ICD Beidou (version 2.0) (797932), страница 7
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1Pre Rev FraID SOWSOW Rev PnumiaaetoaΩΩ37~6010A P A P0 P0iPPP512bits 1bit 7bits 2bits22bits11bits 11bits13bits 8bits22bits2bits 17bits 3bits95~100 11bits 4bits 3bits 8bits8MSBsFig 5-18-2912LSBs2MSBs22LSBs22MSBs2LSBs3MSBs13LSBs2111bit1MSB241ω271ωM0M0 RevPPPP20bits 2bits16bits 6bits18bits 4bits16LSBs6MSBs18LSBs4MSBs20LSBsBits allocation of pages 37 through 60 and pages 95 through 100 of subframe 5 in format D264BDS-SIS-ICD-2.02013-12 2013 China Satellite Navigation OfficeDirection of data flowMSBMSB firstLSBSubframe 5 (300 bits) bits allocationWord 1Subframe PageNo.No.5127 316191121151181211Pre Rev FraID SOWSOW Rev Pnum RevRevRev A0GPS A1GPSA1GPS A0GalA0Gal A1GalA0GLO A1GLOA1GLO Rev 24bits Parity for 3101 11bits 4bits 3bits 8bits P 12bits 1bit 7bits 2bits P 22bits P 6bits 14bits 2bits P 14bits 8bits P 6bits 16bits P 14bits 8bits P 8bits 58bitswords8MSBs12LSBs2MSBsFig 5-18-3014LSBs8MSBs6LSBs8MSBs8LSBsBits allocation of page 101 of subframe 5 in format D2Direction of data flowMSBMSB firstLSBSubframe 5 (300 bits) bits allocationWord 1Subframe PageNo.No.5127 3161Pre Rev FraID SOWSOW Rev Pnum ΔtLSΔtLS102PP11bits 4bits 3bits 8bits12bits 1bit 7bits 2bits6bits8MSBs12LSBs2MSBsFig 5-18-3191ΔtLSF8bitsWNLSF8bits6LSBsPA0UTC22bits22MSBs121PA0UTC10bits10LSBs151A1UTC12bits12MSBsA1UTC12bitsPDN Rev8bits 90bits40bits Parity for 5words12LSBsBits allocation of page 102 of subframe 5 in format D265BDS-SIS-ICD-2.02013-12 2013 China Satellite Navigation OfficeDirection of data flowMSBLSBSubframe 5 (300 bits) bits allocationWord 1Subframe PageNo.No.
127 3114~34Pre Rev FraID SOWSOW RevP74~94511bits 4bits 3bits 8bits12bits 1bit103~1208MSBsFig 5-18-32MSB firstPnum7bitsRev178bits72bits Parity for 9 words12LSBsBits allocation of reserved pages 14 through 34, pages 74 through 94 and pages103 through 120 of subframe 5 in format D266BDS-SIS-ICD-2.02013-12 2013 China Satellite Navigation Office5.3.3 D2 NAV Message Content and AlgorithmD2 NAV message contains basic NAV information and augmentationservice information.5.3.3.1 Basic NAV InformationD2 NAV message contains all the basic NAV information as follows:Fundamental NAV information of the broadcasting satellite: Preamble (Pre) Subframe identification (FraID) Seconds of week (SOW) Week number (WN) User range accuracy index (URAI) Autonomous satellite health flag (SatHl) Ionospheric delay model parameters (αn, βn, n=0~3) Equipment group delay differential (TGD1,TGD2) Age of data, clock (AODC) Clock correction parameters (t oc, a0, a1, a2) Age of data, ephemeris (AODE) Ephemeris parameters (toe,A, , i0, IDOT, Cuc，e, ω, Δn, M0, Ω0, Cus, Crc, Crs, Cic, Cis)Page number (Pnum)Almanac information: Almanac parameters (toa,A, , δi, a0, a1)e, ω, M0, Ω0, Almanac week number (WNa) Satellite health information (Heai, i=1~30)Time offsets from other systems: Time parameters relative to UTC (A0UTC, A1UTC, ΔtLS, WNLSF, DN,67BDS-SIS-ICD-2.02013-12 2013 China Satellite Navigation OfficeΔtLSF) Time parameters relative to GPS time (A0GPS, A1GPS) Time parameters relative to Galileo time (A0Gal, A1Gal) Time parameters relative to GLONASS time (A0GLO, A1GLO)The definition of basic NAV information is the same as that in format D1,except the page number (Pnum), seconds of week (SOW), which are differentfrom those in format D1.
