Low Earth Orbit Positioning, Navigation and Timing (LEO-PNT)

Coherent Technical Services, Inc. (CTSi) and the University of Texas at Austin Radionavigation Lab (RNL) propose developing prototype modules that exploit Low-Earth Orbit (LEO) mega constellations to provide Position, Navigation, and Timing (PNT) data to mounted and dismounted troops. These prototypes will be compatible with the Mounted and Dismounted Assured PNT Systems (MAPS and DAPS, respectively) and exploit mega constellations like Starlink, OneWeb, Project Kuiper, and Xona Space Systems, and the recently announced. The initial prototype hardware will include Ku-band antennas and radio frequency (RF) front ends, a software defined radio (SDR), and navigation processing software that will enable operation with Starlink and OneWeb, while the fundamental approach is applicable to any other LEO constellation. During Phase I, the CTSi-RNL team developed a MAPS-to-DAPS architecture in which the MAPS platform would form differential corrections and broadcast them to DAPS units over a low bandwidth connection (<10 kbps). This architecture is enabled by our development of a blind signal identification method that we applied to fully characterize the Starlink signal structure. We identified key features shared by all satellites and channels, including the Primary and Secondary Synchronization Sequences (PSS and SSS), allowing our technique to be extended to many constellations providing a robust solution. During Phase II, the CTSi-RNL team will develop real-time software to acquire, track, and navigate with LEO signals in our SDR. We will develop hardware prototypes with antennas and RF bandwidths that are representative of both MAPS and DAPS units. We will demonstrate the ability to acquire, track, and navigate using signals from Starlink and OneWeb in both absolute (stand-alone) and relative (MAPS-to-DAPS) architectures. Work will be divided between CTSi and RNL with CTSi developing all real-time software and RNL capturing the RF samples used for software development and performing fundamental research on the limits of weak signal tracking, patterns of signal availability, satellite clock steering and timing, and absolute navigation algorithm development. Real-time software development will include all components to integrate LEO-PNT capabilities into our existing multi-GNSS SDR. The major functional components are acquisition planning, acquisition, tracking, antenna pointing/beam steering interface, signal tracking, and navigation processing. Our modular approach will ensure compatibility with future antenna developments, SDR and CPU upgrades, pntOS pluggable architectures, and additional LEO constellations as they become available. During Phase II, the CTSi-RNL team will fully describe the OneWeb signal as was done for Starlink under Phase I. This characterization will enable real-time tracking of two current constellations by the end of the period of performance.