Galileo OS SIS ICD (797928), страница 13
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In normal operation the navigation data (ephemeris, clock correction) have limited©, 2006, European Space Agency / Galileo Joint UndertakingDocument subject to terms of use and disclaimers p. 2-4.Reference:Issue:Revision:Date:GAL OS SIS ICD/D.0Draft023/05/2006Page75validity duration depending on the data type. Also several batches of data are stored on boardthe satellite. Each batch is identified by an issue number.This enables: to ensure consistency at user level between the different batches of data received fromdifferent satellites. to indicate to the user receiver the validity of the data (which have to be updated usingnew issue of navigation data).For that purpose, the IOD is transmitted in each page that includes navigation data in order toenable the user receiver to compute the full batch of data even if it misses some pages or startsto receive the data somewhere during the transmission.Moreover, this IOD is correlated to the reference time of the data set t0e, indicating thecomputation of the data.
This t0e origin starts with the WN update and covers a complete week(to be consistent with the IOD) with a 1 minute accuracy. This requires that the parameter t0eis coded on 14 bits.BBBBBBThe IOD is transmitted in each page of the message, with the size dependent on the data typeas given in Table 62.48HData typeEphemeris and Clock correction IODnavAlmanacs IODaNumber of bits102Table 63: IOD values mapping on data typeThe ephemeris validity duration of 240 minutes is taken into account from the reference timeof the data.10.1.3.3 Navigation Data Validity and Signal Health Status in F/NAVThe signal health status refers to the transmitting satellite, being the size and meaning ofvalues specific for each signal.The validity and the update rate of the health status depends on the applications needs.
Thishealth status could be used as a service performance level notification (e.g. notification ofsatellite non availability) for some applications requiring high level of safety. The healthstatus update rate is optimised to meet such requirements.The navigation data validity status transmitted on E5a, E5b and E1, is coded on 1 bit,according to Table 63 and Table 64.485H486HParameterDefinitionBitsScale factorUnitE5aDVSE5a Data validity status1NAdimensionlessBBTable 64: Data validity satellite status (transmitted on E5a)©, 2006, European Space Agency / Galileo Joint UndertakingDocument subject to terms of use and disclaimers p.
2-4.Reference:Issue:Revision:Date:GAL OS SIS ICD/D.0Draft023/05/2006Page76ParameterDefinitionBitsScale factorUnitE5bDVSE5b Data validity status1NAdimensionlessE1-B Data validity status1NAdimensionlessBBE1-BDVSBBBBTable 65: Data validity satellite status (transmitted on E5b and E1-B)The data validity status bit has the values shown in Table 65:487HData validity status01DefinitionNavigation Data validWorking without guaranteeTable 66: Data validity status bit valuesThe E5a Signal health status transmitted on E5a-I is coded on 2 bits according to Table 66.48HParameterDefinitionBitsScale factorUnitE5aHSE5a Signal health status2NADimensionlessBBTable 67: Signal health status for E5a (transmitted on E5a)The signal status bits have the values shown in Table 67.489HSignal Health statusDefinition0Signal OK1Signal out of service2Signal will be out of service3Signal Component currently in TestTable 68: Signal health status bit values10.1.3.4 ChecksumThe checksum, which employs a CRC technique, is used to detect the reception of corrupteddata.
The checksum does not include the frame synchronisation pattern or the tail bit fieldssince these do not form part of the required message information.For the F/NAV a CRC of 24 bits is generated from the generator polynomial of Eq. 21:490HG(X) = (1+X)*P(X)Eq. 21where P(X) is a primitive and irreducible polynomial given by the following Eq. 22:491H©, 2006, European Space Agency / Galileo Joint UndertakingDocument subject to terms of use and disclaimers p.
2-4.Reference:Issue:Revision:Date:GAL OS SIS ICD/D.0Draft023/05/2006Page77P(X) = (X23 + X17 + X13 + X12 + X11 + X9 + X8 + X7 + X5 + X3 + 1)PPPPPPPPPPPPPPPPPPPEq. 22PThe CRC is composed of a sequence of 24 parity bits pi; for any i from 1 to 24, pi is thecoefficient of X24-i in R(X) where: R(X) is the remainder of the binary polynomial algebra division of G(X) by thepolynomial m(X) X24 and2k-1 m(X) = mk + mk-1 X + mk-2 X + ...+ m1X with m1, m2, ..., mk the sequence ofinformation bits to be protected by the CRC.BBBBPPPPBBBBBBPPBBPPBBBBBB10.1.4 AlmanacThe almanac data is a reduced-precision subset of the clock and ephemeris parameters of theactive satellites in orbit.The almanac is broadcast by every satellite so to enable the user to improve the acquisitiontime of the satellite to reduce the search window.
Indeed, knowing an approximate position ofthe satellite, the user can estimate the Doppler effect due to this position and then speed up thesynchronisation between the codes of the satellite and the one generated locally.The proposed Galileo almanac orbital parameters consist of: Mean of semi-major axis Eccentricity Inclination Right ascension of the ascending node Argument of perigee Mean anomalyA reduced set of clock correction parameters is provided in the almanac for each satelliteincluding the Time of applicability ToA of the almanac data. This almanac reference time t0ais referenced to the almanac reference week (WNa).The WNa term consists of eight bits, which is a Modulo 256 binary representation of the GSTweek number.Additionally, a predicted satellite health status is to be provided for each of these satellites,giving indications on the satellite's signal components health and navigation data health.
