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New threats to GNSS require new approaches to receiver testing


Blog - New threats to GNSS require new approaches to receiver testing

With RF interference and spoofing attacks both on the rise, GNSS receiver developers must be able to simulate new threat sources in the lab.

It’s notoriously difficult to predict how GNSS threats will evolve. But for developers of GNSS receivers, an up to date understanding of the threat environment is crucial.

Protecting your customers, end-users, and – ultimately – your business means doing everything possible to ensure the highest levels of robustness and resilience.

In this blog I’ll explore the current and emerging threats as I see them, and look at how receiver developers can stay abreast of those developments in their testing.

Satellite over earth

From drone defences to military exercises: new sources of RF interference

Radio frequency interference may not be a new threat, but its impact on GNSS positioning, navigation and timing (PNT) receivers is set to grow and grow.

One emerging source of RF interference may, ironically enough, be new technologies deployed to keep critical infrastructure safe. Recent drone incursions at Gatwick, Heathrow and Newark Airport have led to demands for anti-drone systems to be installed near airports and other critical infrastructure.

In addition to the drone’s telemetry and radio control links, some of these systems will likely actively target and jam the drone’s GNSS receiver. That creates a clear capacity for unintended consequences in terms of collateral damage to nearby GNSS-reliant systems like landing systems and air traffic control – potentially disrupting the very services anti-drone systems are designed to protect.

Another source of increased RF interference is state-sanctioned jamming – either to disrupt an adversary’s activities (as seems to be happening regularly in the far north of Norway) or as a key element in military exercises, where signals may be deliberately degraded to test the performance of national security systems.

In February 2019, for example, the Federal Aviation Administration warned that GPS and ADS-B could be compromised on five consecutive days across Florida, Pennsylvania and Louisiana, while the US military conducted training off the coast of Georgia.

Finally, there’s the growing use of jammers by rule-flouting individuals (like truck drivers who don’t want to be tracked, or taxi drivers who want to take out the Uber-driving competition) and organised criminal gangs.

As criminals realise quite how easily GNSS-enabled devices can reveal their current position – or simply prove where they’ve been – GNSS jamming is providing a crude but effective way to conceal their movements. And with increasing adoption of GNSS-dependent infrastructure like electronic border technology (as we’re seeing, for example, in Jordan, Kenya, Rwanda and Uganda) the uses and impact of criminal jamming are only going to multiply.

Significant impact on commercial aviation

Just how big a problem is this upwards trend in RF interference? There’s already evidence of its impact on commercial aviation, with more and more pilots experiencing issues worldwide.

A January 2019 study by the Airline Owners and Pilots Association found that more than 64 percent of the pilots surveyed had concerns about the impact of interference on their use of GPS and ADS-B. What’s more, Eurocontrol reported more than 800 incidents of GPS interference in the Eastern Mediterranean region in 2018 alone, while my own searches of NASA’s Aviation Safety Reporting database revealed that air crew have reported more than 250 episodes of GPS disruption since 2013.

GNSS spoofing is on the rise

The other key threat to get to grips with is GNSS spoofing. Launching a successful spoofing attack used to require significant financial investment and specialist expertise. Today, however, the cost of the required components has plummeted, recipes for building a spoofer are readily available online, and all the code needed to program one can be easily downloaded from any number of sites.

Criminals are now actively spoofing their location, either at the RF level or at the software application level, to fool:

There’s also evidence that governments may be employing spoofing technology to stop drones overflying sensitive areas, as observed in Moscow in 2016 and in the Black Sea in 2017. Such anti-drone spoofing will, like anti-drone jamming, inevitably have unintended consequences.

Threat mitigation measures are increasing

As RF interference increases and spoofing becomes more widespread, there’s likely to be growing demand for receivers with proven multi-GNSS and multi-frequency capabilities, which – because of their ability to process a greater range of signals – can offer greater resistance to such threats.

Other threat mitigation methods include signal authentication, specialist antenna designs, and in-built anti-jam and anti-spoofing algorithms. For some uses, like European public safety and emergency services, receiver developers may also be able to take advantage of the extra security offered by Galileo’s encrypted Public Regulated Service (PRS) signal.

Flexible and future-proof simulation is essential

Testing the receiver’s robustness (resistance to interference) and resilience (ability to recover from an error state) will be critical. Developers will want to test receiver performance in the complex environments in which they’ll be used – and where any number of threats might occur at once.

The good news is that, thanks to interference detector technology, there’s growing understanding of the characteristics of these different RF interference events, and a growing library of real-world interference waveforms that developers can re-create with simulation equipment in the lab.

Spirent is committed to enabling receiver developers to re-create a broad range of natural and manmade interference scenarios in the lab, using our GSS7000 and GSS9000 multi-constellation, multi-frequency simulators together with our GSS7725 interference generator. We also offer a comprehensive suite of threat test scenarios; test automation to enable broader and faster test coverage; and expert advice on protecting receivers against emerging threats.

Spirent’s commitment to offer all of the latest signals and ICDs in our simulators, and to stay abreast of new threat sources as they arise, means developers can be assured of a flexible, future-proof simulation platform to help protect and toughen their receiver designs.

Questions about testing receivers with the latest threats? Get in touch

If you’d like to learn more about how Spirent can help protect receivers against current and emerging GNSS threats, or if you have any other questions about testing with Spirent, please do get in touch.

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Guy Buesnel
Guy Buesnel

CPhys, FRIN, Product Manager – GNSS Vulnerabilities

Guy has more than 16 years experience in working on Robust and Resilient Position Navigation and Timing, having started his career as a Systems Engineer involved in developing GPS Adaptive Antenna Systems for Military Users. Guy has been involved in GPS and GNSS Receiver System Design with the aim of designing a new generation of Rugged GNSS Receivers for use by Military and Commercial Aviation Users. Guy is a Chartered Physicist, a Member of the Institute of Physics and an Associate Fellow of the Royal Institute of Navigation