The European initiative to build a system of satellites to rival the US GPS system, has finally been given the go-ahead.

Last Friday, European nations involved in the project agreed to build a 3.4 billion euros (£2.42 billion)-satellite navigation system, which the EU hopes will allow it to achieve "strategic independence" from the United States.

For the past several years, the troubled Galileo project has been attempting to build a 30-satellite system. However the consortium of European companies in charge of the project, have been squabbling over the 2.4bn euros (£1.7bn) construction costs to which they were supposed to commit.

Political infighting and doubts about the project's financial viability threatened to derail the project, and it has taken the last minute invention of European finance ministers, who have decided to commit €2.4bn out of public funds (mostly from the coffers of the massive EU agriculture budget).

The network of 30 satellites will be controlled by two ground control stations in Germany and Italy. A third, largely superfluous control station will be built in Spain, by the Spanish tax payer, after the Spanish government’s attempt to win last minute concessions was overruled in the final agreement.

Europe has been keen to pursue the Galileo project, and remove its dependence upon the GPS system, which is controlled by the US military. GPS signals are carried on a US military network of 24 satellites, but the fear is that they can be turned off in the event of war, although the US denies this.

Galileo is hoped to be up and running by 2013 (currently only one non operational satellite is in orbit).

Galileo hopes to differentiate itself from GPS by offering a more accurate (down to one metre) signal. Users will also not be subject to the risk of the signal being shut down, and Galileo hopes to offer a guaranteed service to users equipped with Galileo-compatible receivers.

This will allow Galileo to offer for example, navigation and search and rescue services on a global basis. Galileo satellites will be able to pick up signals from emergency beacons carried on ships, planes or persons and ultimately send these back to national rescue centres. The idea is that at least one Galileo satellite will be in view of any point on Earth, so near real-time distress alert is possible. In some cases, feedback could be sent back to a beacon, something which is only made possible by Galileo.

It is envisaged that Galileo will offer four levels of service. The Open Service (OS) will be free of user charge, and will provide position and timing performance "competitive with other GNSS systems." The second offering is a Safety-of-Life Service (SoL) signal, which improves the open service performance through the provision of timely warnings to the user when it fails to meet certain margins of accuracy (integrity). It is envisaged that a service guarantee will be provided for this service.

The third service is a Commercial Service (CS) that provides access to two additional signals, to allow for a higher data throughput rate and to enable users to improve accuracy. The signals are encrypted. It is envisaged that a service guarantee will also be provided for this service.

Finally, the Public Regulated Service (PRS) provides position and timing to specific users requiring a high continuity of service, with controlled access. Two PRS navigation signals with encrypted ranging codes and data will be available.

Galileo will not be alone however, with a number of rivals. The well-established US GPS system, used in nearly all satellite navigation systems, is currently being upgraded, China is building its own network, and the Russian Glonass system, which has a fairly limited geographical range, is being improved.