Интерфейсный документ GPS, страница 11

Data Format (sheet 5 of 11)IS-GPS-200D7 Dec 200473DIRECTION OF DATA FLOW FROM SV150 BITSWORD 1SUBFRAMENO.PAGENO.WORD 2WORD 3WORD 4WORD 561131TLM4MSB FIRST3 SECONDS1, 6, 11,16 & 2163 6991121HOWC Pt22 BITSP16BITS***22 BITSP24 BITS***PP24 BITS***DATA ID - 2 BITSSV (PAGE) ID - 6 BITSDIRECTION OF DATA FLOW FROM SV150 BITSWORD 6WORD 715141, 6, 11,16 & 21WORD 818124 BITS***PWORD 921124 BITS***MSB FIRST3 SECONDSP24124 BITS***P8***BITSWORD 1024916BITS***271P22 BITS**tP** RESERVED FOR SYSTEM USE*** RESERVEDP = 6 PARITY BITSt = 2 NONINFORMATION BEARING BITS USED FOR PARITY COMPUTATION (SEE PARAGRAPH 20.3.5)C = TLM BITS 23 AND 24 WHICH ARE RESERVEDFigure 20-1. Data Format (sheet 6 of 11)IS-GPS-200D7 Dec 200474DIRECTION OF DATA FLOW FROM SV150 BITSWORD 1SUBFRAMENO.PAGENO.WORD 2WORD 3WORD 4WORD 561131TLM4MSB FIRST3 SECONDS12, 19, 20,22, 23 & 2463 6991121HOWC Pt22 BITSP16BITS***22 BITSP24 BITS***PP24 BITS***DATA ID - 2 BITSSV (PAGE) ID - 6 BITSDIRECTION OF DATA FLOW FROM SV150 BITSWORD 6WORD 7151412, 19, 20,22, 23 & 24WORD 818124 BITS***PWORD 921124 BITS***MSB FIRST3 SECONDSP24124 BITS***P8***BITSWORD 1024916 BITS**271P22 BITS**tP** RESERVED FOR SYSTEM USE*** RESERVEDP = 6 PARITY BITSt = 2 NONINFORMATION BEARING BITS USED FOR PARITY COMPUTATION (SEE PARAGRAPH 20.3.5)C = TLM BITS 23 AND 24 WHICH ARE RESERVEDFigure 20-1.

Data Format (sheet 7 of 11)IS-GPS-200D7 Dec 200475DIRECTION OF DATA FLOW FROM SV150 BITSWORD 1SUBFRAMENO.PAGENO.WORD 2WORD 3WORD 4WORD 561131TLM4MSB FIRST3 SECONDS63 69t22 BITS9199107121129137α0α2β1α1α3β0β2β388P888P888PBITS BITSBITS BITS BITSBITS BITS BITSHOWC P1877P22 BITSDATA ID - 2 BITSSV (PAGE) ID - 6 BITSDIRECTION OF DATA FLOW FROM SV150 BITSWORD 6WORD 715118WORD 8181A14211219227WORD 9241249257WORD 1027124 BITStot∆tLS∆tLSFWNtDN8PP888888BITS BITS BITSBITS BITS BITSBITSMSBsLSBsP24 BITSMSB FIRST3 SECONDSP27914BITS**tPWNLSFA0 - 32 BITS TOTAL** RESERVED FOR SYSTEM USEP = 6 PARITY BITSt = 2 NONINFORMATION BEARING BITS USED FOR PARITY COMPUTATION (SEE PARAGRAPH 20.3.5)C = TLM BITS 23 AND 24 WHICH ARE RESERVEDFigure 20-1.

Data Format (sheet 8 of 11)IS-GPS-200D7 Dec 200476DIRECTION OF DATA FLOW FROM SV150 BITSWORD 1SUBFRAMENO.PAGENO.WORD 2WORD 3WORD 4WORD 56113163 69TLM4MSB FIRST3 SECONDSHOWC P25t22 BITS91A-SPOOF &SV CONFIGPSV SV SV SV1 2 3 422 BITSP121A- SPOOF &SV CONFIGSV SV SV SV SV SV5 6 7 8 9 10PA- SPOOF &SV CONFIGSV SV SV SV SV SV11 12 13 14 15 16PDATA ID - 2 BITSSV (PAGE) ID - 6 BITSDIRECTION OF DATA FLOW FROM SV150 BITSWORD 6MSB FIRST3 SECONDSWORD 7WORD 8WORD 9WORD 10227151A- SPOOF &SV CONFIG425SV SV SV SV SV SV17 18 19 20 21 22181P211A- SPOOF &SV CONFIGSV SV SV SV SV SV23 24 25 26 27 28P229241271SV25SV HEALTH6 BITS/SVPSV SV SV SV26 27 28 29SV HEALTH6 BITS/SVSV SV SV30 31 32A-SPOOF &SV CONFIGSV SV SV SV29 30 31 32P2 BITS **t PSV HEALTH - 6 BITS** RESERVED FOR SYSTEM USEP = 6 PARITY BITSt = 2 NONINFORMATION BEARING BITS USED FOR PARITY COMPUTATION (SEE PARAGRAPH 20.3.5)C = TLM BITS 23 AND 24 WHICH ARE RESERVED4 BITS **Figure 20-1.

