User's Manual

D.Glossary
N72GNSSReferenceReceiverUserGuidePage66
communicationlinks.Itusesdatafromanetworkofreferencestationstoprovide
correctionstoeachroverthataremoreaccuratethancorrectionsfromasingle
basestation.
TostartusingVRScorrections,theroversendsitspositiontotheVRSserver.
The
VRSserverusesthereferencestationdatatomodelsystematicerrors(suchas
ionosphericnoise)attheroverposition.ItthensendsRTCMorCMRcorrection
messagesbacktotherover.
W AAS WideAreaAugmentationSystem.WAASwasestablishedbytheFederalAviation
Administration(FAA)forflightandapproach
navigationforcivilaviation.WAAS
improvestheaccuracyandavailability ofthebasicGPSsignalsoveritscoverage
area,whichincludesthecontinentalUnitedStatesandoutlyingpartsofCanada
andMexico.
TheWAASsystemprovidescorrectiondataforvisiblesatellites.Correctionsare
computedfromgroundstationobservationsandthenuploaded
totwo
geostationarysatellites.ThisdataisthenbroadcastontheL1frequency,andis
trackedusingachannelontheGPSreceiver,exactlylikeaGPSsatellite.
UseWAASwhenothercorrectionsourcesareunavailable,toobtaingreater
accuracythanautonomouspositions.FormoreinformationonWAAS,referto
the
FAAwebsiteathttp://gps.faa.gov.
TheEGNOSserviceistheEuropeanequivalentandMSASistheJapanese
equivalentofW AAS.
