GIDAS: Real-time interference detection making satnav safer
A new monitoring system developed through an ESA-backed project works like a ‘bodyguard’ for satellite navigation in use at strategic or safety-critical sites. Known as GIDAS, the scalable system immediately detects, identifies and pinpoints satnav interference sources in its vicinity.
It is estimated that there are currently the same number of satnav receivers on Earth as there are people. Positioning, navigation and timing signals from space-based constellations such as Galileo and GPS form an invisible, essential infrastructure, underpinning numerous modern aspects of modern life: communications, power and transportation.
Satellite navigation helps guide a growing number of aircraft, boats, trains and autonomous vehicles. Meanwhile satnav-based time-stamps authentic multi-billion euro financial transactions, and coordinate the synchronised running of power grids. Satellite navigation is always on, available everywhere on Earth, so it is easy to take its availability for granted. But as crucial as these signals from space are, they are also vulnerable to ground-based interference.
“It’s simply a matter of output power,” say Andreas Lesch of Austria-based OHB Digital Solutions. “A navigation signal on the ground is equivalent to the light from a 60 watt lamp aboard a satellite, some 23 222 km away in space in the case of Galileo. So these faint signals can be jammed by more powerful local radio signals, either accidentally or deliberately, or even misleading fake navigation signals, known as ‘spoofing’.
“Our new GNSS Interference Detection and Analysis System, GIDAS, is designed to safeguard critical infrastructure against jamming or spoofing, by performing continuous monitoring of key signal bands. By doing so, GIDAS can raise the alarm in real time, identify the type of interference then pinpoint the location of these dangerous portable devices causing the interference so the authorities can take immediate remedial action.”
GIDAS can provide interference detection and directionality with a single reporting station, although a minimum of three stations are required for pinpointing interference sources, linked to an overall monitoring centre. Monitoring centres can also be connected together, making the GIDAS system easily scalable, from safeguarding an individual harbour, airport or system critical site up to an entire city or region.
“People are only now catching up to the seriousness of this problem,” adds Andreas. “Surveys of the highest-density parts of Europe surveys report around three to four jammers hourly.
“These small devices are technically illegal but are easily available online for a few hundred euros or less, often marketed as ‘personal privacy devices’. Jammers are sold as having a range of only a few metres, but can turn out to have a practical range of dozens of metres or more – leading to unintentionally widespread interference, like the famous jammer-equipped US truck driver who shut down Newark Airport navigation systems whenever he drove past.
“Spoofing is more serious still, with a strong criminal element, where false satellite navigation signals replace real ones, to mislead receivers about their position, employed in the past to down put drones or divert boats.
“Working in this field for eight to nine years, we have seen a strong growth in interference, even as GNSS becomes ever more crucial. With our passion for GNSS and signal processing, we decided to something practical to combat this development, delivering rapid detection, classification and localisation of interference to our customers.”
GIDAS was developed by OHB Digital Solutions and Joanneum University through ESA’s Navigation Innovation and Support Programme (NAVISP), working with European industry and academia to develop innovative navigation technology.
“The company initiated the project through NAVISP’s second element, focused on strengthening European competitiveness in the navigation arena, proceeding on a co-funded basis,”says engineer Thomas Burger, overseeing GIDAS project for ESA. “The plan was to enable a commercially attractive business to get started, and I’m happy to say we made it.”
“Considering the budget, the project had a wide scope, including the development of a multi-constellation GNSS receiver with all processing stages, an extended digital front end for jamming and spoofing detection, processing blocks transferred to a parallel processor based on a customised fully programmable gate array.
“And that was only one ingredient of the overall GIDAS system, also including the actual interference detection machinery, the interference locating subsystem, and all the communication, database, and graphical user interface elements needed to create a distributed, human-usable system – which is able to go on working autonomously, only asking for human involvement when events are detected.”
Following the conclusion of the two-year NAVISP project, GIDAS is now in the process of being rolled out to several Europe-based governmental and private sector customers.
