From ship navigation to financial transactions, we’re increasingly reliant on GPS. Jamming and spoofing can therefore cause significant disruption and represent a public safety threat. Fortunately, spectrum monitoring allows detection and location of jammers and the possibility to pre-empt attacks with anti-jamming and anti-spoofing technologies.
During an L1 and L2 GPS band monitoring campaign over just a few weeks in London, we detected significant jamming activity. This ranged from crude unmodulated sources of interference poorly centered on the L1 or L2 band to synthesized sources suggesting deliberate targeting.
A common use of jammers in London is taxi and HGV drivers evading rules on maximum driving hours or trying to stop employers from tracking them. In other parts of the world, GPS jamming has been used for more sinister purposes. South Korea was subject to a major campaign of GPS jamming from North Korea in 2016, affecting ship and aircraft navigation.
Whatever the target of a GPS jammer, the devices do not discriminate, so there is usually additional collateral damage. Air Traffic Control (ATC), search and rescue operations, the electric grid and mobile phone services are all vulnerable to GPS jamming fallout. The London Stock Exchange has been subject to repeated GPS outages, affecting timestamping of financial transactions. In 2007, a navy exercise on loss of GPS communications in San Diego harbor meant that residents of the city were unable to withdraw cash from ATMs and doctors’ emergency pagers stopped working – it took 3 days to identify the ships as the cause. As jamming activity from civilian users becomes more prevalent, we risk similar disruptions as well as more fatal incidents such as aircraft colliding over populated areas.