2023學(xué)年完整公開課版WORKINGPrincipleofGPS(2022version)

物流信息技術(shù)與應(yīng)用LogisticsinformationTechnologyandapplication4.2.3GPS工作原理4.2.3WorkingprincipleofGPS衛(wèi)星定位的基本原理Thebasicprinciplesofsatellitepositioning首先假定衛(wèi)星的位置為已知，而又能準(zhǔn)確測定某地點(diǎn)A至衛(wèi)星之間的距離，那么A點(diǎn)一定是位于以衛(wèi)星為中心，所測得距離為半徑的圓球面上。

GPSworkingsatellitesandtheirconstellationsarecomposedof21workingsatelliteswithanaltitudeofabout20,000kmand3standbysatellitesinorbit,whicharereferredtoas(21+3)GPSconstellations.另外，還可測得與第三個衛(wèi)星的距離，通過3個定位球面就可以確定A點(diǎn)在地球上的空間位置。如果要定位空中位置（如飛機(jī)），還可通過第4顆衛(wèi)星。Inaddition,thedistancewiththethirdsatellitecanbemeasured,andthespatialpositionofpointAontheearthcanbedeterminedthroughthreepositioningspheres.Ifyouwanttolocateanairborneposition(suchasanaircraft),youcanalsouseafourthsatellite.進(jìn)一步，又測得點(diǎn)A至另一衛(wèi)星的距離，則A點(diǎn)一定處在前后兩個圓球面相交的圓環(huán)上。Furthermore,thedistancebetweenpointAandanothersatelliteismeasured,sopointAmustbeonthecirclewherethetwosphericalspheresintersect.GPS的定位原理ThepositioningprincipleofGPS在太空中如果只有一顆衛(wèi)星，并知道某被觀測物與這顆衛(wèi)星的距離，那么被觀測物肯定在以衛(wèi)星為中心，以被觀測物與衛(wèi)星距離為半徑的球面上，這雖然界定了一個范圍，但球面可以有無數(shù)個點(diǎn)，無法確定它的準(zhǔn)確位置。Ifthereisonlyonesatelliteinspaceandthedistancebetweentheobservedobjectandthesatelliteisknown,thentheobservedobjectmustbeonthespherewiththesatelliteasthecenterandthedistancebetweentheobservedobjectandthesatelliteastheradius.Althoughthisdefinesarange,thespherecanhavecountlesspoints,soitisimpossibletodetermineitsexactposition.GPS的定位原理ThepositioningprincipleofGPS如果有第二顆衛(wèi)星，且知道被觀測物與第二顆衛(wèi)星的距離，同理，被觀測物也在以第二顆衛(wèi)星為中心，以與第二顆衛(wèi)星的距離為半徑的球面上，若滿足上述兩個條件的被觀測物一定在兩個球面的交界線上，即一個圓周線上。Ifthereisasecondsatelliteandthedistancebetweentheobservedobjectandthesecondsatelliteisknown,similarly,theobservedobjectisalsoonaspherecenteredonthesecondsatelliteandwiththedistancefromthesecondsatelliteasitsradius.Iftheobservedobjectsatisfiestheabovetwoconditions,itmustbeontheboundaryofthetwospheres,namelyacircumferentialline.GPS的定位原理ThepositioningprincipleofGPS如果有第三顆衛(wèi)星，并知道被觀測物與它的距離，那么被觀測物一定在圓周線與第三顆衛(wèi)星為中心的球面的交點(diǎn)上，這時(shí)，球面與圓周線相交于兩點(diǎn)。Ifthereisathirdmoonandtheobservedobjectisknownatitsdistance,thentheobservedobjectmustbeattheintersectionofthecircumferenceandthespherecenteredonthethirdsatellite.Inthiscase,thesphereandthecircum