Editing Radio navigation (section)

===Other hyperbolic systems===
Similar hyperbolic systems included the US global-wide [[VLF]]/[[Omega Navigation System]], and the similar [[Alpha (radio navigation)|Alpha]] deployed by the USSR. These systems determined pulse timing not by comparison of two signals, but by comparison of a single signal with a local [[atomic clock]]. The expensive-to-maintain Omega system was shut down in 1997 as the US military migrated to using [[GPS]]. Alpha is still in use.{{fact|date=July 2022}}