Data Format (sheet 9 of 11)IS-GPS-200D7 Dec 200477DIRECTION OF DATA FLOW FROM SV150 BITSWORD 1SUBFRAMENO.PAGENO.WORD 231TLM4WORD 361171HOWt22 BITSWORD 4WORD 56963C P13MSB FIRST3 SECONDSP22 BITS91ERD1ERD2ERD36BITS6BITS2MSBSP121ERD3ERD4ERD5ERD6ERD74LSBS6BITS6BITS6BITS2MSBSPERD7ERD8ERD94LSBS6BITS6BITSERD10ERD116BITS2MSBSPDATA ID - 2 BITSAVAILABILITY INDICATOR - 2 BITSSV (PAGE) ID - 6 BITSDIRECTION OF DATA FLOW FROM SV150 BITSWORD 6WORD 7151413WORD 8181ERD11ERD12ERD13ERD14ERD154LSBS6BITS6BITS6BITS2MSBSPMSB FIRST3 SECONDSWORD 9211ERD15ERD16ERD17ERD18ERD194LSBS6BITS6BITS6BITS2MSBSPWORD 10241ERD19ERD20ERD21ERD22ERD234LSBS6BITS6BITS6BITS2MSBSP271ERD23ERD24ERD25ERD26ERD274LSBS6BITS6BITS6BITS2MSBSPERD27ERD28ERD29ERD304LSBS6BITS6BITS6BITStPP = 6 PARITY BITSt = 2 NONINFORMATION BEARING BITS USED FOR PARITY COMPUTATION (SEE PARAGRAPH 20.3.5)C = TLM BITS 23 AND 24 WHICH ARE RESERVEDFigure 20-1.

Data Format (sheet 10 of 11)IS-GPS-200D7 Dec 200478DIRECTION OF DATA FLOW FROM SV150 BITSWORD 1SUBFRAMENO.PAGENO.WORD 2WORD 3WORD 4WORD 561131TLM14, 15& 17**4MSB FIRST3 SECONDS63 6991121HOWC Pt22 BITSP16BITS**22 BITSP24 BITS**PP24 BITS**DATA ID - 2 BITSSV (PAGE) ID - 6 BITSDIRECTION OF DATA FLOW FROM SV150 BITSWORD 6WORD 715114, 15& 17**4WORD 818124 BITS**PWORD 921124 BITS**MSB FIRST3 SECONDSPWORD 1024124 BITS**P27124 BITS**P22 BITS**tP**THE INDICATED PORTIONS OF WORDS 3 THROUGH 10 OF PAGES 14 AND 15 ARE RESERVED FOR SYSTEM USE, WHILETHOSE OF PAGE 17 ARE RESERVED FOR SPECIAL MESSAGES PER PARAGRAPH 20.3.3.5.1.10P = 6 PARITY BITSt = 2 NONINFORMATION BEARING BITS USED FOR PARITY COMPUTATION (SEE PARAGRAPH 20.3.5)C = TLM BITS 23 AND 24 WHICH ARE RESERVEDFigure 20-1.

Data Format (sheet 11 of 11)IS-GPS-200D7 Dec 200479(This page intentionally left blank.)IS-GPS-200D7 Dec 20048020.3.3 Message Content. The format and contents of the TLM word and the HOW, as well as those of words threethrough ten of each subframe/page, are described in the following subparagraphs. The timing of the subframes andpages is covered in Section 20.3.4.20.3.3.1 Telemetry Word. Each TLM word is 30 bits long, occurs every six seconds in the data frame, and is thefirst word in each subframe/page. The format shall be as shown in Figure 20-2. Bit 1 is transmitted first. EachTLM word shall begin with a preamble, followed by the TLM message, two reserved bits, and six parity bits.

