passive Hydrogen Maser (PHM), with stability better than 1 nanosecond per day. The first of its kind ever to be launched into space, this is now the most stable clock operating in earth orbit.

GIOVE-B also incorporates a radiation-monitoring payload to characterise the space environment at the altitude of the Galileo constellation, as well as a laser retroreflector for high-accuracy laser ranging. Signal generation units will provide representative Galileo signals on three separate frequencies broadcast via an L-band phase array antenna designed to entirely cover the visible earth below the satellite. The satellite is now under the control of Telespazio's spacecraft operations centre in Fucino, Italy, and in-orbit checking-out of the satellite has begun.

The next step in the Galileo programme will be the launch of the first four operational satellites, to validate the basic Galileo space and related ground segment, by 2010. Once that In-Orbit Validation (IOV) phase is completed, the remaining satellites will be launched and deployed to reach the Full Operational Capability (FOC), a constellation of 30 identical satellites.

Galileo will be Europe's very own global navigation satellite system, providing a highly accurate, guaranteed global positioning service under civil control. It will be interoperable with the US Global Positioning System (GPS) and Russia's GLONASS, the two other global satellite navigation systems. Galileo will deliver real-time positioning accuracy down to the metre range with unrivalled integrity. Numerous applications are planned for Galileo, including positioning and derived value-added services for transport by road, rail, air and sea, fisheries and agriculture, oil-prospecting, civil protection, building, public works and telecommunications.

I am looking forward to the first real observations from Giove-B and to compute its first accurate orbit and especially accurate clock corrections. The passive hydrogen maser is the real "special" that Giove-B offers. Accurate clocks in space may offer a substantial benefit in all areas of GNSS. For the work I do, high precission GNSS at the mm level, I hope that the accurate Galileo clocks will offer an accuracy improvement of a factor of at least two, maybe more....

As soon as I have some first results I will post a new Blog here.

For more general info on Giove-B and Galileo have a look at:

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