GPS
Compiled by Mark Francek (more info) at Carleton College (more info) (SERC) and Central Michigan University (more info)
Find animations relating to how GPS signals are acquired.
Orbiting Earth, Exploring Earth (more info) This Flash animation contrasts the geostationary versus polar orbits for satellites. For a geostationary orbit, the satellite remains directly above a fixed point at all times; in time with the earth's rotation, the satellite circles the earth once every 24 hours, continually viewing the same part of Earth. For the polar orbit, the satellite circles over both poles in a constant plane while earth rotates beneath. Earth's rotation exposes different parts of the surface on each orbit. The animation is useful for a discussion on how remote sensing imagery and Global Positioning Systems (GPS) signals are derived. The animation can be paused and rewound to stress important points.
Global Positioning Systems, Wiley ( This site may be offline. ) View an animated Flash slide show explaining how GPS works. GPS operates because of three interconnected segments: the satellite, ground control, and user segments. This animation focuses on the satellite and user segments, briefly touching upon how the satellite signal is processed to produce positional values in hand-held GPS units. Note that the accuracy claimed for handheld GPS units—100 m—is now routinely exceeded. With the "turning off" of selective availability, today's GPS handheld units usually get accuracies of better than 10 meters. Note that the video loads slowly.
GPS, NASA (more info) A short QuickTime format video combining live video, audio, and animation to relate how the GPS signal is calculated. The movie lists what useful measurements GPS units can record like latitude, longitude, speed, distance and time to destination. The video can be paused and rewound to stress important points.
