Trimble R10 - Page 140

TrimbleR10ReceiverWebHelp
antennas,plugintoaPCCardslotorintotheUSBportofthecomputerand
areavailableforavarietyofwirelessdataservicessuchasGPRS.
CMR/CMR+
CompactMeasurementRecord.Areal‐timemessageformatdevelopedby
TrimbleforbroadcastingcorrectionstootherTrimblereceivers.CMRisa
moreefficientalternativeto
RTCM.
CMRx
Areal‐timemessageformatdevelopedbyTrimblefortransmittingmore
satellitecorrectionsresultingfrommoresatellitesignals,moreconstellations,
andmoresatellites.Itscompactnessmeansmorerepeaterscanbeusedona
site.
Compass
TheBeiDouNavigationSatelliteSystem(Compass)isaChinesesatellite
navigationsystem.
ThefirstBeiDousystem(knownasBeiDou‐1),consistsofthreesatellitesand
haslimitedcoverageandapplications.Ithasbeenofferingnavigation
servicesmainlyforcustomersinChinaandfromneighboringregionssince
2000.
Thesecondgenerationofthesystem(knownasCompassorBeiDou‐2)
consistsof35satellites.ItbecameoperationalwithcoverageofChinain
December2011with10satellitesinuse.Itisplannedtoofferservicesto
customersinAsia‐Pacificregionby2012andtheglobalsystemshouldbe

finishedby2020.
covariance
Astatisticalmeasureofthevarianceoftworandomvariablesthatare
observedormeasuredinthesamemeantimeperiod.Thismeasureisequal
totheproductofthedeviationsofcorrespondingvaluesofthetwovariables
fromtheirrespectivemeans.
datum
Alsocalled
geodeticdatum.Amathematicalmodeldesignedtobestfitthe
geoid,definedbytherelationshipbetweenanellipsoidand,apointonthe
topographicsurface,establishedastheoriginofthedatum.Worldgeodetic
datumsaretypicallydefinedbythesizeandshapeofan
ellipsoidandthe
relationshipbetweenthecenteroftheellipsoidandthecenteroftheearth.
Becausetheearthisnotaperfectellipsoid,anysingledatumwillprovidea
bettermodelinsomelocationsthaninothers.Therefore,variousdatums
havebeenestablishedtosuitparticularregions.
Forexample,maps
inEuropeareoftenbasedontheEuropeandatumof
1950(ED‐50).MapsintheUnitedStatesareoftenbasedontheNorth
Americandatumof1927(NAD‐27)or1983(NAD‐83).
AllGPScoordinatesarebasedonthe
WGS‐84datumsurface.
deepdischarge
Withdrawalofallelectricalenergytotheend‐pointvoltagebeforethecellor
batteryisrecharged.
DGPS
See
real‐timedifferentialGPS.
differentialcorrection
DifferentialcorrectionistheprocessofcorrectingGNSSdatacollectedona