HOW TO COMBINE EXTREMELY LOW FREQUENCY (ELF) SIGNALS WITH GNSS FOR IMPROVED PNT

Last Updated: 23/11/2023 13:58     Created at: 21/11/2023 08:53

Final Presentation of NAVISP Project EL1 046 now available:

On Monday, November 13th, 2023, GMV NSL Ltd together with  Taylor Airey Limited and RHEATECH presented the results of the NAVISP EL1 046 project "Combining ELF signals with GNSS for improved PNT". 

Recognizing the need for a resilient PNT system alongside GNSS in critical scenarios has spurred awareness-raising actions (e.g., US and European radio navigation plans) and potential deployment initiatives (like the recent US Department of Transportation Request for Information). This renewed interest has focused on Extremely Low Frequency (ELF), Very Low Frequency (VLF), and Low Frequency (LF) systems, including enhanced Long Range Navigation (eLORAN), seen as promising candidates to support GNSS specifically, but not exclusively, for timing applications.

As safety-critical operations demand higher performance and trust beyond what a single-system approach can offer, a mix of PNT services is key—incorporating global, regional, and user-centric systems. Wireless networks can complement existing infrastructure, providing data dissemination and synchronization. For example, existing LF communication systems could be adapted for enabling regional PNT services, exploiting, thus, the available network of transmitters as well as the benefits of LF signals. Research has bolstered ELF, VLF, and LF-based PNT systems, enhancing signalling, broadcast formats, and authentication against tampering. However, understanding of these systems lags behind GNSS, requiring further R&D investments to fortify the PNT infrastructure.

This activity aimed therefore at developing an innovative, robust and reliable PNT concept based on ELF, VLF and LF techniques, able to complement GNSS-based services and to provide an alternative in the event of a GNSS outage or service disruption. The focus of the activity has been on selecting techniques based on specific use cases. These included, for instance, improving Enhanced PNT service (coverage and resilience) for handheld devices, developing Low-energy positioning, Local enhanced-low-energy positioning for underground transport and emergency services, and establishing Resilient PNT for airborne users. Key Performance Indicators (KPIs) were targeted to guide the selection process.  The goal was to identify their most effective metrics when operating independently and ultimately conclude with the development and a proof-of-concept. The project eventually validated the proposed PNT concept, called Omicron 2.0, by means of a proof-of-concept and benchmarked it against some key technology parameters.

At the end of the project, a comprehensive understanding of the potential of ELF, VLF and LF signals for radio navigation was achieved, which can  form the foundation for forthcoming R&D endeavours aimed at establishing dependable GNSS alternatives.

The project was carried out in the scope of NAVISP Element 1, which is dedicated to technology innovation of the European industry in the wide PNT sector.

More detailed information can be found in the slides of the Final Presentation.