GPS: How Can We Protect The System On Which So Many Important Services Depend?

On September 1 last year, the Financial Times reported that Ursula von der Leyen's plane, traveling from Warsaw to Plovdiv the previous day, had encountered difficulties during landing, probably due to GPS signal interference. Although the president of the European Commission eventually landed safely, and there is conflicting information about how serious the GPS problem was – in fact, there is no evidence that anyone actually deliberately jammed the aircraft's instruments – the interpretation of what happened shows that such an incident is quite easily conceivable today.

And rightly so, because the system is particularly vulnerable. It is threatened by both jamming and spoofing attempts, according to the presentation of Integricom Hungary CEO Bastiaan Ober, given at a workshop entitled GNSS Under Attack, organized at BME.

In satellite positioning, the receiver picks up signals from several, even 30-40 satellites at once and determines its own position relative to the known positions of the satellites based on the distances calculated from the signals received. The service commonly referred to as GPS is actually called the Global Navigation Satellite System (GNSS): GPS is the American system, which has Russian (Glonass), EU (Galileo), and Chinese (BeiDou) equivalents.

The fact that this is critical infrastructure is no longer news to anyone. Nearly 7 billion devices are connected to it worldwide, and a range of important services and even key sectors depend on it. 

It's not just smartphones: even power grids rely on satellite signals, 

explained Mr Ober. In 2021, consulting firm London Economics calculated that a one-day GPS outage would cause £1.4 billion in damage in the UK, and a week-long outage would result in losses of £7.6 billion.

Moreover, since its efficiency and convenience have greatly reinforced our trust in it, we tend to treat GPS as an objective, infallible authority. When it misleads, it does so in a very convincing way, which is why some users believe it even when physical reality seems to contradict it. However, as Mr Ober pointed out, 

GNSS can be inaccurate, inaccessible, misleading—and exposed to attack.

Among the potential vulnerabilities, the most alarming is undoubtedly the possibility that satellite navigation could become the front line of electronic warfare. It is clear that GPS signals are being jammed not only in war-torn regions, but almost everywhere in the world, primarily to prevent GPS-based fleet tracking and to avoid road tolls.

Professor Philipp Berglez presented published cases in which GPS receivers showed that all ships in a given area were going around in circles. This kind of manipulation can be done with relatively easily accessible tools, and the necessary technical knowledge is not out of reach either. The European Union is therefore drawing up an action plan to address security threats, including the deployment of additional satellites, improving detection capabilities, and increasing the resilience of critical infrastructure.

But how can these tools be tested without endangering others? Such experiments are usually carried out in the shadows of the high cliffs of remote fjords of Norway, for example, Bence Takács, associate professor at the Department of General and Higher Geodesy of the Faculty of Civil Engineering, told bme.hu. He added that it is also possible to conduct tests under laboratory conditions, and the simulator and signal generator required for this were presented by Emerson NI employees. The development of the devices was supported by the European Space Agency, so companies and research institutes can also use them.

Rector's Office, Communications Directorate
photo: Viktor Hankó