An Introduction to High-Altitude Space Use of GNSS (For Timing People)

The Global Positioning System (GPS) and other global navigation satellite systems (GNSS) are used routinely in low Earth orbit for a variety of applications, including spacecraft navigation, radio occultation remote sensing, and time synchronization. High-altitude use of these systems, near to and above the constellations themselves, are an emerging operational capability. This talk provides an overview of such high-altitude space use of GNSS, specifically related to spacecraft navigation and time synchronization and estimation for members of the Civil GPS Service Interface Committee (CGSIC) Timing Subcommittee.