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ArkEdge Space Inc. has completed a study commissioned by the Japan Aerospace Exploration Agency (JAXA) on “Elemental Technologies and Systems for a Dedicated, GNSS-Independent LEO-PNT Satellite System.”
Positioning, navigation and timing derived from GNSS is increasingly subject to interruption and interference, both through environmental and security challenges. Finding methods to protect PNT information against such interference is of paramount importance for governments and commercial actors alike.
The ArkEdge/JAXA project addressed such challenges by examining and categorizing the necessary elemental technologies — signal design, receiver technology, ground infrastructure, satellite sensors, and the overall system architecture — required to realize a LEO-PNT system capable of providing PNT without reliance on traditional GNSS.
The study’s focus included achieving satellite orbit determination and time synchronization without GNSS, one of the key challenges facing alternative PNT providers. It explored a new architecture for onboard time determination that avoids the need for large atomic clocks. Instead of onboard clocks, the system transmits precise timing information from combinations of ground-based reference clocks, pseudolites and inter-satellite optical links to disseminate information and enable on-orbit ODTS.
The study considered diverse frequencies to strengthen anti-jamming measures. It also looked at novel signal design, receivers, encryption and signal authentication methods, and their suitability for LEO-PNT satellites. Results of the study will contribute to the next stage of development for a GNSS-independent LEO-PNT concept.
“This study is critical to advancing our understanding of Japan’s future relationship with PNT,” said ArkEdge Space Chief Strategy Officer Tomoaki Yasuda. “Across the world, users are facing denial of GNSS services, and that can have critical consequences for sectors including the economy, transport and emergency services, among others. We look forward to progressing the GNSS-independent LEO-PNT concept with the support of our partners.”
“Due to the prevalence of GNSS interference, alternative PNT systems are becoming increasingly important to protect users and assets such as critical national infrastructure,” said Masaya Murata, JAXA. “Following the successful conclusion of this GNSS-independent LEO-PNT study with ArkEdge Space, our investigation into a robust and resilient LEO-PNT system continues. We are also emphasizing international cooperation with other LEO-PNT providers to maximize users’ PNT experience and continue to engage in collaborative discussions.”
