GPS & Satellite Navigation
While the principles of operation of GPS are simple and quite ancient, the technologies required for the realization of the system didn’t become available until the last third of the 20th century.
This course stresses concepts from astrodynamics, geodesy, and timekeeping and their roles in the technologies of global navigation satellite systems: maintaining spacecraft in stable orbits and knowing their positions with meter-level accuracy; definition and realization of precise and consistent global coordinate frames in which to express the positions of the satellites and GPS users; and development of ultra-stable clocks that can keep time over days with an accuracy of nanoseconds. The students obtain and record raw GPS measurements using a simple receiver and analyze the measurements to calculate their positions. We discuss also GPS-like systems now in various stages of development in Russia, Europe, and China.
- Principles of satellite navigation
- Navigation before GPS: Longitude and time, triangulation and trilateration, radio-navigation (Loran, Omega, Transit)
- Origins of GPS
- Time references and GPS Time
- Global coordinate frames: WGS 84
- GPS satellite constellation and orbits
- GPS signals: spread spectrum signals and code division multiple access
- GPS measurements (pseudorange and carrier phase) and sources of error therein
- Estimation of position, velocity, and time (PVT) from pseudorange measurements
- GPS receiver design: signal acquisition & tracking loops
- Mitigation of measurement errors: differential GPS
- Centimeter-level positioning with carrier phase measurements