Интерфейсный документ GPS, страница 10

Formal request for cost and schedule impacts should comethrough the JPO Contracting Officer.To change from -161.4 dBW to -160.0 dBW would have to be analyzed and coordinated betweenLockheed Martin and ITT. If such a change were technically possible, there would be impacts to L-Bandlevel testing, SV level testing, test scripts, Specs, OOH, and various ICDs. These impacts would be inboth cost and schedule.Figure 10-1.

Letters of Exception.IS-GPS-200D7 Dec 200459GPS IIR-CM-MOD-147Page 2Currently, there is an ongoing effort between Lockheed Martin, Boeing, Arinc, Aerospace, and the JPOconcerning signal flexibility under the ConOps study. Lockheed Martin recommends, based on theoutcome and direction of this effort, that an impact to the ICD-200 change be included in the resultingrequest for ROMs for Flex Power implementation.Note that if Lockheed Martin has taken earlier exception to a change in any requirements in a previousrevision of this document, Lockheed Martin continues to take exception to that change.

A letter explicitlystating that the exception is no longer valid will accomplish the retraction of an exception.Should you have any questions, please contact Martin O’Connor at (610) 354-7866 for technicalconcerns, or the undersigned at (610) 354-7989 for contractual matters.Very truly yours,LOCKHEED MARTIN CORPORATIONSignature on fileBrent B.

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.