Inparticular, this Health status informs the user when one satellite is temporarily out or will betemporarily out during a predicable period. One bit is used to summarise the predicted healthof the navigation data. The number of possible signal health status values depends on theservice and on the frequencies allocated to each service.B©, 2006, European Space Agency / Galileo Joint UndertakingDocument subject to terms of use and disclaimers p.
2-4.BReference:Issue:Revision:Date:GAL OS SIS ICD/D.0Draft023/05/2006Page78Finally, the IODa allows identifying without ambiguity an almanac batch. The update ratebeing slow, two bits are enough.The almanac parameters are transmitted according to the characteristics stated in Table 68.492HNumber ofbitsScalefactor61Square root of the absolute value of thedeviation of the mean semi-major axis from itsnominal value17*2-9Eccentricity112-16ParameterDefinitionSVIDsatellite ID (1 constellation of 36 satellites)(∆a)1/2PPeδiBInclination at reference time relative to i0 = 56°BΩBB11*PUnitdimensionlessmeters1/2PPPP-142PP-15Pdimensionlesssemi-circlesRight ascension16*2ΩRate of right ascension11*2-33semi-circles/secωArgument of perigee16*2-15semi-circles16*-15semi-circles0PPsemi-circles•M0BSatellite mean anomaly at reference timeBaf0BSatellite clock correction bias “truncated”Baf1BSatellite clock correction linear “truncated”BSVstatus**BPBSatellite signal health statusPTotal almanac satellite parameters2 (F/NAV)4 (I/NAV)2PP-192PP-382PPSecondsSeconds/secNAdimensionless131(F/NAV)133 (I/NAV)Almanac Issue Of Data2NAdimensionlesst0aAlmanac reference time84096SecondsAlmanac reference Week Number8181BWNa**11*PPIODaB*14*PPWeekTotal almanac reference parametersParameters so indicated are two’s complement, with the sign bit (+or-) occupying the MSBThe F/NAV almanac transmitted through the E5a contains the signal health status SVstatus(E5aHS) codedon 2 bits.The I/NAV almanac transmitted through the E5b and E1 contains both signal health statusSVstatus(E5bHS) and SVstatus(E1HS) coded on 2 bits each.BBBBBBBBBTable 69: Almanac parameters©, 2006, European Space Agency / Galileo Joint UndertakingDocument subject to terms of use and disclaimers p.
2-4.BBBReference:Issue:Revision:Date:GAL OS SIS ICD/D.0Draft023/05/2006Page7911. ANNEX 1 – RANDOMLY GENERATED CODESTPThis annex provides the optional memory based primary codes (expressed in hexadecimalformat) for the Galileo Open Signal components E5a-I, E5a-Q, E5b-I, E5b-Q, E1-B, E1-C.The corresponding secondary codes are described in section 6.3.11.1 HEXADECIMAL CODING CONVENTIONGenerally, one hexadecimal symbol (0,..,9, A,..,F) corresponds to four succeeding code-chips.The leftmost code-chip corresponds to the first code-chip in time, and the rightmost code-chipcorresponds to the last code-chip in time.
The first group is built with the first four code-chips, thesecond group with the fifth to eighth code-chip etc.For primary codes whose length is not dividable by four, the last hexadecimal symbol is built from thelast group of code-chips, filled up with zeros at the end in time (to the right) to reach a final length of 4binary symbols.The translation from the chip-stream to hexadecimal symbol stream is illustrated with an examplecode of length 10 in Figure 16.493HTime [in Chip]123456789101112Logic representationof chip-values1110110011--logic representation filledup with zeros at the end111011000100×2×4Logic to decimaltranslation×1×8PP×1×8PPPPPP×2×4×2×4PP×1×8PPDecimal representation14124HexadecimalRepresentationEC4Figure 16: Example for the translation of logical (binary) spreading code intohexadecimal representationTable 69 summarizes these code properties.49H©, 2006, European Space Agency / Galileo Joint UndertakingDocument subject to terms of use and disclaimers p.
2-4.ChannelReference:Issue:Revision:Date:GAL OS SIS ICD/D.0Draft023/05/2006Page80Primary Code length(chips)Number ofNumber of filledNumber ofhexadecimalup zerosdefined codessymbolsE5a-I102302558250E5a-Q102302558250E5b-I102302558250E5b-Q102302558250E1-B40921023050E1-C40921023050Table 70: Primary code-length and hexadecimal representation characteristics for thedifferent Galileo signal components.©, 2006, European Space Agency / Galileo Joint UndertakingDocument subject to terms of use and disclaimers p. 2-4.Reference:Issue:Revision:Date:GAL OS SIS ICD/D.0Draft023/05/2006Page8111.2 PRIMARY CODES FOR THE E5A-I SIGNAL COMPONENT-------------------------------------------------------------------------------------------------------------------------------------------------------------------------E5aI Code No 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-------------------------------------------------------------------------------------------------------------------------------------------------------------------------E5aI Code No 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--------------------------------------------------------------------------------------------------------------------------------------------------------------------------©, 2006, European Space Agency / Galileo Joint UndertakingDocument subject to terms of use and disclaimers p.
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