A GNSS-Synchronized Satellite Navigation Payload for LEO PNT

Abstract

Efforts on positioning, navigation and timing (PNT) services from low Earth orbit (LEO) have significantly increased over the last years not only within research institutions, but also by space agencies and industry. Satellite mega-constellations in LEO as well as the increasing need for more resilient and secure alternatives to GNSS are major motivations for research and development in LEO PNT. Various concepts have emerged, which aim to either enhance GNSS or offer independent PNT alternatives. We present the concept and current development status of a prototypical satellite navigation payload for a LEO overlay system. Being strictly synchronized to existing GNSS constellations, the payload is designed to augment GNSS by means of additional signals. No dedicated ground segment is needed, while the requirements for space infrastructure are kept at a minimum. The payload is intended to have a small footprint and aims to improve cost-efficiency and scalability for large satellite constellations. Results from previous studies have shown that a real-time on-board navigation system can achieve a 11 cm 3D orbit root-mean-square (RMS) error as well as a timing error of less than 1 ns, which translates into a signal-in-space ranging error better than 30 cm.