A duplication of effort?

European Union Transport Ministers meeting in Brussels have given the go ahead to the Galileo satellite system. But why do we need another system to compete with the American GPS?

European Union Transport Ministers meeting in Brussels have given the go ahead to the Galileo satellite system. But why do we need another system to compete with the American’s GPS?

Developed by the European Space Agency (ESA) in collaboration with the European Union and co-funded by the two organisations on a 50-50 basis, Galileo is designed to be operational from 2008 and to provide an accurate, secure and certified satellite positioning system.

However, not everyone is impressed. The US Government has said that it sees no compelling need for the EU Galileo satellite system, because its own GPS system is expected to meet the needs of users around the world for the foreseeable future. The EU of course disagrees and the issue now is one of compatibility.

GPS satellites emit signals that can be converted by users anywhere in the world into precise timing and positioning information. There are at present two radionavigation satellite networks in the world, one American (GPS), and one Russian (Glonass). Both were designed as military systems. Now that the Russian system is on the way out without having generated any real civil applications, GPS offers the only real alternative – at present.

But Galileo, a billion Euro project, of course is on the way in, offering a real alternative to the establishment of a de facto monopoly in favour of GPS.

Before Galileo gets off the launch pad, however, the US GPS system will enter an extensive modernisation program to provide even better service to its existing GPS users.

Already the accuracy of the GPS civil service is between 10-20 metres. The next step involves new satellites that will broadcast two new civil signals: one of which will be introduced in 2003, the other in 2005. The added signals will improve accuracy to 3-5 meters. Additional upgrades are being planned for the next generation of satellites, known as GPS III.

Users who need even greater accuracy and integrity can take advantage of US government augmentation services, such as the Wide Area Augmentation System (and similar European and Japanese systems), the Local Area Augmentation System, commercial augmentation services, and advanced processing services. These services allow millimetre-level accuracy.

So at first glance, the EU Galileo project looks like a duplication of effort. So why do we actually need it?

Representatives of the EU claim that without Galileo, in 10 or 20 years, the entire world navigation system will be subject to an American monopoly. This, the EU says, represents a threat to a major proportion of EU industry as all means of transport need electronic or positioning functions.

The EU claims that systems containing standard radionavigation receiving components are already subject to US domination and that trend will become stronger yet unless something is done about it.

The US GPS itself is a dual-use system, designed to support both civil and military users. The system consists of a minimum of 24 satellites and associated ground support facilities.

The Galileo project, on the other hand, is ‘purely commercial’ and would comprise thirty satellites, distributed over three planes in Medium Earth Orbit. Data transfer to and from the satellites will be performed through a global network of Galileo Up-link Stations (GUS), each of which combines a Telemetry, Telecommand & Tracking Station (TT&C) and a Mission Up-link Station (MUS). Two Galileo Control Centres will be set up in Europe to monitor the operation of the satellites and manage the navigation system.

Users in Europe, North America, and around the world will obviously benefit if the Galileo system is designed and built so that it is compatible and interoperable with GPS. This requires, among other things, establishing Galileo’s technical parameters (for example, signal structure and radiofrequency selection) so that GPS service is not adversely affected.

To ensure interoperability and mutual benefits, the United States has proposed an agreement on GPS-Galileo co-operation.

A US team has been discussing the proposed agreement with a European Commission-led delegation since October 2000. These talks are likely to continue at least through the end of 2002.

The US delegation has emphasised that it would be unacceptable for Galileo to overlay the same portion of the radiofrequency spectrum used by the GPS military service.

The US delegation has added that it would also be opposed to anything that would degrade the GPS signals (civil or military), diminish the ability to deny access to positioning signals to adversaries in time of crisis, or undermine NATO cohesion.

The US takes the view that all non-military satellite radionavigation signals, including a primary Reference Source (PRS), can be used for hostile purposes, even for terrorism.

The problem is that International regulations authorise Galileo to use the same frequencies as those carrying the GPS military signal on condition that Galileo does not ’cause disturbance in the American system’.

Optimising the use of Galileo’s allotted frequencies involves some ‘superimposition’ with band L1 which the US wishes to use in future for their military operations.

If, however, the same frequencies are used both by Galileo’s non-military PRS and the GPS’s military signal then it will not be possible to selectively jam one of the two signals without disrupting the other.

The US, however, does want to have the option of jamming the PRS without disrupting its own military Global Positioning System (GPS).

The EU says that a solution is to ensure that the Galileo PRS is encrypted using a government cipher and monitored by an appropriate European political body.

At the last round of talks in Washington at the end of October 2001, the European negotiators suggested some solutions for the use of the radiofrequency spectrum which would take the Americans’ concerns into account.

The solutions put forward by Europe claim to allow this superimposition without generating ‘unacceptable’ interference for the military signal. In addition, the proposed solutions are flexible enough to take American security concerns into consideration.