Optical Astrometry and the Global Positioning System

Global astrometry with OSI

— The Orbiting Stellar Interferometer is a proposed space-based interferometer which makes very accurate wide-angle astrometric measurements on several thousand stars. As opposed to Hipparcos, OSI does not have a “basic angle” between two separate field-of-views but three separate interferometers and a highly accurate metrology system. The questions addressed in this paper are whether it is pos...

Global Positioning System (A Review)

Accurate measurement of physical activity is a pre-requisite to monitor population physical activity levels and design effective interventions. Global Positioning System (GPS) technology offers potential to improve the measurement of physical activity. This paper 1) reviews the extant literature on the application of GPS to monitor human movement, with a particular emphasis on free-living physi...

NAVSTAR Global Positioning System Surveying

Relativity in the Global Positioning System

The Global Positioning System (GPS) uses accurate, stable atomic clocks in satellites and on the ground to provide world-wide position and time determination. These clocks have gravitational and motional frequency shifts which are so large that, without carefully accounting for numerous relativistic effects, the system would not work. This paper discusses the conceptual basis, founded on specia...

Relativistic Effects in the Global Positioning System

The Global Positioning System (GPS) provides a superb opportunity to introduce relativity concepts to undergraduate students, including non-physics majors. Familiarity with the numerous applications of GPS motivates students to understand relativity. A few fundamental principles need to be introduced, including the postulates of special relativity and the universality of free fall. Then a serie...