Thus only the meanings of Pnum and SOW are givenas follows.(1)Page number (Pnum)In format D2, the information of subframe 5 is broadcast via 120 pages andthe page number is identified by Pnum.(2)Seconds of week (SOW)In format D2, the bits 19 through 26 and the bits 31 through 42, altogether20 bits of every subframe are for the seconds of week (SOW). SOW count startsfrom zero at 00:00:00 of BDT on every Sunday.In format D2, SOW refers to the leading edge of preamble first bit insubframe 1 of each frame.5.3.3.2 Page Number for Basic NAV Information (Pnum1)The bits 43 through 46, altogether 4 bits of subframe 1 are for page numberof the basic NAV information (Pnum1).
Pnum1 is broadcast in pages 1 through10 of subframe 1.5.3.3.3 PageNumber for IntegrityInformation (Pnum2)andDifferentialCorrectionThe bits 44 through 47, altogether 4 bits of the subframe 2 are for the pagenumber of the integrity and differential correction information (Pnum2). Pnum2are broadcast in pages 1 through 6 of subframe 2.68BDS-SIS-ICD-2.02013-12 2013 China Satellite Navigation Office5.3.3.4 Satellite Health Flag for Integrity and Differential CorrectionInformation (SatH2)The satellite health flag for integrity and differential correction informationSatH2 is in 2 bits. The MSB indicates the check result of the satellite for thereceived up-link regional user range accuracy (RURA), user differential rangeerror (UDRE) and equivalent clock correction (Δt).
The LSB indicates the checkresult of the satellite for received up-link ionospheric grid information.See Table 5-20 for detailed definitions.Table 5-20Bit allocationMSBLBSSatH2 definitionsCodeDefinition of SatH20RURA, UDRE and Δt are good by check1RURA, UDRE and Δt are bad by check0Ionospheric grid information is good by check1Ionospheric grid information is bad by check5.3.3.5 BDS Satellite Identification for Integrity and differentialcorrection information (BDIDi)The BDS satellite identification for integrity and differential correctioninformation (BDIDi, i=1~30) is in 30 bits to identify BDS satellites for whichthe integrity and differential information are broadcast. Every bit identifies onesatellite.
―1‖ means the integrity and differential correction information for thesatellite are broadcast and ―0‖ means not.For BDS the integrity and differential correction information of 18satellites at most can be broadcast once continuously. Integrity and differentialcorrection information are allocated in ascending order of the SV ID.5.3.3.6 BDS Regional User Range Accuracy Index (RURAI)Regional User Range Accuracy (RURA), the BDS satellite signal integrityinformation, is used to describe the satellite signal pseudo-range error in meters.The satellite signal integrity information is indicated with the Regional User69BDS-SIS-ICD-2.02013-12 2013 China Satellite Navigation OfficeRange Accuracy Index (RURAI).
It occupies 4 bits for each satellite so theeffective range of RURAI is 0 to 15. The update rate is 18 seconds. See Table5-21 for the corresponding relationship between RURAI and RURA.Table 5-21RURAI definitionsRURAIRURA（meters, 99.9%）00.7511.021.2531.7542.2553.063.7574.585.2596.0107.51115.01250.013150.014300.015> 300.05.3.3.7 BDS Differential Correction and Differential Correction IntegrityInformation (Δt, UDREI)5.3.3.7.1 Equivalent Clock Correction (Δt)The BDS differential correction information is expressed in equivalentclock correction (Δt).
