IS-GPS-200H (797934), страница 30
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The timing of thesubframes and pages is covered in Section 40.3.4.40.3.3.1 Telemetry Word.The TLM word shall be as specified in Appendix II, Section 20.3.3.1.40.3.3.2 Handover Word (HOW).The HOW shall be as specified in Appendix II, Section 20.3.3.2.40.3.3.3 Subframe 1.Subframe 1 shall be as specified in Appendix II, Section 20.3.3.3.40.3.3.4 Subframes 2 and 3.Subframes 2 and 3 shall be as specified in Appendix II, Section 20.3.3.4.40.3.3.5 Subframes 4 and 5.Both subframe 4 and 5 are subcommutated 25 times each; the 25 versions of these subframes arereferred to as pages 1 through 25 of each subframe.
With the possible exception of "reserved forsystem use" pages and explicit repeats, each page contains different specific data in words threethrough ten. As shown in Figure 40-1, the pages of subframe 4 utilize seven different formats,while those of subframe 5 use two. The content of words three through ten of each page isdescribed below, followed by algorithms and material pertinent to the use of the data.40.3.3.5.1 Content of Subframes 4 and 5.Words three through ten of each page contain six parity bits as their LSBs; in addition, two noninformation bearing bits are provided as bits 23 and 24 of word ten in each page for paritycomputation purposes.
The data contained in the remaining bits of words three through ten ofthe various pages in subframes 4 and 5 are described in the following subparagraphs.A brief summary of the various data contained in each page of subframes 4 and 5 is as follows:207IS-GPS-200H24 Sep 2013SubframePage(s)Data41, 6, 11, 16 and 21Reserved2, 3, 4, 5, 7, 8, and 9Almanac data for SV ID 89 through 95 (PRN 57 through 63)respectively10Reserved12, 19, 20, 22, 23 and 24Reserved13NMCT14 and 15Reserved for system use17Special messages18Ionospheric and UTC data25A-S flags/SV configurations for 31 SVs, plus SV health for SV ID 89through 95 (PRN 57 through 63)51 through 24Almanac data for SV ID 65 through 88 (PRN 33 through 56)25SV health data for SV ID 65 through 88 (PRN 33 through 56), thealmanac reference time, the almanac reference week number40.3.3.5.1.1 Data ID and SV ID.The two MSBs of word three in each page shall contain the data ID.
Data ID number two(denoted by binary code 01) denotes the LNAV data structure of D(t) which is described in thisAppendix. Future data IDs will be defined as necessary.As shown in Table 40-V, the data ID is utilized to provide one of two indications: (a) for thosepages which are assigned to contain the almanac data of one specific SV, the data ID defines thedata structure utilized by that SV whose almanac data are contained in that page; and (b) for allother pages, the data ID denotes the data structure of the transmitting SV.The six LSBs of the SV ID are given by bits three through eight of word three in each page asshown in Table 40-V. Specific IDs are reserved for each page of subframes 4 and 5. The SVIDs are utilized in two different ways: (a) for those pages which contain the almanac data of agiven SV, the SV ID is equal to 32 plus the number that is assigned to the PRN code phase ofthat SV (reference Tables 3-Ia and 3-Ib), and (b) for all other pages the SV ID assigned inaccordance with Table 40-V serves as the "page ID".
IDs 65 through 95 are assigned to thosepages which contain the almanac data of specific SVs (pages 1-24 of subframe 5 and pages 2-5and 7-9 of subframe 4). The "0" ID (binary all zeros) is assigned to indicate a dummy SV, whileIDs 115 through 127 are utilized for pages containing other than almanac data of a specific SV.208IS-GPS-200H24 Sep 2013IDs 116 through 126 have the same data as LNAV-L IDs 52 through 62. ID 115 is the LNAV-Uanalog of ID 51 in LNAV-L, while ID 127 is the LNAV-U analog of ID 63 in LNAV-L.Pages which carry the same SV ID (e.g., in subframe 4, pages 1, 6, 11, 16 and 21 carry an ID of121, while pages 12 and 24 are designated by an ID of 126) may not be considered to containidentical data. The data in the pages with the same SV ID can be different. Pages 1, 6, 11, 16and 21 reference Appendix II. Pages 12, 19, 20, 22, 23 and 24 reference Appendix II.
