IS-GPS-705D (797936), страница 8
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In theevent that a particular message is not assigned (by the CS) a particular message type forbroadcast, the SV shall generate and broadcast the default message type in that message slot.Currently undefined and unused message types are reserved for future use.Block IIF SVs have the capability of storing at least 48 hours of CNAV navigation data, withcurrent memory margins, to provide CNAV positioning service without contact from the CS forthat period. GPS III SVs have the capability of providing up to 60 days of CNAV positioningservice without contact from the CS. The timeframe is defined by the CS.20.3.3 Message Content.Each message starts with an 8-bit preamble - 10001011, followed by a 6-bit PRN number ofthe transmitting SV, a 6-bit message type ID with a range of 0 (000000) to 63 (111111), andthe 17-bit message time of week (TOW) count.
When the value of the message TOW count ismultiplied by 6, it represents SV time in seconds at the start of the next 6-second message. An“alert” flag, when raised (bit 38 = “1”), indicates to the user that the signal URA componentsmay be worse than indicated in the associated message types and that he shall use at his ownrisk. For each default message (Message Type 0), bits 39 through 276 shall be alternating onesand zeros and the message shall contain a proper CRC parity block.41IS-GPS-705D24 Sep 2013911521PRN8BITS6BITSDIRECTION OF DATA FLOW FROM SV2 SECONDS100 BITS3852 5539666BITSMESSAGETOW COUNT*17 BITSMESSAGE TYPE ID"ALERT" FLAG - 1 BITPREAMBLEMSB FIRST7182toe∆A11 BITS19 MSBstopWN n13 BITS11 BITS5BITSL1 HEALTH – 1 BITL2 HEALTH – 1 BITL5 HEALTH – 1 BITURA ED INDEXDIRECTION OF DATA FLOW FROM SV100 BITS2 SECONDS101150133108∆A•A7 LSBs25 BITS∆nMSB FIRST173•∆n 0017 BITSM 0-n28 MSBs23 BITSDIRECTION OF DATA FLOW FROM SV100 BITS2 SECONDSMSB FIRST272201206277239ωnenM 0-n33 BITS5 LSBs33 BITSCRC24 BITSINTEGRITY STATUS FLAG – 1 BITL2C PHASING – 1 BITRESERVED – 3 BITS* MESSAGE TOW COUNT = 17 MSB OF ACTUAL TOW COUNT AT START OF NEXT 6 SECOND MESSAGEFigure 20-1.
Message type 10 - Ephemeris 142IS-GPS-705D24 Sep 20131159PRN6BITS8 BITS6BITSMSB FIRSTDIRECTION OF DATA FLOW FROM SV100 BITS2 SECONDS3850392183MESSAGETOW COUNT*toeΩ0-ni0-n17 BITS11 BITS33 BITS18 MSBsMESSAGE TYPE IDPREAMBLE"ALERT" FLAG - 1 BITMSB FIRSTDIRECTION OF DATA FLOW FROM SV100 BITS2 SECONDS101133116i0-n•∆Ω15 LSBs17 BITS•i0-n14816415 BITS180cis-ncic-ncrs-n16 BITS16 BITS21 MSBsMSB FIRSTDIRECTION OF DATA FLOW FROM SV100 BITS2 SECONDS201204228270249crc-ncus-ncuc-n24 BITS21 BITS21 BITScrs-n - 3 LSBs277CRC7 BITS24 BITSRESERVED* MESSAGE TOW COUNT = 17 MSB OF ACTUAL TOW COUNT AT START OF NEXT 6-SECOND MESSAGEFigure 20-2. Message type 11 - Ephemeris 243IS-GPS-705D24 Sep 2013192115PRN6BITS8 BITS6BITSMESSAGETOW COUNT*top17 BITS11 BITS5BITS"ALERT" FLAG - 1 BITtocaf0-n11 BITS26 BITSMSB FIRSTDIRECTION OF DATA FLOW FROM SV100 BITS2 SECONDS101128118af1-naf2-n17 LSBs10 BITS141154167α18 BITs209217α2225α38 BITS8 BITSβ08 BITS180193TGDISCL1C/AISCL2CISCL5I5ISCL5Q5α013 BITS13 BITS13 BITS13 BITS13 BITS8 BITSMSB FIRSTDIRECTION OF DATA FLOW FROM SV100 BITS2 SECONDS2019872URANED2 INDEX - 3 BITSURANED1 INDEX - 3 BITSaf1-n – 3 MSBsURANED0 INDEXMESSAGE TYPE IDPREAMBLEMSB FIRSTDIRECTION OF DATA FLOW FROM SV100 BITS2 SECONDS385055 58 6139233241β18 BITS257249β28 BITSβ3WNOP8 BITS8 BITS265277RESERVED12 BITSCRC24 BITS* MESSAGE TOW COUNT = 17 MSB OF ACTUAL TOW COUNT AT START OF NEXT 6-SECOND MESSAGEFigure 20-3.
