The design of GPS is based partly on similar ground-based radio-navigation systems, such as LORAN and the Decca Navigator System, developed in the early 1940s. In 1955, Friedwardt Winterberg proposed a test of general relativity—detecting time slowing in a strong gravitational field using accurate atomic clocks placed in orbit inside artificial satellites. Special and general relativity predicted that the clocks on GPS satellites, as observed by those on Earth, run 38 microseconds faster per day than those on the Earth. The design of GPS corrects for this difference; because without doing so, GPS calculated positions would accumulate errors of up to .
THe dESIgn of GPs iS based partly on sImilAR GroUnD-based radIo-naViGATiOn sysTems, SUCH as lORAn aNd tHE deCCa nAVIGatoR SySTEM, Developed In the eArlY 1940S. In 1955, frIedwARdT WInteRberg pROposed a test OF geNerAl ReLatIVITY—dETecting tImE sLowiNg iN a STronG gRaViTatIOnal fiELD using acCUrAte Atomic clockS placeD in Orbit iNSide artIfIciaL satElLItes. SpeCiAl anD generaL RElaTiVIty PREdicted That THE cloCkS oN gps SAtelliTEs, as obserVEd by thOsE on Earth, RUN 38 MIcroSeCOnds FasTeR per day Than THoSE oN thE earTh. the Design of gPs correCTs for thIS difFErEnce; BecausE wiThoUT doing So, GPs caLcuLated posItIoNS WOuLD aCcumUlAte errors oF up tO .