[amsat-bb] Gallileo GIOVE-A navigation signal available to users

Trevor m5aka at yahoo.co.uk
Tue Mar 6 00:10:30 PST 2007

Gallileo GIOVE-A navigation signal available to users

From: http://www.esa.int/esaCP/SEM4EDN0LYE_index_0.html 

The GIOVE-A Signal-in-Space Interface Control Document, the document that gives
the technical details of the signals transmitted by the GIOVE-A satellite, has
been released. This will allow receiver manufacturers and research institutions
to use a real signal for their research and development.
Following the launch of GIOVE-A on 28 December 2005 from the Baikonur
Cosmodrome and the transmission of the first Galileo signals from medium Earth
orbit on 12 January 2006, ESA and Surrey Satellite Technology Limited (SSTL –
United Kingdom) have completed the GIOVE-A in-orbit validation activities. The
GIOVE-A signal validation has been accomplished through a network of 13 Galileo
Experimental Sensor Stations (GESS), deployed world wide, and a GIOVE
Processing Centre which computes precise orbits and clock timings for the GIOVE
satellites, based on the measurements made by the GESS and satellite laser
ranging stations.  
GIOVE-A L1 in-band spectrum 
The GIOVE-A Signal-in-Space Interface Control Document (SIS-ICD) is the key
document that will allow any user to build a receiver able to track GIOVE-A
signals, interpret the navigation message and compute the distance between the
satellite and the receiver. Following the successfully in-orbit validation
mission, ESA has decided to release the SIS-ICD to the public to allow receiver
manufacturers and research centres to benefit from experiments with a real
Signal-in-Space for research and development purposes. 

This is possible since the nominal GIOVE-A navigation Signal-in–Space (SIS) is
fully representative of the future Galileo navigation signals, on all three
Galileo frequency bands, even though GIOVE-A uses specific spreading codes that
are different from the nominal codes of the final Galileo constellation to
allow unambiguous identification of the spacecraft. These codes are described
in the GIOVE-A public document and with knowledge of them the GIOVE-A signals
can be used for code and carrier phase tracking in precisely the same way the
future Galileo signals will be used. All GIOVE-A signal spectra are identical
to the future Galileo navigation SIS spectra. 
GIOVE-A E5 in-band spectrum  
The navigation data symbol rates are identical with the nominal Galileo data
rates for all public signals, and the same principles as in the final Galileo
navigation signal are used for message encoding. The navigation message
structure of GIOVE-A is different from the future Galileo navigation signal,
but the low level elements of the message differ only in minor details. The
content of the GIOVE-A navigation message is complete with all ingredients such
as, for example, ephemeris and clock correction, that are needed for
pseudo-range calculation and further positioning processing, thus leading to a
full set of navigation signals. 

The time for simulation is over, so the ESA Galileo project team is putting at
the disposal of the user community the information needed to support the
validation of demanding Galileo user applications with a real satellite. 

The GIOVE-A Signal-in-Space ICD is available at the GIOVE web site:
73 Trevor M5AKA
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