Интерфейсный документ GPS, страница 10

Achee IIGPS Block IIR Deputy Program Directorxc:Capt. K. EggehornMary GuyesSoon Yi, ARINCJ. Windfelder, DCMCFigure 10-1. Letters of Exception (continued).IS-GPS-200D7 Dec 200460Lockheed Martin Space Systems CompanySpace & Strategic MissilesValley Forge OperationsP.O. Box 8555 Philadelphia, PA 1910127 September 2004GPS IIR-CM-3023, Rev AARINC2250 E. Imperial Highway, Suite 450El Segundo, CA 90245-3546Attention:Mr. Soon K. YiSubject:Review of IS-GPS-200 Rev DReference:1)2)Contract F04701-89-C-0073IS-GPS-200D, dated 09 July 2004Dear Mr.

Yi:Lockheed Martin Space Systems Company has reviewed the subject version of IS-GPS-200D, dated 09July 2004. It is Lockheed Martin’s understanding that the JPO and ARINC are in the process ofincorporating major changes to ICD-200C, eliminating multiple Letters of Exception, and change theInterface Control Document to an Interface Specification (IS).

With this in mind, Lockheed Martin isrescinding all previous letters of exception:1.GPS IIR-CM-1046, dated 17 August 19942.GPS IIR-CM-MOD-0097, dated 08 May 20023.GPS IIR-CM-2837, dated 26 May 20034.GPS IIR-CM-MOD-0177, dated 16 March 2004Lockheed Martin would like to establish this correspondence for the review of IS-GPS-200 as thebaseline letter of exception. Lockheed Martin is taking exception to:1.L2CNAV2.IIR-M L2C Signal Power, as defined in Table 3-VThe original Letter of Exception, dated 09 September 2004 listed IODC as an exception. LockheedMartin has been able to verify this exception no longer exists. This revision to the LOE should thereforebe used in it’s place. Specific reasoning for these exceptions are documented in the attached table.Lockheed Martin is also submitting technical comments identified herein. If this document is approved atJPO CCB, LMSSC will expect a letter from JPO requesting cost and schedule impacts to implement theseout-of-scope requirements on the IIR and IIR-M contracts.Per discussions with ARINC, telecons with the JPO, and the IS-200D review directions, it is LockheedMartin’s understanding that the once this document is Configuration Controlled by the JPO, ICD-200 willbe removed from Lockheed Martin’s contract with the government and replace with IS-200.

Theapproved IS-200 will contain this LOE and Lockheed Martin will be notified in writing as to changes thatoccurred as part of the CCB process for concurrence to said changesFigure 10-1. Letters of Exception (continued).IS-GPS-200D7 Dec 200461Should you have any questions, please contact Marty O’Connor at (610) 354-7866 for technical concerns,or the undersigned at (610) 354-2569 for contractual matters.Very truly yours,LOCKHEED MARTIN CORPORATIONSignature on filePaul E.

Ruffo, CPCMManager of ContractsGPS Block IIR, IIR-M, IIIxc:Mary GuyesA. TraderJ. Windfelder, DCMACapt. Brian KnightFigure 10-1. Letters of Exception (continued).IS-GPS-200D7 Dec 200462Figure 10-1. Letters of Exception (continued).IS-GPS-200D7 Dec 200463Figure 10-1. Letters of Exception (continued).IS-GPS-200D7 Dec 20046420. APPENDIX II. GPS NAVIGATION DATA STRUCTURE FOR DATA, D(t)20.1 Scope. This appendix describes the specific GPS navigation (NAV) data structure denoted as D(t).

Whentransmitted as part of the NAV data, D(t), the specific data structure of D(t) shall be denoted by data ID number 2,represented by the two-bit binary notation as 01.20.2 Applicable Documents.20.2.1 Government Documents. In addition to the documents listed in paragraph 2.1, the following documents ofthe issue specified contribute to the definition of the NAV data related interfaces and form a part of this Appendixto the extent specified herein.SpecificationsNoneStandardsNoneOther PublicationsNone20.2.2Non-Government Documents.In addition to the documents listed in paragraph 2.2, the followingdocuments of the issue specified contribute to the definition of the NAV data related interfaces and form a part ofthis Appendix to the extent specified herein.SpecificationsNoneOther PublicationsNoneIS-GPS-200D7 Dec 200465(This page intentionally left blank.)IS-GPS-200D7 Dec 20046620.3 Requirements20.3.1 Data Characteristics.

