Global Positioning System (GPS) based Position, Navigation, and Timing (PNT) systems are subject to interference that can hinder military operations. The deployment of large, Low Earth Orbit (LEO) satellite constellations presents an opportunity to maintain PNT in contested GPS environments. Emissions from these waveforms may be used in a non-cooperative Signals of Opportunity (SoOP) approach, whereby a PNT receiver passively receives these signals and deduces navigation information from them. Alternatively, a cooperative approach can be taken, where the receiver has knowledge of the signal structure, transmit time, and emitter state (i.e., position, velocity). These waveforms can be a vital source of PNT to US Navy platforms both by supplementing current PNT to enhance integrity and by maintaining PNT availability in Navigation Warfare (NAVWAR) or high interference environments. IS4S proposes to perform a concept study and initial performance assessment of LEO-based SoOP that will enhance Navy PNT availability and integrity. Both non-cooperative and cooperative SoOP will be considered in the study. In the case of cooperative SoOP, IS4S will investigate new waveforms or potential modifications to existing waveforms that will optimize PNT for Navy missions. Tradeoffs of each SoOP, including their impact on receivers/user equipment (i.e., receiver designs and navigation approaches), will be evaluated and used to recommend approaches for moving forward. Finally, IS4S will work with the Government to develop an integration strategy into Navy PNT systems, such as GPS-based Positioning, Navigation and Timing Service (GPNTS).
Benefit: Enhanced integrity and availability, GPS augmentation for operation in contested environments, and optimized use of LEO transmitters.
Keywords: LEO, LEO, Navigation, signals of opportunity, SOOP, PNT