Message type 30 - Clock, IONO & Group Delay44IS-GPS-705D24 Sep 2013192115PRN6BITS8 BITS6BITSMESSAGETOW COUNT*top17 BITS11 BITS5BITS"ALERT" FLAG - 1 BITtocaf0-n11 BITS26 BITSMSB FIRSTDIRECTION OF DATA FLOW FROM SV100 BITS2 SECONDS101128118141149af1-naf2-nWNa-ntoa17 LSBs10 BITS13 BITS8 BITS180Reduced AlmanacPacket 110 LSBs21121 MSBsMSB FIRST273 277242Reduced AlmanacPacket 3Reduced AlmanacPacket 431 BITS31 BITSReduced Almanac Packet 2Reduced AlmanacPacket 231 BITSDIRECTION OF DATA FLOW FROM SV100 BITS2 SECONDS2019872URANED2 INDEX - 3 BITSURANED1 INDEX - 3 BITSaf1-n – 3 MSBsURANED0 INDEXMESSAGE TYPE IDPREAMBLEMSB FIRSTDIRECTION OF DATA FLOW FROM SV100 BITS2 SECONDS385055 58 6139CRC4BITS24 BITSRESERVED* MESSAGE TOW COUNT = 17 MSB OF ACTUAL TOW COUNT AT START OF NEXT 6-SECOND MESSAGEFigure 20-4.
Message type 31 - Clock & Reduced Almanac45IS-GPS-705D24 Sep 2013192115PRN6BITS8 BITS6BITSMESSAGETOW COUNT*top17 BITS11 BITS5BITS"ALERT" FLAG - 1 BITtocaf0-n11 BITS26 BITSMSB FIRSTDIRECTION OF DATA FLOW FROM SV100 BITS2 SECONDS10117 LSBs144128118af1-naf2-ntEOP10 BITS16 BITS165180PM-X•PM-XPM-Y21 BITS15 BITS21 BITSMSB FIRSTDIRECTION OF DATA FLOW FROM SV100 BITS2 SECONDS20115 BITS266247216•PM-Y9872URANED2 INDEX - 3 BITSURANED1 INDEX - 3 BITSaf1-n – 3 MSBsURANED0 INDEXMESSAGE TYPE IDPREAMBLEMSB FIRSTDIRECTION OF DATA FLOW FROM SV100 BITS2 SECONDS385055 58 6139277∆UT1•∆UT1RESERVEDCRC31 BITS19 BITS11 BITS24 BITS* MESSAGE TOW COUNT = 17 MSB OF ACTUAL TOW COUNT AT START OF NEXT 6-SECOND MESSAGEFigure 20-5. Message type 32 - Clock & EOP46IS-GPS-705D24 Sep 2013192115PRN6BITS8 BITS6BITSMESSAGETOW COUNT*top17 BITS11 BITS5BITSURANED0INDEX"ALERT" FLAG - 1 BITtocaf0-n11 BITS26 BITSMSB FIRSTDIRECTION OF DATA FLOW FROM SV100 BITS2 SECONDS1011281181449872URANED2 INDEX - 3 BITSURANED1 INDEX - 3 BITSaf1-n – 3 MSBsMESSAGE TYPE IDPREAMBLEMSB FIRSTDIRECTION OF DATA FLOW FROM SV100 BITS2 SECONDS385055 58 6139157164172188af1-naf2-nA0-nA1-nA2-n∆tLStotWNot17 LSBs10 BITS16 BITS13 BITS7 BITS8 BITS16 BITS13 BITSDIRECTION OF DATA FLOW FROM SV100 BITS2 SECONDSWNLSF13 BITS277226214 218201MSB FIRST∆tLSF4BITS 8 BITSDNRESERVEDCRC51 BITS24 BITS* MESSAGE TOW COUNT = 17 MSB OF ACTUAL TOW COUNT AT START OF NEXT 6-SECOND MESSAGEFigure 20-6.