The data stream shall be transmitted by the SV on the L1 and L2 channels at a rate of50 bps. In addition, upon ground command, the data stream shall be transmitted by the Block IIR-M SV on theL2 CM channel at a rate of 25 bps using FEC encoding resulting in 50 sps.20.3.2 Message Structure. As shown in Figure 20-1, the message structure shall utilize a basic format of a 1500bit long frame made up of five subframes, each subframe being 300 bits long.

Subframes 4 and 5 shall besubcommutated 25 times each, so that a complete data message shall require the transmission of 25 full frames.The 25 versions of subframes 4 and 5 shall be referred to herein as pages 1 through 25 of each subframe. Eachsubframe shall consist of ten words, each 30 bits long; the MSB of all words shall be transmitted first.Each subframe and/or page of a subframe shall contain a telemetry (TLM) word and a handover word (HOW), bothgenerated by the SV, and shall start with the TLM/HOW pair.The TLM word shall be transmitted first,immediately followed by the HOW.

The latter shall be followed by eight data words. Each word in each frameshall contain parity (reference Section 20.3.5).Block II and IIA SVs are designed with sufficient memory capacity for storing at least 60 days of uploaded NAVdata. However, the memory retention of these SVs will determine the duration of data transmission. Block IIR SVshave the capability, with current memory margin, to store at least 60 days of uploaded NAV data in the Block IIAmode and to store at least 60 days of CS data needed to generate NAV data on-board in the Autonav mode.Alternating ones and zeros will be transmitted in words 3 through 10 in place of the normal NAV data whenever theSV cannot locate the requisite valid control or data element in its on-board computer memory. The followingspecifics apply to this default action: (a) the parity of the affected words will be invalid, (b) the two trailing bits ofword 10 will be zeros (to allow the parity of subsequent subframes to be valid -- reference paragraph 20.3.5), (c) ifthe problem is the lack of a data element, only the directly related subframe(s) will be treated in this manner, (d) ifa control element cannot be located, this default action will be applied to all subframes and all subframes willindicate ID = 1 (Block II/IIA only) (i.e., an ID-code of 001) in the HOW (reference paragraph 20.3.3.2) (BlockIIR/IIR-M and IIF SVs indicate the proper subframe ID for all subframes).

Certain failures of control elementswhich may occur in the SV memory or during an upload will cause the SV to transmit in non-standard codes (NSCand NSY) which would preclude normal use by the US. Normal NAV data transmission will be resumed by the SVwhenever a valid set of elements becomes available.IS-GPS-200D7 Dec 200467Block II/IIA SVs are uploaded with a minimum of 60 days of NAV data. However, the EAROM retentivity forBlock II SVs is designed and guaranteed for only 14 days.

Therefore, Block II SV memory is most likely to failsometime during long-term extended operations after repeated write operations. In the case of memory failure, theSV will transmit alternating ones and zeros in word 3-10 as specified in the above paragraph. The EAROMretentivity for Block IIA SVs is designed and guaranteed for at least 60 days.The memory retentivity for the Block IIR/IIR-M/IIF SVs is designed and guaranteed for at least 60 days.Although the data content of the SVs will be temporarily reduced during the upload process, the transmission ofvalid NAV data will be continuous.

