PRS means secure satellite navigation for sensitive applications21 March 2011Until now, secure GNSS services have been accessible only to defence users and, in the case of GPS, with the consent of the United States. But there are many GNSS applications that could benefit from a high level of security, including those serving critical civil infrastructure, law enforcement officers, transport operators, financial institutions and many others. The Galileo PRS (Public Regulated Service) is a secure satellite navigation service that, unlike others, is designed for users in the civil sector.  Police need secure GNSS signal © Peter Gutierrez © Peter Gutierrez There has been a lot of talk recently about the Galileo 'PRS' – what it is and what it is not. The reality is less complicated and probably less sinister than some have tried to suggest. Essentially, the PRS will be an encrypted signal that will be used by European government agencies, including emergency services, police, and, if it suits their needs, the military. It is designed to provide positioning and timing to users requiring a high level of continuity of service, with controlled access ensured through data encryption. Where and why it all startedThe American GPS satellite navigation system began as a military system for military use, and it remains under the control of the US military. It does include an open signal that can be accessed by anyone, including public and private non-military users around the world. Indeed, the GPS open signal has become the basis of a global market now worth billions of euros. But GPS also comprises a secured signal that can be accessed only by those with special clearance and in possession of the necessary decryption tools. Access to this secured GPS signal remains under the control of the US military and is not available to civil users.  PRS for critical infrastructures such as airports © Peter Gutierrez The European Galileo system was conceived in a very different manner; it was conceived and designed by civil authorities for civil use, and it will always remain under the control of civil authorities. Like GPS, it will include an open signal, accessible to anyone, and a secured signal, accessible to those with clearance and in possession of the necessary decryption tools. Why do we need secure satellite navigation signals?The main weakness of the open GPS signal today is its vulnerability to 'jamming'. A GPS jammer is a simple device that sends out a radio signal at the same frequency as the satellite signal, essentially covering the satellite signal. A relatively small and inexpensive jammer, now available on the open market, can easily disrupt the GPS signal in a limited area. More powerful jammers could disrupt signals in close proximity of airports, for example. This possibility has led to fears that terrorists could use such devices to disrupt air traffic, with severe safety and economic consequences. GPS jammers foil the police…The latest GPS jamming devices are now being used by car thieves in the UK to render stolen cars and trucks undetectable by law enforcement. As GPS satellite signals are intrinsically weak, a jamming device that puts out just one watt of power is sufficient to disrupt the GPS signal in receivers within several kilometres. This leaves an in-vehicle system unable to establish its position and report back to a GPS tracking centre, where the vehicle is registered. When a signal is jammed, the user knows that there is a problem, because the signal is obviously disrupted, and he or she can switch to another means of navigation. But there is a second, more disturbing method of GPS disruption, called 'spoofing', where a false GPS signal is created that passes as a real GPS signal. The user sees what appears to be a genuine signal and is unaware that anything is wrong. Whether driving a car, navigating a ship or piloting an aircraft, the user will continue to refer to and behave in accordance with the incorrect positioning information. As one can imagine, the potential consequences of spoofing are much more serious than in the case of jamming. Protecting the signalUS and allied defence forces use GPS extensively in combat situations, to record their positions and those of their enemies. Jamming devices in the wrong hands could have a severe impact on these forces during both ground and air operations. That is why the US military has its own secured GPS signal that can resist jamming. Civil authorities also vulnerableThere is no doubt that today's defence navigation systems need to be secure, but many other systems, under civilian control, are equally critical and are just as vulnerable. Emergency networks, power stations, and airports that rely on accurate GPS signals would be seriously affected if a powerful jamming signal was used at these locations. In addition, the global financial system, managing transactions worth many billions of euros every day, is now heavily dependant on critical time-stamping capabilities made possible by GPS. With the PRS, for the first time, non-defence-related users of satellite navigation will be protected by the same kind of secured systems currently reserved only for users of the US military GPS signal.  Reliable location information for emergency services © Peter Gutierrez The Galileo PRS is specifically designed to be more resistant to both jamming and spoofing. It will be more costly and more difficult to attack PRS receivers, because the level of power required to jam the signal will make jammers more expensive to produce and easier to locate when in use. In parallel, robust encryption mechanisms within the PRS signal will enable positive protection against spoofing. Summing upThanks to the robustness of the PRS signal, users will be protected on a daily basis against attacks, especially jamming and spoofing. Simply put, the PRS will extend to a whole range of important services the high level of protection and reliability they need to defend and ensure the prosperity of businesses, critical infrastructure and citizens everywhere. More Information:'EU-funded project moves forward on Galileo PRS standards' |