TheTLM message contains information needed by the authorized user and by the CS, as described in the related SS/CSinterface documentation.20.3.3.2Handover Word (HOW).The HOW shall be 30 bits long and shall be the second word in eachsubframe/page, immediately following the TLM word. A HOW occurs every 6 seconds in the data frame. Theformat and content of the HOW shall be as shown in Figure 20-2. The MSB is transmitted first. The HOW beginswith the 17 MSBs of the time-of-week (TOW) count. (The full TOW count consists of the 19 LSBs of the 29-bit Zcount). These 17 bits correspond to the TOW-count at the X1 epoch which occurs at the start (leading edge) of thenext following subframe (reference paragraph 3.3.4).Bit 18 is an "alert" flag.

When this flag is raised (bit 18 = "1"), it shall indicate to the unauthorized user that theSV URA may be worse than indicated in subframe 1 and that he shall use that SV at his own risk.Bit 19 is an anti-spoof (A-S) flag. A "1" in bit-position 19 indicates that the A-S mode is ON in that SV.Bits 20, 21, and 22 of the HOW provide the ID of the subframe in which that particular HOW is the second word;the ID code shall be as follows:SubframeID Code12340010100111005101IS-GPS-200D7 Dec 200481TLM Word1 = Reserved BitsMSBPreambleTLM Message1 0 0 0 1 0 1 11 2 3 4 5 6 7 8ParityLSB9 10 11 12 131114 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30HOWSolved for bits to preserveparity check with zeros inbits 29 and 30Anti-Spoof Flag“Alert” FlagMSBParityLSBSubframeIDTOW-Count Message(Truncated)1 2 3 4 5 6 7 8 910 11 12 13 14 15 16 17 18 190020 21 22 23 24 25 26 27 28 29 30Figure 20-2.

TLM and HOW FormatsIS-GPS-200D7 Dec 20048220.3.3.3 Subframe 1. The content of words three through ten of subframe 1 are defined below, followed by relatedalgorithms and material pertinent to use of the data.20.3.3.3.1 Subframe 1 Content. The third through tenth words of subframe 1 shall each contain six parity bits astheir LSBs; in addition, two non-information bearing bits shall be provided as bits 23 and 24 of word ten for paritycomputation purposes. The remaining 190 bits of words three through ten shall contain the clock parameters andother data described in the following.The clock parameters describe the SV time scale during the period of validity. The parameters in a data set shallbe valid during the interval of time in which they are transmitted and shall remain valid for an additional period oftime after transmission of the next data set has started.

The timing information for subframes, pages, and data setsis covered in Section 20.3.4.20.3.3.3.1.1 Transmission Week Number. The ten MSBs of word three shall contain the ten MSBs of the 29-bit Zcount as qualified herein. These ten bits shall be a modulo 1024 binary representation of the current GPS weeknumber at the start of the data set transmission interval (see paragraph 3.3.4(b)).

The GPS week number incrementsat each end/start of week epoch. For Block II SVs in long-term extended operations, beginning approximately 28days after upload, the transmission week number may not correspond to the actual GPS week number due to curvefit intervals that cross week boundaries.20.3.3.3.1.2 Code(s) on L2 Channel. Bits 11 and 12 of word three shall indicate which code(s) is (are) commandedON for the L2 channel, as follows:00 =Reserved,01 =P code ON,10 =C/A code ON.IS-GPS-200D7 Dec 20048320.3.3.3.1.3 SV Accuracy. Bits 13 through 16 of word three shall give the URA index of the SV (referenceparagraph 6.2.1) for the unauthorized user. Except for Block IIR/IIR-M SVs in the Autonav mode, the URA index(N) is an integer in the range of 0 through 15 and has the following relationship to the URA of the SV:URA INDEX0123456789101112131415URA (meters)0.002.403.404.856.859.6513.6524.0048.0096.00192.00384.00768.001536.003072.006144.00< URA ≤2.40< URA ≤3.40< URA ≤4.85< URA ≤6.85< URA ≤9.65< URA ≤13.65< URA ≤24.00< URA ≤48.00< URA ≤96.00< URA ≤192.00< URA ≤384.00< URA ≤768.00< URA ≤ 1536.00< URA ≤ 3072.00< URA ≤ 6144.00< URA (or no accuracy prediction is available - unauthorized users areadvised to use the SV at their own risk.)For each URA index (N), users may compute a nominal URA value (X) as given by:•If the value of N is 6 or less, X = 2(1 + N/2),•If the value of N is 6 or more, but less than 15, X = 2(N - 2),•N = 15 shall indicate the absence of an accuracy prediction and shall advise the unauthorizeduser to use that SV at his own risk.For N = 1, 3, and 5, X should be rounded to 2.8, 5.7, and 11.3 meters, respectively.For Block IIR/IIR-M SVs in the Autonav mode, the URA shall be defined to mean “no better than X meters”, with “X”as defined above for each URA indexIS-GPS-200D7 Dec 20048420.3.3.3.1.4 SV Health.