The threat of GPS jamming on infrastructure

Global Positioning System (GPS) devices use signals transmitted by a network of orbiting satellites to locate, track and navigate positions. Many electronic systems contain GPS technology; its versatility makes it valuable to a range of industries. Yet, GPS is also vulnerable to interference from benign and malicious sources. Protecting these systems from jamming is now key to the security and daily operation of our infrastructure.

In an incident in 2009, Newark Airport in the United States found repeated interference occurring in some of their GPS-based systems. It took three months to trace the problem back to a truck driver using a GPS jammer. This highlighted a clear lack of suitable equipment to detect jamming devices.

Cases of interference have increased as we become more reliant on GPS as a society. Jamming doesn't just threaten security; it can also have significant economic impact. For example, it could affect import and export industries through shipping and transportation. There are also implications for the aviation industry, the military and service industries such as mobile phone networks. Even banking transactions use GPS-derived timing. More critically, our emergency service communications rely on GPS. Finding a better way to detect jamming and identify the cause could reduce this threat and help protect against it.

Isolating and distinguishing GPS signals

Professor Cathryn Mitchell and Dr Robert Watson took up this challenge by leading research into GPS signal processes. They measured radio-frequency signals passing through the ionosphere, otherwise known as ionospheric scintillation. They focused on the signals coming from GPS receivers and analysed the data to identify anomalies.

The team developed statistical methods that could differentiate between environmental effects and anomalous interference. From these findings, they were able to design new algorithms that were sensitive to abnormal behaviour.

The research has enabled the team to isolate anomalies and discriminate between different causes. In some circumstances, they can also pinpoint locations. This helps identify whether the GPS jamming is due to natural environmental phenomena, such as space weather, or from intentional malicious activity.

Improving how we detect GPS jammers

The fundamental research findings led to the Technology Strategy Board (TSB) project SENTINEL. Working with Chronos Technology, our researchers developed interference detection monitor (IDM) sensors. These identify the location of GPS jammers in real-time, providing quick detection and protection.

The IDMs are in use across the UK in airports, ports and other sensitive locations. They provide timely detection and warn of any threats posed by the natural environment or from criminal activity.

The success of this research is seen in its commercial and policy impact. It has influenced legislative change towards making the possession of GPS jammers illegal. It also continues to benefit industry with Chronos Technology using the results to develop and market further products. These include handheld GPS jamming detector and locator systems, and the Signal Sentry 1000™ mesh networks that can geolocate a moving or stationary jammer.

Making an impact

This research was part of our REF 2014 submission for Electrical and electronic engineering, metallurgy and materials.