Message type 33 - Clock & UTC47IS-GPS-705D24 Sep 2013192115PRN6BITS8 BITS6BITSMESSAGETOW COUNT*top17 BITS11 BITS"ALERT" FLAG - 1 BIT101128118af1-naf2-n17 LSBs10 BITS5BITS9872tocaf0-n11 BITS26 BITSURANED2 INDEX - 3 BITSURANED1 INDEX - 3 BITSaf1-n – 3 MSBsURANED0 INDEXMESSAGE TYPE IDPREAMBLEMSB FIRSTDIRECTION OF DATA FLOW FROM SV100 BITS2 SECONDS385055 58 6139DIRECTION OF DATA FLOW FROM SV100 BITS2 SECONDS150139151top-D11 BITSMSB FIRST185tODCDCEDC11 BITS34 BITS16 MSBsDC DATA TYPE – 1 BITDIRECTION OF DATA FLOW FROM SV100 BITS2 SECONDSMSB FIRST277201EDCCRC76 LSBs24 BITS* MESSAGE TOW COUNT = 17 MSB OF ACTUAL TOW COUNT AT START OF NEXT 6-SECOND MESSAGECDC = Clock Differential CorrectionEDC = Ephemeris Differential CorrectionFigure 20-7. Message type 34 - Clock & Differential Correction48IS-GPS-705D24 Sep 2013192115PRN6BITS8 BITS6BITSMESSAGETOW COUNT*top17 BITS11 BITS5BITS"ALERT" FLAG - 1 BITtocaf0-n11 BITS26 BITSDIRECTION OF DATA FLOW FROM SV100 BITS2 SECONDS1011281189872URANED2 INDEX - 3 BITSURANED1 INDEX - 3 BITSaf1-n – 3 MSBsURANED0 INDEXMESSAGE TYPE IDPREAMBLEMSB FIRSTDIRECTION OF DATA FLOW FROM SV100 BITS2 SECONDS385055 58 6139144157 160MSB FIRST189176af1-naf2-ntGGTOWNGGTOA0GGTO17 LSBs10 BITS16 BITS13 BITS16 BITSA1GGTO13 BITS7 BITS 5 BITSRESERVEDGNSS ID – 3 BITSDIRECTION OF DATA FLOW FROM SV100 BITS2 SECONDS196A2GGTOMSB FIRST277201RESERVEDCRC76 BITS24 BITS* MESSAGE TOW COUNT = 17 MSB OF ACTUAL TOW COUNT AT START OF NEXT 6-SECOND MESSAGEFigure 20-8.
