On June 7th, Satelles will present at Session B4: “Data Authentication/Alternate Sources of Timing for Critical Infrastructure Applications Independent Test Results from a LEO-Satellite-Based Secure Timing Solution.”   Much recent attention has been given to the potential use of Low Earth Orbit (LEO) satellites to augment GPS solutions by providing an independent signal that is highly resilient and cryptographically secure. A combination of GPS and LEO satellites shows promise as part of an integrated solution for assured position, navigation, and time. This paper describes an independent set of tests performed by SRNL to evaluate over-the-air performance of one such system based on the Iridium LEO constellation. Test results are presented and the applicability of the technology for certain categories of con ops involving GPS back-up and augmentation are explored.

The Iridium constellation consists of 66 LEO satellites which are primarily used for global communications. An Iridium-based time and location solution is now available based on specially structured time and location signal bursts which, due to their high RF power and signal coding gain, are able to penetrate into difficult signal environments. Like GPS, these signal bursts are specifically designed to enable time and location measurements by a receiver. In addition, the signal bursts contain unpredictable content which uniquely allows a user to validate the source of the signal, and potentially allows a third party to validate the location of the user, both with very high integrity.

The presentation will include a description of the system, including the ground segment, space segment, and user equipment. Performance of the system is measured experimentally in multiple operational configurations, including high attenuation environments. These results are presented, and the suitability of a resilient and secure LEO-based time and location solution as an augmentation or back-up to GPS is considered.  Link to conference website