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| Preparing the adapter between Soyuz
and Giove-A. Credits: ESA |
Gallileo GIOVE-A navigation signal available to users
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.
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GIOVE-A on the
launch pad Credits: ESA |
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: http://www.giove.esa.int/
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