The data capacity of specific operational SVs may be reduced to accommodatepartial memory failures.IS-GPS-200D7 Dec 200468DIRECTION OF DATA FLOW FROM SV150 BITSWORD 1MSB FIRST3 SECONDSWORD 2WORD 3WORD 4WORD 571SUBFRAMENO.PAGENO.131TLM1N/A22 BITSHOWC P73 77 836191121WNt P22 BITS23 BITS***P10BITSPL2 P DATA FLAG - 1 BITC/A OR P ON L2 - 2 BITSURA INDEX - 4 BITSSV HEALTH - 6 BITS2 MSBsIODC - 10 BITS TOTALDIRECTION OF DATA FLOW FROM SV150 BITSWORD 61N/A18124 BITS***P16BITS***WORD 8197TGDMSB FIRST3 SECONDSWORD 7151P24 BITS***WORD 9211 219P8 BITSWORD 10241toc16 BITSPaf28BITS8 LSBs271af116 BITSPaf0t P22 BITSIODC - 10 BITS TOTAL*** 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 1 of 11)IS-GPS-200D7 Dec 200469DIRECTION OF DATA FLOW FROM SV150 BITSWORD 1SUBFRAMENO.PAGENO.WORD 21WORD 331TLM261HOWC PN/At22 BITSMSB FIRST3 SECONDSP22 BITSWORD 469IODE8BITS91WORD 5107121∆nCrs8BITSP16 BITS16 BITS24 BITSPMSBsPLSBsM0 - 32 BITS TOTALDIRECTION OF DATA FLOW FROM SV150 BITSWORD 6151CUC2N/A16 BITS8BITSMSBse - 32 BITS TOTALWORD 7WORD 8181167P21124 BITSMSB FIRST3 SECONDSPCUS16 BITSLSBsWORD 92412278BITS27124 BITSPP287toetP16 BITSMSBsA - 32 BITS TOTALWORD 10LSBsFIT INTERVAL FLAG - 1 BITAODO - 5 BITSP = 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 2 of 11)IS-GPS-200D7 Dec 200470DIRECTION OF DATA FLOW FROM SV150 BITSWORD 1SUBFRAMENO.PAGENO.WORD 21HOWt22 BITSCicPWORD 5918BITS16 BITS22 BITSWORD 47761C PN/AWORD 331TLM3MSB FIRST3 SECONDS24 BITSPMSBsN/AWORD 7PWORD 8WORD 9211Crc16 BITSWORD 10241271•8BITSP24 BITSΩP24 BITSMSBsLSBsMSB FIRST3 SECONDS18124 BITSPi0 - 32 BITS TOTAL150 BITS38BITSLSBsDIRECTION OF DATA FLOW FROM SV151CisP16 BITSΩ0 - 32 BITS TOTALWORD 6137121LSBsPIODE8BITS279IDOT14BITStPω - 32 BITS TOTALi0 - 32 BITS TOTALP = 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 3 of 11)IS-GPS-200D7 Dec 200471DIRECTION OF DATA FLOW FROM SV150 BITSWORD 1SUBFRAMENO.5PAGENO.MSB FIRST3 SECONDSWORD 2WORD 3WORD 4WORD 561131TLM1THRU246369HOWeC Pt22 BITS91P22 BITS16 BITStoaP8BITS99121δi•ΩP16 BITS8PBITS16 BITSDATA ID - 2 BITSSV ID - 6 BITSSV HEALTHDIRECTION OF DATA FLOW FROM SV150 BITSWORD 6WORD 715151THRU24WORD 8181A24 BITSPWORD 9211Ω0MSB FIRST3 SECONDS241ωP24 BITSWORD 10P24 BITS271M0279290t PP24 BITS8 MSBs3 LSBsaf0 - 11 BITS TOTALaf1 - 11 BITS TOTALP = 6 PARITY BITSt = 2 NONINFORMATION BEARING BITS USED FOR PARITY COMPUTATION (SEE PARAGRAPH 20.3.5)C = TLM BITS 23 AND 24 WHICH ARE RESERVEDNOTE: PAGES 2, 3, 4, 5, 7, 8, 9 & 10 OF SUBFRAME 4 HAVE THE SAME FORMAT AS PAGES 1 THROUGH 24 OF SUBFRAME 5Figure 20-1.

Data Format (sheet 4 of 11)IS-GPS-200D7 Dec 200472DIRECTION OF DATA FLOW FROM SV150 BITSWORD 1SUBFRAMENO.PAGENO.WORD 2WORD 3WORD 4WORD 561131TLM5MSB FIRST3 SECONDS63HOWC P25t22 BITS6991toa WNa88BITS BITSP22 BITSP121SV HEALTH6 BITS/SVSV SV SV SV1234PSV HEALTH6 BITS/SVSV SV SV SV5678PDATA ID - 2 BITSSV (PAGE) ID - 6 BITSDIRECTION OF DATA FLOW FROM SV150 BITSWORD 6WORD 7151525WORD 8181SV HEALTH6 BITS/SVSV SV SV SV9 10 11 12SV HEALTH6 BITS/SVPSV SV SV SV13 14 15 16MSB FIRST3 SECONDS211SV HEALTH6 BITS/SVPSV SV SV SV17 18 19 20WORD 9WORD 10271 277241SV HEALTH6 BITS/SVPSV SV SV SV21 22 23 24P16 BITS **tP6 BITS ***** 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.