The pioneer spacecraft in Europe's satellite-navigation system, Galileo, has taken a major step towards securing the network's allocated frequencies.
Giove-A will demonstrate key technologies
Giove-A transmitted the first of its navigational signals to ground stations in the UK and Belgium on Thursday.
The UK-built satellite was launched on 28 December from the Baikonur Cosmodrome in Kazakhstan.
It is a demonstrator for the network that will give Europe its own version of the US Global Positioning System.
Giove-A was placed into orbit some 23,000km (14,292 miles) above the Earth.
Within hours of the launch, engineers at Surrey Satellite Technology Ltd (SSTL) began activating its functions and making sure it was fully operational.
"We have now reached the point where we've started to validate the whole Galileo signal," Philip Davies of SSTL told the BBC News website.
"Thursday was the first day when the first actual Galileo signal was sent from space to Earth.
"If you had receiving equipment, you could have picked it up anywhere on Earth within visibility of the satellite - we picked it up in the UK at the Chilbolton Observatory in Hampshire."
Mr Davies said people had been working around the clock at the control room in Guildford, Surrey, to check out the satellite's payload.
"You are at the mercy of celestial mechanics - you do your job when the satellite's overhead," he said.
Giove-A was carried into orbit on a Soyuz-Fregat launch vehicle
The Galileo signals transmitted by Giove-A will now be analysed in detail to make sure they satisfy the criteria set by the International Telecommunications Union.
The 3.4bn-euro (£2.3bn; $4bn) partnership project between the European Space Agency and the European Commission will give civilian users a satellite navigation and positioning service that is 10 times more accurate than the alternatives available today.
While public signals from GPS are already widely used by the likes of sailors, mountaineers and motorists, the US military reserves the right to limit its use or switch it off for security reasons.
"The first signal from Giove-A heralds a new era for location technologies," said Francis Tuffy, director of the new Location and Timing Knowledge Transfer Network (KTN), which was set up by the UK's Department for Trade Industry (DTI) to help industry to benefit from the Galileo signal.
"The ability to pinpoint the location of people and objects provides huge opportunities - from personal navigation to safety on the railways.
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"But it is up to UK industry to make Galileo work for us and this requires a joint effort from academia, industry and government.
"If we can create real applications which use the strength of the Galileo signal, we could be looking at the creation of a whole new industry."
On Thursday, South Korea became the latest non-European Union country to sign up to a Galileo cooperation programme, alongside China, Israel and Ukraine.
"Korea's support for Galileo is an important milestone for the project," said Francis Tuffy.
"The backing of such a leader in technologies such as mobile telecommunications demonstrates to UK firms the worldwide potential for location technologies. Now it is up to us to turn this support into commercial results."