Pages 14and 15: (Reference Appendix II)Table 40-V. Data IDs and SV IDs in Subframes 4 and 5Subframe 4PageData IDSubframe 5SV ID*Data ID(Note 4)12345678910111213141516171819202122232425Note(2)Note(1)Note(1)Note(1)Note(1)Note(2)Note(1)Note(1)Note(1)Note(2)Note(2)Note(2)Note(2)Note(2)Note(2)Note(2)Note(2)Note(2)Note(2)Note(2)Note(2)Note(2)Note(2)Note(2)Note(2)121899091921219394950121126116117118121119120122 Note(3)123 Note(3)121124 Note(3)125 Note(3)126127SV ID*(Note 4)Note(1)Note(1)Note(1)Note(1)Note(1)Note(1)Note(1)Note(1)Note(1)Note(1)Note(1)Note(1)Note(1)Note(1)Note(1)Note(1)Note(1)Note(1)Note(1)Note(1)Note(1)Note(1)Note(1)Note(1)Note(2)656667686970717273747576777879808182838485868788115* Use "0" to indicate "dummy" SV. When using "0" to indicate dummy SV, use the dataID of the transmitting SV.Note 1:Data ID of that SV whose SV ID appears in that page.Note 2:Data ID of transmitting SV.Note 3:SV ID may vary (except for IIR/IIR-M/IIF / and GPS III SVs).Note 4:For almanac data pages, the SV ID relationship to PRN ID is defined inTable 3-Ia and Table 3-Ib209IS-GPS-200H24 Sep 201340.3.3.5.1.2 Almanac Data.Pages 1 through 24 of subframe 5, as well as pages 2 through 5 and 7 through 9 of subframe 4contain the almanac data and a SV health word for up to 31 SVs (the health word is discussed inparagraph 40.3.3.5.1.3).
The almanac data are a reduced-precision subset of the clock andephemeris parameters. The data occupy all bits of words three through ten of each page exceptthe eight MSBs of word three (data ID and SV ID), bits 17 through 24 of word five (SV health),and the 50 bits devoted to parity. The number of bits, the scale factor (LSB), the range, and theunits of the almanac parameters are given in Table 20-VI. The algorithms and other materialrelated to the use of the almanac data are given in paragraph 40.3.3.5.2.The almanac message for any dummy SVs shall contain alternating ones and zeros with validparity.The almanac parameters shall be updated by the CS at least once every 6 days while the CS isable to upload the SVs. If the CS is unable to upload the SVs, the accuracy of the almanacparameters transmitted by the SVs will degrade over time.For Block IIA SVs, three sets of almanac shall be used to span at least 60 days.
The first andsecond sets will be transmitted for up to six days each; the third set is intended to be transmittedfor the remainder of the 60 days minimum, but the actual duration of transmission will dependon the individual SV's capability to retain data in memory. All three sets are based on six-daycurve fits that correspond to the first six days of the transmission interval.
For Block IIR/IIR-M,IIF and GPS III SVs, multiple sets of almanac parameters shall be uploaded to span at least 60days.40.3.3.5.1.3 SV Health.Subframes 4 and 5 contain two types of SV health data: (a) each of the 31 pages which containthe clock/ephemeris related almanac data provide an eight-bit SV health status word regardingthe SV whose almanac data they carry, and (b) the 25th page of subframe 4 and of subframe 5jointly contain six-bit health status data for up to 31 SVs.The three MSBs of the eight-bit health words indicate health of the LNAV data in accordancewith the code given in Table 20-VII. The six-bit words provide a one-bit summary of the LNAVdata's health status in the MSB position in accordance with paragraph 40.3.3.3.1.4. The fiveLSBs of both the eight-bit and the six-bit words provide the health status of the SV's signalcomponents in accordance with the code given in Table 20-VIII.
