GPS signals are disrupted in Russian cities
There are relatively few large-scale monitoring efforts that track GPS interference. John Wiseman, the technologist and open source enthusiast who created GPSJam, says the system works by looking at ADS-B signals sent by aircraft flying around the world – the signals used by aircraft to tell people where they are and to to allow them to be tracked. As part of ADS-B data, an aircraft’s GNSS signal strength can be recorded.
Wiseman says GPSJam, which launched in July after he began collecting data in mid-February, uses ADS-B data from the ADS-B Exchange, a network of aviation trackers that track aircraft. This is usually GPS data, but it can also be other GNSS data if an aircraft uses a different system. Wiseman then aggregates this data each day to show areas where there appears to be GPS interference.
The GPSJam map shows potential interference in red hexagons across a world map, while areas where there may be less interference are shown in yellow, and green hexed areas represent no interference. The system is able to classify areas only where aircraft have flown over and where ADS-B data has been collected. Since the start of the war in Ukraine, planes have not flown over the country’s airspace.
“Most of the red zones that are regularly there correlate with places where people have documented GPS interference in the past,” says Wiseman. (He has previously built several open-source aircraft tracking tools.) “It’s really just measuring aircraft. There are stories where people on the ground and some of these regions don’t notice anything.” In the recently affected cities, there have been some Russian-language social media posts discussing power outages, although it’s unclear how much GPS has been disrupted on the ground.
Todd Walter, director of the GNSS laboratory at Stanford University, says GPSJam is a “valuable resource” for those tracking GPS interference. “It’s a good method to quickly see where jamming is prevalent,” says Walter. Together with other researchers at Stanford, Walter has previously documented how ADS-B data can be used to track GNSS disturbances. Despite the technique working, Walter says, there are limitations to using ADS-B data to track GPS violations.
“It’s not very good at detecting weak jammers or jammers on other frequencies,” Walter explains, adding that an aircraft’s body can shield potential sources of jamming, making it harder to detect smaller, localized sources of GPS jamming . “Areas that are green on GPSJam are not necessarily free of GPS jams,” he adds.
GPS interference can also be monitored from space. Data provided to WIRED by Aurora Insight, which uses satellites to detect GNSS disturbances, shows an increase in signal strength in eastern Russia in recent weeks, compared to measurements taken in August. “Increases in GPS signal levels have the potential to interfere with some types of GPS receivers,” the company says, noting that this does not explicitly mean that interference or jamming has occurred.
Throughout Russia’s full-scale war in Ukraine, the forces have attempted to control the information space and communications. The hack against the ViaSat satellite system disrupted satellite connections across Europe. Cities have had telephone equipment destroyed by missiles, and in some occupied areas Russia has attempted to take control of Ukraine’s internet, subjecting people to censorship and surveillance. (At the same time, Russia has been hacked on an unprecedented scale.)