There are relatively few large-scale monitoring efforts tracking GPS disruptions. John Wiseman, the technologist and open source enthusiast who created GPSJam, says the system works by looking at ADS-B signals that are sent by planes flying around the world—the signals are used by planes to let people know their location and to allow them to be tracked. As part of ADS-B data, a plane’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 ADS-B Exchange, a network of aviation followers who track planes. This is generally GPS data, but it can also be other GNSS data if a plane 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 hexes across a world map, while areas where there may be some smaller interference are shown in yellow, and green hexes represent no interference. The system is able to classify areas only where planes have flown over and where ADS-B data is collected. Since the start of the war in Ukraine, planes have not been flying over the country’s airspace.
“Most of the red zones that are regularly there correlate with places where people have previously documented GPS interference,” Wiseman says. (He has previously built multiple open source flight tracking tools.) “It’s really just measuring aircraft. There are stories where people on the ground and some of those regions aren’t noticing anything.” In the cities recently impacted, there have been some Russian-language social media posts discussing outages, although it is unclear how widely GPS has been disrupted on the ground.
Todd Walter, the director of the GNSS laboratory at Stanford University, says GPSJam is a “valuable resource” for those tracking GPS interference. “It is a good method to quickly see where jamming is prevalent,” Walter says. Along with fellow researchers at Stanford, Walter has previously documented how ADS-B data can be used for tracking GNSS disruptions. Despite the technique working, Walter says, there are limitations to using ADS-B data to track GPS outages.
“It is 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 blocking, making it harder to detect smaller, local sources of GPS blocking. “Areas that are green on GPSJam are not necessarily free of any GPS jamming,” he adds.
GPS disruptions can also be monitored from space. Data provided to WIRED from Aurora Insight, which uses satellites to sense GNSS disruptions, shows an increase in signal strength in western Russia in recent weeks, compared with measurements taken in August. “Increases in GPS signal levels have the potential to interfere with some types of GPS receivers,” the company says, pointing out that this does not explicitly mean interference or jamming has taken place.
Throughout Russia’s full-scale war in Ukraine, its forces have attempted to control the information space and communications. Its 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 tried to take control of Ukraine’s internet, subjecting people to censorship and surveillance. (At the same time, Russia has been hacked at an unprecedented scale.)