A special meaning is assigned,however, to the "6 ones" combination of the six-bit health words in the 25th page of subframes 4and 5: it indicates that "the SV which has that ID is not available and there may be no dataregarding that SV in that page of subframes 4 and 5 that is assigned to normally contain thealmanac data of that SV" (NOTE: this special meaning applies to the 25th page of subframes 4210IS-GPS-200H24 Sep 2013and 5 only). The health indication shall be given relative to the "as designed" capabilities ofeach SV (as designated by the configuration code -- see paragraph 40.3.3.5.1.4).
Accordingly,any SV which does not have a certain capability will be indicated as "healthy" if the lack of thiscapability is inherent in its design or it has been configured into a mode which is normal from auser standpoint and does not require that capability.Additional SV health data are given in subframe 1. The data given in subframes 1, 4, and 5 ofthe other SVs may differ from that shown in subframes 4 and/or 5 since the latter may beupdated at a different time.The eight-bit health status words shall occupy bits 17 through 24 of word five in those 31 pageswhich contain almanac data for individual SVs.
The six-bit health status words shall occupy the24 MSBs of words four through nine in page 25 of subframe 5 plus bits 19 through 24 of word 8,the 24 MSBs of word 9, and the 12 MSBs of word 10 in page 25 of subframe 4.The predicted health data will be updated at the time of upload when a new almanac has beenbuilt by the CS. The transmitted health data may not correspond to the actual health of thetransmitting SV or other SVs in the constellation.40.3.3.5.1.4 Anti-Spoof (A-S) Flags and SV Configurations.Page 25 of subframe 4 shall contain a four-bit-long term for each of up to 31 SVs to indicate theA-S status and the configuration code of each SV transmitting with a PRN number in the rangeof 33 through 63.
The MSB of each four-bit term shall be the A-S flag with a "1" indicating thatA-S is ON. The three LSBs shall indicate the configuration of each SV using the followingcode:Code SV Configuration000Reserved001A-S capability, plus flags for A-S and "alert" in HOW; memory capacity as described inparagraph 20.3.2 (e.g. Block II/IIA/IIR SV).010A-S capability, plus flags for A-S and "alert" in HOW; memory capacity as described inparagraph 20.3.2, M-Code signal capability, L2C signal capability (e.g., Block IIR-M SV).011A-S capability, plus flags for A-S and "alert" in HOW; memory capacity as described inparagraph 20.3.2, M-Code capability, L2C signal capability, L5 signal capability (e.g., Block IIFSV).100A-S capability, plus flags for A-S and "alert" in HOW; memory capacity as described inparagraph 20.3.2, M-Code capability, L1C signal capability, L2C signal capability, L5 signalcapability, no SA capability (e.g., GPS III SV).211IS-GPS-200H24 Sep 2013Additional codes will be assigned in the future, should the need arise.These four-bit terms shall occupy bits 9 through 24 of word three, the 24 MSBs of words fourthrough seven, and the 12 MSBs of word eight, all in page 25 of subframe 4.Since the anti-spoof information is updated by the CS at the time of upload, the anti-spoof datamay not correspond to the actual anti-spoof status of the transmitting SV or other SVs in theconstellation.40.3.3.5.1.5 Almanac Reference Week.The almanac reference week shall be as specified in Appendix II, paragraph 20.3.3.5.1.5.40.3.3.5.1.6 Coordinated Universal Time (UTC) Parameters.The UTC parameters shall be as specified in Appendix II, paragraph 20.3.3.5.1.6.40.3.3.5.1.7 Ionospheric Data.The ionospheric data shall be as specified in Appendix II, paragraph 20.3.3.5.1.7.40.3.3.5.1.8 Special Messages.The special messages shall be as specified in Appendix II, paragraph 20.3.3.5.1.8.40.3.3.5.1.9 NMCT.Page 13 of subframe 4 shall contain the NMCT data appropriate to the transmitting SV.
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