Engineers are now assessing the signal coming down to Earth.
They will be looking for any indications that it is affected by its passage through the atmosphere, and checking that it does not interfere with any systems that use neighbouring bands of the electromagnetic spectrum.
A fundamental focus in coming days will be the in-orbit behaviour of Giove-B's passive hydrogen maser clock.
It is the most stable clock ever put in permanent orbit, and is designed to keep time with an accuracy of better than one nanosecond (billionth of a second) in 24 hours.
As well as this and its two other atomic clocks, the demonstrator will check the generation of signals across the full spectrum that Galileo intends to use for its five sat-nav services.
Once engineers are happy with all this, the way will be clear to launch the first four satellites in the eventual constellation. These so-called In-Orbit Validation (IOV) spacecraft are expected to fly in 2010.
"We're extremely proud of the critical role we have played on Giove-B, being responsible for the payload and ground segment," commented Dr Mike Healy at UK Astrium.
"'Hearing' the new signal broadcast - this was a major step forward in creating Galileo. It's full speed ahead now for the IOV satellites," he told BBC News.
The Galileo programme itself has seen its timeline slip on a number of occasions, and has come close to being abandoned.
Europe has already spent 1.6bn euros ($2.5bn; £1.3bn) on the project, and ministers have warned that the additional 3.4bn euros ($5.3bn; £2.7bn) recently approved for sat-nav investments will be the limit on expenditure.
Galileo is envisaged as being technologically complementary to GPS, and is touted as a key high-technology venture for the EU.
Esa says that compared with using GPS alone, the combined systems "will provide higher accuracy in challenging environments where multipath and interference are present, and deeper penetration for indoor navigation".
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