IS-GPS-200F (811524), страница 13
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PRN allocations do not exist for numbers 64through 158 for L2 CM-/L2 CL-code. Any assignment of a L2 CM-/L2 CL-code PRN number and its codesequence pair for any additional SV and/or other L2 signal applications will be selected from the sequences of Table6-II and will be approved, controlled, and managed by the GPS Directorate.64IS-GPS-200F21 Sep 2011Table 6-II.PRNSignalNo.159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190Additional L2 CM-/L2 CL-Code Phase Assignments (sheet 1 of 2)Initial Shift Register State (Octal)L2 CML2 CL604055104157065232013305707603552017230461355603653437652346475743107103401521277167335110014013575362051132617753265216363634755561123365304033625025543054420334415473671662364360373446602417564100000526452226631300113752074706134401041352546664630154276524255714720530714051771044526647End Shift Register State (Octal)L2 CM *L2 CL **605253024063314262066073422737276117737243704067557532227354537704765502044746712720535263733541364270060042737176640133776704005645427704321074137740372056375464704374004216320123011322115761050112725304036721320336443462103510466244745522652373417061225526762047614504034730440453073141***425373114427153064310366577623710414252761705050174703050301454416652040050301251744136527633772375007131446142007172655543571031272346203260313226613112736560607011741374765056120262725266013051476144541215534125243250001521276000566447447071000202044751430577136741270257252440757666513044547544707116115412264037223755032403114174671505575606261015223023120370035547516101304044115766704125517406332330506446631743702511022623276704221045372577721105175230760701311737141001227627616245154134040015760002154472301767766226475246733673015602507667753362551746265601036253206Short cycled period = 10230Short cycled period = 76725065IS-GPS-200F21 Sep 2011Table 6-II.PRN SignalNo.191192193194195196197198199200201202203204205206207208209210Additional L2 CM-/L2 CL-Code Phase Assignments (sheet 2 of 2)Initial Shift Register State (Octal)L2 CML2 CL207164322262120161204244652202133131714351204657127260130567507670517677607275514045413633212645405613700455706202440705056276020373522746013617132720621434015513566721727140633660533654510377016461235525312507056307221720061520470122603764120145604016051237167033326347534627074645230164000171400022715417135471311137422057714426456640724672501254540513322453***End Shift Register State (Octal)L2 CM *L2 CL **606512137734247645415505547705146647006215430371216176645502771455175106127161032470332401252026355113771472754447142627405712325721745056714616706035241173076740145721746465052527202512772701234023722043377240751052375674043166677056123055362707017665437503241275605155376333266467523556144132537451024205722446427412376261441570172063217710110320656113765506Short cycled period = 10230Short cycled period = 76725066IS-GPS-200F21 Sep 20116.3.8 Pre-Operational Use.
Before any new signal or group of signals (e.g., L2C, L5, M, L1C, etcetera) is declaredoperational, the availability of and/or the configuration of the broadcast signal or group of signals may not complywith all requirements of the relevant IS or ICD. For example, the pre-operational broadcast of L2C signals from theIIR-M satellites did not include any NAV or CNAV data as required by IS-GPS-200.
Pre-operational use of anynew signal or group of signals is at the users own risk.6.4 Operational Protocols.6.4.1 Lower PRN Numbers Versus Upper PRN Numbers Many existing user receivers are only compatible withprior versions of this IS where the PRN numbers and corresponding PRN code sequences were limited to the lowerrange of 1 - 32. To maintain backwards compatibility with these receivers (and promote backwards utility), the CSwill endeavor to operate as robust a constellation as practical using just the lower range of PRN numbers. The upperrange of PRN numbers (33 - 63) is intended as an enhancement for modernized receivers which are compatible withboth the lower PRN numbers and the upper PRN numbers. When feasible, the CS will endeavor to operate at leastone satellite using an upper PRN number to serve as a source of almanac data for satellites using the upper range ofPRN numbers.6.4.2 PRN Number Consistency For a given satellite, the same PRN number will be assigned to all operationalsignals (signals modulated by standard PRN code with data that indicates the signal health is OK).6.4.3 PRNs 33 and 37 PRN 33 should not be used by satellites because of its prior use in specialized groundapplications.
