Editing Doppler radar (section)

==== Locus-based navigation ====
Location-based Doppler techniques were also used in the U.S. Navy's historical [[Transit (satellite)|Transit satellite navigation system]], with satellite transmitters and ground-based receivers, and are currently used in the civilian [[Argos system]], which uses satellite receivers and ground-based transmitters. In these cases, the ground stations are either stationary or slow-moving, and the Doppler offset being measured is caused by the relative motion between the ground station and the fast-moving satellite. The combination of Doppler offset and reception time can be used to generate a locus of locations that would have the measured offset at that intersects the Earth's surface at that moment: by combining this with other loci from measurements at other times, the true location of the ground station can be determined accurately.{{Citation needed|date=May 2017}}