Title: navigation  | National Geographic Society
Headings: navigation
navigation
Encyclopedic Entry
Vocabulary

Content: Radio Navigation
Radio navigation is similar to celestial navigation, except it replaces objects in the sky with radio waves being broadcast. The navigator can tune into a radio station and use an antenna to find the direction of the broadcasting radio antenna. Position can be determined by measuring the time it takes to receive radio signals from the stations of known locations on the ground or aboard satellites. Radar is a type of radio navigation. It originally stood for Radio Detection And Ranging. Radar is a system that measures the time it takes to bounce electromagnetic waves off an object and back to a receiver. The waves that reflect back to the receiver indicate the object's distance. GPS
GPS, or global positioning system, is a satellite -based navigation system. While the GPS system is funded and controlled by the U.S. governments Department of Defense, anyone with a GPS receiver can use it. The earliest GPS system was launched between 1978 and 1985 with 11 satellites.