Message type 35 - Clock & GGTO49IS-GPS-705D24 Sep 2013192115PRN6BITS8 BITS6BITSMESSAGETOW COUNT*top17 BITS11 BITS5BITS"ALERT" FLAG - 1 BITtocaf0-n11 BITS26 BITSMSB FIRSTDIRECTION OF DATA FLOW FROM SV100 BITS2 SECONDS1019872URANED2 INDEX - 3 BITSURANED1 INDEX - 3 BITSaf1-n – 3 MSBsURANED0 INDEXMESSAGE TYPE IDPREAMBLEMSB FIRSTDIRECTION OF DATA FLOW FROM SV100 BITS2 SECONDS385055 58 6139128118af1-naf2-n17 LSBs10 BITSTEXT MESSAGE (18 8-BIT CHAR)73 MSBsMSB FIRSTDIRECTION OF DATA FLOW FROM SV100 BITS2 SECONDS276277272201TEXT MESSAGE (18 8-BIT CHAR)CRC4BITS71 LSBsTEXT PAGE24 BITSRESERVED – 1 BIT* MESSAGE TOW COUNT = 17 MSBs OF ACTUAL TOW COUNT AT START OF NEXT 6-SECOND MESSAGEFigure 20-9. Message type 36 - Clock & Text50IS-GPS-705D24 Sep 2013192115PRN6BITS8 BITS6BITSMESSAGETOW COUNT*top17 BITS11 BITS5BITS"ALERT" FLAG - 1 BITtocaf0-n11 BITS26 BITSMSB FIRSTDIRECTION OF DATA FLOW FROM SV100 BITS2 SECONDS1011281189872URANED2 INDEX - 3 BITSURANED1 INDEX - 3 BITSaf1-n – 3 MSBsURANED0 INDEXMESSAGE TYPE IDPREAMBLEMSB FIRSTDIRECTION OF DATA FLOW FROM SV100 BITS2 SECONDS385055 58 6139141af1-naf2-nWNa-n17 LSBs10 BITS13 BITStoa149155 15818011 BITS11 BITS191•ΩA11 BITS10 MSBsδiePRNa8 BITS 6 BITS169L1 HEALTH – 1 BITL2 HEALTH – 1 BITL5 HEALTH – 1 BITMSB FIRSTDIRECTION OF DATA FLOW FROM SV100 BITS2 SECONDS201A7 LSBs240224208256277267Ω0ωM0af0af1CRC16 BITS16 BITS16 BITS11 BITS10 BITS24 BITS* MESSAGE TOW COUNT = 17 MSBs OF ACTUAL TOW COUNT AT START OF NEXT 6-SECOND MESSAGEFigure 20-10.
Message Type 37 - Clock & Midi Almanac51IS-GPS-705D24 Sep 20131159PRN8 BITS6BITS6BITS21MESSAGETOW COUNT*13 BITS17 BITS91toaReduced AlmanacPacket 18 BITS31 BITSWNa-n10 MSBsReduced Almanac Packet 2MESSAGE TYPE IDPREAMBLEMSB FIRSTDIRECTION OF DATA FLOW FROM SV100 BITS2 SECONDS38605239"ALERT" FLAG - 1 BITDIRECTION OF DATA FLOW FROM SV100 BITS2 SECONDS122101Reduced AlmanacPacket 221 LSBs153184Reduced AlmanacPacket 4Reduced AlmanacPacket 3215Reduced AlmanacPacket 531 BITS31 BITSDIRECTION OF DATA FLOW FROM SV100 BITS2 SECONDS201MSB FIRST17 MSBsMSB FIRST277246Reduced AlmanacPacket 5Reduced AlmanacPacket 6Reduced AlmanacPacket 7CRC14 LSBs31 BITS31 BITS24 BITS* MESSAGE TOW COUNT = 17 MSBs OF ACTUAL TOW COUNT AT START OF NEXT 6-SECOND MESSAGEFigure 20-11. Message type 12 - Reduced Almanac52IS-GPS-705D24 Sep 2013121159MESSAGETOW COUNT*PRN8 BITS6BITS6BITStop-DCDC11 BITS11 BITS17 BITS9697tODMESSAGE TYPE IDPREAMBLEMSB FIRSTDIRECTION OF DATA FLOW FROM SV100 BITS2 SECONDS613850396234 BITSDC DATA TYPE – 1 BITDC DATA TYPE – 1 BITCDC - 4 MSBs"ALERT" FLAG - 1 BITMSB FIRSTDIRECTION OF DATA FLOW FROM SV100 BITS2 SECONDS131166132167101CDCCDCCDC30 LSBs34 BITS34 BITSDC DATA TYPE – 1 BITDC DATA TYPE – 1 BITDIRECTION OF DATA FLOW FROM SV100 BITS2 SECONDS236237201202MSB FIRST271277CDCCDC34 BITS34 BITS6BITSCRC24 BITSDC DATA TYPE – 1 BITDC DATA TYPE – 1 BITRESERVED* MESSAGE TOW COUNT = 17 MSBs OF ACTUAL TOW COUNT AT START OF NEXT 6-SECOND MESSAGECDC = Clock Differential CorrectionFigure 20-12.
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