The cost of disruption to Global Navigation Satellite Systems (GNSS) is more than just the loss of navigation but rather the cascading operational costs of a reduction in confidence in positioning.
This blog post explores the scale of this impact within the maritime industry, and the importance of improving GNSS resiliency.
Modern maritime operations depend heavily on GNSS systems; from open-sea routing, to precise harbour manoeuvres, to offshore drilling.
This reliance, however, is increasingly under threat with incidents of GNSS jamming and spoofing, once a military concern, now affecting all main shipping corridors as well as ports and other maritime operations.
In periods of interference, GNSS positioning degrades, becoming unreliable for navigation, and forcing the crew to compensate by reducing speed and increasing cross-checks using radar, visual watchkeeping and paper charts. The vessel may be able to continue on its track, but at a much slower rate, and that caution has a direct cost with vessel charter rates often running to $100k+/day.
Whilst crewed vessels can fall back to traditional navigation methods, this is not the case for those vessels that are uncrewed. Autonomous cargo ships, also known as Maritime Autonomous Surface Ships (MASS) may be operated from another location, or fully autonomous, and are heavily reliant on robust navigation systems providing continuous and reliable navigation data to the autonomous control systems.
Illustration of a MASS container vessel [Source: https://www.westpandi.com]
It’s not only GNSS degradation that creates risk. The more dangerous scenario is often spoofing that subtly manipulates position, and does so within the drift characteristics of the onboard inertial navigation system (INS) so as to go undetected - the vessel may appear to be following a safe track when it’s not, or may seem stable when it’s slowly drifting, and nearby traffic may appear in the wrong location or disappear from the chart entirely due to AIS errors.
Automatic Identity System (AIS) dependent on GNSS
With the risk that disruption could cause a cascade of vessel collisions totalling billions in damages, insurance premiums are doubling or tripling with underwriters limiting what they're willing to insure, prohibiting some routes and causing ships to reroute with substantial increases in voyage time and cost.
As vessels move from open water into coastal and port environments, the level of precision required increases significantly. Without it, port manoeuvres become significantly slower, impacting throughput, whilst a loss in confidence may prevent vessels from willingly entering or departing a port. Similarly, operations at container terminals involving automated cranes and yard management systems all stop unless centimetre-level accuracy can be guaranteed.
Any disruption to GNSS effectively creates a domino effect, escalating operational costs (for vessel operators and the port authority) and resulting in systemic supply chain disruption. It's perhaps no surprise that Gov.uk have estimated a 7-day GNSS outage to UK ports would cost a substantial ~£1.3 billion.
With GNSS interference being recorded in port vicinities worldwide, improving resiliency is key. Doing so not only improves safety, and more reliable port operations, but can also improve throughput and efficiency by enabling operation at night and in reduced visibility conditions.
High precision positioning is also core for many other maritime operations including offshore construction, dredging, cable laying and hydrographic survey, with costs quickly mounting ($200-400k/day per vessel) should GNSS fail or be degraded.
Options exist for positioning, including regional terrestrial systems (e.g., R-Mode in the Baltic region) and LEO-based PNT services such as Iridium STL. But none provide the accuracy and immediacy needed by most maritime operations, and delivered by GNSS.
High-end GNSS receivers can detect and filter out interference, but often struggle in heavily contested GNSS environments where the magnitude and sophistication of adversarial jamming can overwhelm them.
For instance: PRN denial of service (DoS) attacks in which the receiver is flooded with fake PRN codes that consume resources, or high-power attacks that saturate the receiver front-end (Automatic Gain Control hijacking), or sophisticated attacks with complex waveforms that defy efficient filtering.
A better approach is to suppress interference and jamming upstream at the antenna.
Controlled reception pattern antennas (CRPAs) do just that - dynamically altering their reception pattern to neutralise jammers and maximise signal strength from the GNSS satellites.
The technology was originally developed for the military as an electronic warfare countermeasure, but is now available to civil applications, and advocated by both the European Space Agency and Royal Institute of Navigation as an important measure to harden GNSS against interference and jamming attacks.
But not all CRPAs are suitable. GNSS signal linearity and phase stability are critical for GNSS antennas used in maritime navigation systems, and yet are often sacrificed in many CRPA designs in their pursuit of maximising anti-jamming performance.
Helix Geospace has taken a different approach.
Through its patented DielectriX antenna
technology, Helix has developed a CRPA
with very precise and consistent antenna
characteristics that enables it to be used
as a direct swap in maritime applications,
whilst also delivering military-grade
jamming suppression.
RAIM (and Advanced RAIM) is used in safety-critical aviation and maritime applications to assess GNSS signal integrity, and to some extent can be used to detect spoofing, but it was never designed for that purpose.
Spoofing is better handled by looking for anomalies in the GNSS signal, and/or authenticating the received GNSS messages using OSNMA, in the case of Galileo. But again, both these techniques rely on a clean GNSS signal being provided to the receiver and many CRPA designs fail to do this, either because they've introduced artefacts through the digital filtering they apply, or have had to regenerate the GNSS waveform post-processing. Either will wreak havoc downstream in the GNSS receiver - triggering false-positives in anti-spoofing algorithms, and failing OSNMA authentication due to outputting signals that are no longer bit-faithful to the original.
Not so in the case of Helix's CRPx. Through use of innovative RF design and minimising the level of signal processing needed, Helix have developed a CRPA that maintains GNSS signal linearity to avoid these issues, and is a perfect partner to anti-jamming/spoofing algorithms in the GNSS receiver for maximising end-end resilience.
GNSS disruption has become endemic in most if not all shipping corridors and poses a systemic risk to shipping, ports and many other maritime operations.
As GNSS becomes degraded or spoofed, confidence in positioning diminishes, operations slow and navigation becomes much more labour-intensive. This creates a domino effect on logistics and supply chains resulting in cascading operational costs and a reduction in productivity and throughput. With ~90% of world trade being carried by the international shipping industry, any such disruption has huge consequences.
The robustness of GNSS must be improved, but doing so is not straightforward given the stringent requirements of maritime navigation and high-precision positioning. And as of yet, there are no clear industry guidelines - IEC 61108 stipulates requirements for maritime equipment but is yet to address GNSS resiliency.
Best practise is to boost resilience at the antenna level using a CRPA and pair this with a GNSS receiver’s anti-jamming/spoofing algorithms to form a single resilient PNT system for feeding all navigation and safety systems on a vessel.
Helix Geospace develop CRPAs engineered specifically to meet these needs, as well as combining the technology with a high-performance INS to offer a resilient navigation system suitable for a range of maritime applications.
For more information on Helix Geospace's CRPx GNSS Anti-Jamming System and Resilient Navigation System, please do get in touch: info@helixgeospace.com.