PRN 37 should not be used by satellites until after PRN 37 is no longer needed for SATZAP purposes.6.4.4 PRNs 33 through 63 The CS must ensure that satellites broadcasting PRNs 33 through 63 are synchronized toGPS time to avoid conflict with specialized ground applications.6.4.5 Health Code Setting of ‘11110’ For backward compatibility reasons, the SV signal component health codesetting of ‘11110’ is anticipated for potential use only with satellites broadcasting PRNs 33 through 63.67IS-GPS-200F21 Sep 201110. APPENDIX I.
LETTERS OF EXCEPTION10.1 Scope. Approval of this document, as well as approval of any subsequent changes to the document, can becontingent upon a "letter of exception". This appendix depicts such "letters of exception" when authorized by theGPS Directorate.10.2 Applicable Documents. The documents listed in Section 2.0 shall be applicable to this appendix.10.3 Letters of Exception. Any letter of exception which is in force for the revision of the IS is depicted in Figure10.3-1 - 10.3-8.68IS-GPS-200F21 Sep 2011Figure 10.3-1. Letters of Exception.69IS-GPS-200F21 Sep 2011Figure 10.3-2. Letters of Exception (continued)70IS-GPS-200F21 Sep 2011Figure 10.3-3.
Letters of Exception (continued)71IS-GPS-200F21 Sep 2011Figure 10.3-4. Letters of Exception (continued).72IS-GPS-200F21 Sep 2011Figure 10.3-5. Letters of Exception (continued)73IS-GPS-200F21 Sep 2011Figure 10.3-6. Letters of Exception (continued).74IS-GPS-200F21 Sep 2011Figure 10.3-7. Letters of Exception (continued).75IS-GPS-200F21 Sep 2011Figure 10.3-8. Letters of Exception (continued).76IS-GPS-200F21 Sep 201120. APPENDIX II. GPS NAVIGATION DATA STRUCTURE FOR LNAV DATA, D(t), FOR PRN 1-3220.1 Scope. This appendix describes the specific legacy navigation (LNAV) data structure denoted by data IDnumber 2 for the lower set of PRN numbers (PRN 1-32).
This data ID number, when transmitted as part of theLNAV data, shall be represented by the two-bit binary notation as 01. Data ID number 1 is no longer in use. TheLNAV data structure for the lower set of PRN numbers is denoted as LNAV-L. The LNAV data structure for theupper set of PRN numbers (LNAV-U) is described in Appendix IV.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 Appendix tothe extent specified herein.SpecificationsFederalNoneMilitaryNoneOther Government ActivityNoneStandardsFederalNoneMilitaryNoneOther PublicationsGP-03-001 (GPS Interface Control Working Group Charter)20.2.2 Non-Government Documents.
In addition to the documents listed in paragraph 2.2, the following documentsof the issue specified contribute to the definition of the NAV data related interfaces and form a part of this Appendixto the extent specified herein.SpecificationsNoneOther PublicationsNone77IS-GPS-200F21 Sep 201120.3 Requirements.20.3.1 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 the L2CM 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 1500 bitlong 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. The25 versions of subframes 4 and 5 shall be referred to herein as pages 1 through 25 of each subframe.
Each subframeshall 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 HOW 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.
GPS IIISVs have the capability to support operation for at least 60 days without contact from the CS. Alternating ones andzeros will be transmitted in words 3 through 10 in place of the normal NAV data whenever the SV cannot locate therequisite valid control or data element in its on-board computer memory. The following specifics apply to thisdefault action: (a) the parity of the affected words will be invalid, (b) the two trailing bits of word 10 will be zeros(to allow the parity of subsequent subframes to be valid -- reference paragraph 20.3.5), (c) if the problem is the lackof a data element, only the directly related subframe(s) will be treated in this manner, (d) if a control element cannotbe located, this default action will be applied to all subframes and all subframes will indicate ID = 1 (Block II/IIAonly) (i.e., an ID-code of 001) in the HOW (reference paragraph 20.3.3.2) (Block IIR/IIR-M, IIF, and GPS III SVsindicate the proper subframe ID for all subframes).
Certain failures of control elements which may occur in the SVmemory or during an upload will cause the SV to transmit in non-standard codes (NSC and NSY) which wouldpreclude normal use by the US. Normal NAV data transmission will be resumed by the SV whenever a valid set ofelements becomes available.Block 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.
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