It occupies 13 bits for each satellite with the unit and scalefactor of meter and 0.1 respectively and is expressed with two’s complement.The MSB is for the sign bit (+ or –). The update rate of Δt is every 18 seconds.The user adds the value of Δt to the observed pseudorange to correct theresidual error of the satellite clock offset and ephemeris.70BDS-SIS-ICD-2.02013-12 2013 China Satellite Navigation OfficeThe equivalent clock correction Δt broadcasted on B1I and B2I isrespectively related to its own carrier frequency.
It is not necessary that Δtbroadcasted on B1I and B2I is the same. It means the Δt is not available if thevalue is -4096.5.3.3.7.2 User Differential Range Error Index (UDREI)User differential range error (UDRE), the BDS differential correctionintegrity, is used to describe the error of equivalent clock correction in meters. Itis indicated by user differential range error index (UDREI). It occupies 4 bitsfor each satellite within the range of 1~15 and the update rate is 3 seconds.
Thecorresponding relationship between UDRE and UDREI is shown in Table 5-22.The user shall lookup UDRE in the table to determine the accuracy of thedifferential correction for the satellite.Table 5-22 UDREI definitionsUDREIUDRE（meters, 99.9％）01.011.522.033.044.055.066.078.0810.0915.01020.01150.012100.071BDS-SIS-ICD-2.02013-12 2013 China Satellite Navigation OfficeUDREIUDRE（meters, 99.9％）13150.014Not monitored15Not available5.3.3.8 Ionospheric Grid Information (Ion)The information about each ionospheric grid point (Ion) consists of thevertical delay at grid point (dτ) and its error index (GIVEI), occupying 13 bitsaltogether.
The data arrangement and definitions are as follows.Table 5-23Ion definitionsParameterdτGIVEINo. of bits94The ionospheric grid covers 70 to 145 degrees east longitude and 7.5 to 55degrees north latitude. This area is divided into 320 grids of 5×2.5 degrees. Thedefinition of ionospheric grid point (IGP) numbers less than or equal to 160 islisted in Table 5-24-1. Pages 1 through 13 broadcast ionospheric grid correctioninformation according to this table.Table 5-24-1E-Log.N-Lat.55504540353025201510IGP numbers70 7580859095 100 105 110 115 120 125 130 135 140 14510987654321302928272625242322214039383736353433323150494847464544434241605958575655545352512019181716151413121170696867666564636261807978777675747372717290 100 110 120 130 140 150 16089 99 109 119 129 139 149 15988 98 108 118 128 138 148 15887 97 107 117 127 137 147 15786 96 106 116 126 136 146 15685 95 105 115 125 135 145 15584 94 104 114 124 134 144 15483 93 103 113 123 133 143 15382 92 102 112 122 132 142 15281 91 101 111 121 131 141 151BDS-SIS-ICD-2.02013-12 2013 China Satellite Navigation OfficeWhen IGP≤160, the corresponding longitudes and latitudes are:L 70 INT((IGP 1) / 10) 5B 5 (IGP INT((IGP 1) / 10) 10) 5Where INT(*) refers to round down.The definition of ionospheric grid point (IGP) numbers more than 160 isshown in Table 5-24-2.
Pages 60 through 73 broadcast grid ionosphericcorrection information according to this table.Table 5-24-2E-Log.N-Lat.52.547.542.537.532.527.522.517.512.57.5IGP numbers70 7580859095 100 105 110 115 120 125 130 135 140 145170169168167166165164163162161190189188187186185184183182181200199198197196195194193192191210209208207206205204203202201220219218217216215214213212211180179178177176175174173172171230229228227226225224223222221240239238237236235234233232231250249248247246245244243242241260259258257256255254253252251270269268267266265264263262261280279278277276275274273272271290289288287286285284283282281300299298297296295294293292291310309308307306305304303302301320319318317316315314313312311When IGP > 160, the corresponding longitudes and latitudes are:L 70 INT((IGP 161) / 10) 5B 2.5 (IGP 160 INT((IGP 161) / 10) 10) 5Where INT(*) refers to round down.5.3.3.8.1 Vertical Delay at Ionospheric Grid Points (dτ)dτi is the vertical ionosphere delay on B1I signal at the ith grid point,expressed in scale factor of 0.125 and with unit of meters.
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