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1、NotesforSignallingUnitLogfor(9M-MRO)FlightMH370ThissetofnotesandaccompanyingtablesisintendedtoprovideareadablesummaryofthedatacommunicationlogsfromtheInmarsatsatellitesystemprovidedtotheauthoritiesinconnectionwiththeongoinginvestigationandsearchandrescuea
2、ctivitiesrelatingtoMH370.AlltimesareinUTCThetablebelowisareadableformofthelogfilerecordedatthegroundearthstationforthecommunicationswiththeterminalonMH370from16:00tothelastHandshakeRequest(LogOnInterrogation)attemptat01:16UTCSomecolumnswhichcontainnoma
3、terialinformationhavebeenremovedfromthetablesbelowforreadabilityAnexampleofacompletemessageforasinglelogentry:FieldHeadings:Time,AESID,DPAESOwner,ChannelName,OceanRegion,GESID(octal),ChannelBearer,ChannelUnitID,ChannelType,SuperframeNumber,FrameNumber,Slo
4、tNumber,SUNumber,SUType,SUTypeCode,SUContents,QNumber,ReferenceNumber,AckControl,SDMFigure,CRCCorrect,MissedT-ChannelBurst,Broadcast,RxPower(dBm),C/No,FrequencyOffset(Hz),EstimatedBER,BurstTimingOffset(microseconds)Examplemessage:7/03/201416:42:04.408,352
5、00217,SITADP(3047),IOR-R1200-0-36ED,IOR,305,RxPrimary,4,R-ChannelRX,12184,,5,,0x62-AcknowledgeUserData(R-channel),62,1FD06275008FC57A4E00000000000000007F89,D,0,E,S31,Yes,No,No,-57.29,40.09,146,0,14920UnderstandingtheBurstTimingOffset(BTO)values:Theroundt
6、riptimeforamessageisacombinationof:1.Timefromthegroundstation→satellite→aircraft→satelliteїŐƌŽƵŶĚƐƚĂƟŽŶ2.Processingtimewithinthegroundstation,satelliteandaircraftterminal,whichareconstantTheBTOisavalue(inmicroseconds)relativetoaterminalatanominalfixedl
7、ocation.OnlyR-Channelmessagesareused.TheBTOthereforeallowsthedeterminationofthedistancebetweenthesatelliteandtheaircraft.Itdoesnotprovidetheactualaircraftlocation1UnderstandingtheBurstFrequencyOffset(BFO)values:Thetransmissionsignalpathfromtheaircraftha
8、stwocomponentsaffectedbyDopplershift;betweenthesatelliteandaircraft,andbetweenthesatelliteandgroundstationThefollowingneedtobeconsideredwhencomputingtheexpectedfrequencyoffset:oInmarsatClassicAeromobileterminalsare