The Need

Positioning, navigation, and timing (PNT) systems increasingly seek alternatives or complements to GNSS due to vulnerability to interference, jamming, and limited performance in challenged environments. While low Earth orbit (LEO) communication satellites offer strong signals and favorable geometry, exploiting them for PNT typically requires prior ephemeris knowledge, cooperative signals, or hardware modifications. Existing opportunistic approaches relying on timing measurements are becoming less reliable as modern broadband satellite waveforms introduce signal artifacts that degrade traditional ranging methods.

The Technology

OSU engineers have developed a novel framework that enables passive sensing, tracking, and ephemeris estimation of LEO satellites by extracting direction-of-arrival (DOA) information from received signal strength measurements. Using commercially available, communication-optimized antenna terminals, the approach operates in a closed-loop manner and requires no prior satellite ephemeris information beyond approximate altitude. The framework can be combined with Doppler-based measurements to further refine satellite state estimates, enabling accurate tracking and downstream positioning without modifying satellite signals or receiver hardware.

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 passively on existing commercial LEO signals of opportunity
• Minimal prior knowledge: Does not require satellite ephemerides or signal redesign
• Hardware-efficient: Uses unmodified, commercially deployed phased-array SATCOM terminals
• Future-proof PNT: DOA measurements remain robust even as communication waveforms evolve