The Need

Reliable positioning, navigation, and timing (PNT) in GNSS‑denied or disrupted environments remains a critical challenge for defense, transportation, and autonomous systems. While low Earth orbit (LEO) communications satellites offer powerful signals and rapid geometry changes, they are typically non‑cooperative and do not broadcast precise ephemerides. Publicly available orbit data can be inaccurate by kilometers, rendering conventional navigation filters ineffective without infrastructure support or prior GNSS initialization. There is a strong unmet need for standalone navigation technologies that can exploit existing LEO constellations despite large orbit and clock uncertainties.

The Technology

OSU engineers have developed a signal‑processing and estimation framework that enables a standalone receiver to navigate using non‑cooperative LEO satellite signals with poorly known ephemerides. The framework jointly estimates the receiver’s position and the satellites’ orbit and clock errors directly from Doppler and/or ranging measurements, without GNSS aiding or ground infrastructure. By combining online ephemeris error correction with advanced nonlinear state estimation, the approach converts inaccurate public orbit data into navigation‑grade information in real time, enabling rapid convergence from kilometer‑level initial uncertainty to tens‑of‑meters accuracy.

Commercial Applications

• GNSS-denied or degraded navigation for autonomous vehicles and UAVs
• Resilient PNT solutions for defense and public safety users

Benefits/Advantages

• No cooperation required: Operates with existing LEO communication satellites and public orbit data.
• Infrastructure‑free: Eliminates reliance on GNSS availability, base stations, or prior calibration.
• High accuracy from poor priors: Demonstrated orders‑of‑magnitude improvement over conventional filters.
• Constellation‑agnostic: Applicable across multiple LEO constellations and signal types.