Transponder Systems
Positions can be determined with any two measures of angle or distance. The introduction of radar in the 1930s provided a way to directly determine the distance to an object even at long distances. Navigation systems based on these concepts soon appeared, and remained in widespread use until recently. Today they are used primarily for aviation, although GPS has largely supplanted this role.
Read more about this topic: Radio Navigation
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“Not out of those, on whom systems of education have exhausted their culture, comes the helpful giant to destroy the old or to build the new, but out of unhandselled savage nature, out of terrible Druids and Berserkirs, come at last Alfred and Shakespeare.”
—Ralph Waldo Emerson (18031882)
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