IS-GPS-200F (811524), страница 10
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Time Line Relationship of HOW Message43IS-GPS-200F21 Sep 20114. NOT APPLICABLE44IS-GPS-200F21 Sep 20115. NOT APPLICABLE45IS-GPS-200F21 Sep 20116. NOTES6.1 AcronymsAI-Availability IndicatorAODO-Age of Data OffsetA-S-Anti-SpoofingAutonav-Autonomous NavigationBPSK-Bi-Phase Shift KeyCDC-Clock Differential CorrectionCNAV-Civil Navigationcps-cycles per secondCRC-Cyclic Redundancy CheckCS-Control SegmentDC-Differential CorrectionDb-Power ratio of a signal to a (unmodulated) carrier signal, expressedin decibelsdBi-Decibel with respect to isotropic antennadBW-Decibel with respect to 1 WDN-Day NumberEAROM-Electrically Alterable Read-Only MemoryECEF-Earth-Centered, Earth-FixedECI-Earth-Centered, InertialEDC-Ephemeris Differential Correction46IS-GPS-200F21 Sep 2011EOE-Edge-of-EarthEOL-End of LifeERD-Estimated Range DeviationFEC-Forward Error CorrectionGGTO-GPS/GNSS Time OffsetGNSS-Global Navigation Satellite SystemGPS-Global Positioning SystemGPSW-Global Positioning System WingHOW-Hand-Over WordICC-Interface Control ContractorID-IdentificationIERS-International Earth Rotation and Reference Systems ServiceIODC-Issue of Data, ClockIODE-Issue of Data, EphemerisIRM-IERS Reference MeridianIRP-IERS Reference PoleIS-Interface SpecificationISC-Inter-Signal CorrectionLSB-Least Significant BitLSF-Leap Seconds FutureL2 C-L2 Civil SignalL2 CL-L2 Civil-Long Code47IS-GPS-200F21 Sep 2011L2 CM-L2 Civil-Moderate CodeMCS-Master Control StationMSB-Most Significant BitNAV-NavigationNDUS-Nudet Detection User SegmentNMCT-Navigation Message Correction TableNSC-Non-Standard C/A-CodeNSCL-Non-Standard L2 CL-CodeNSCM-Non-Standard L2 CM-CodeNSY-Non-Standard Y-codeOBCP-On-Board Computer ProgramOCS-Operational Control SystemPPS-Precise Positioning ServicePRN-Pseudo-Random NoiseRF-Radio FrequencyRMS-Root Mean SquareSA-Selective AvailabilitySEP-Spherical Error ProbableSPS-Standard Positioning Servicesps-symbols per secondSS-Space SegmentSSV-Space Service Volume48IS-GPS-200F21 Sep 2011SV-Space VehicleSVN-Space Vehicle NumberTBD-To Be DeterminedTBS-To Be SuppliedTLM-TelemetryTOW-Time Of WeekUE-User EquipmentURA-User Range AccuracyURE-User Range ErrorUS-User SegmentUSNO-U.S.
Naval ObservatoryUTC-Coordinated Universal TimeWGS 84-World Geodetic System 1984WN-Week NumberWNe-Extended Week Number49IS-GPS-200F21 Sep 20116.2 Definitions6.2.1 User Range Accuracy. User Range Accuracy (URA) is a statistical indicator of the GPS ranging accuracyobtainable with a specific signal and SV. URA provides a conservative RMS estimate of the user range error (URE)in the associated navigation data for the transmitting SV. It includes all errors for which the Space and ControlSegments are responsible.
Whether the integrity status flag is 'off' or 'on', 4.42 times URA bounds the instantaneousURE under all conditions with 1-(1e-5) per hour probability (‘legacy’ level of integrity assurance). When theintegrity status flag is 'on', 5.73 times URA bounds the instantaneous URE under all conditions with 1-(1e-8) perhour probability (‘enhanced’ level of integrity assurance). Integrity properties of the URA are specified with respectto the scaled (multiplied by either 4.42 or 5.73 as appropriate) upper bound values of the URA index or to the scaledcomposite of the upper bound values of all component URA indexes.Note #1: URA applies over the transmission interval that is applicable to the NAV data from which the URA is read,for the worst-case location within the satellite footprint.Note #2: The URA for a particular signal may be represented by a single index in the NAV data or by a compositeof more than one index representing components of the total URA.
Specific URA indexes and formulae forcalculating the total URA for each signal are defined in appendix 20 for the LNAV message and appendix 30 for theCNAV message.Note #3: The above integrity assured probability values do not apply if: (a) an alert is issued to the users before theinstantaneous URE exceeds either of the scaled URA bounds, or (b) an alert is issued to the users no more than 8.0seconds after the instantaneous URE exceeds the 4.42 times URA bound, and (c) if the integrity status flag is 'on'and an alert is issued to the users no more than 5.2 seconds after the instantaneous URE exceeds the 5.73 times URAbound. In this context, an "alert" is defined as any indication or characteristic of the conveying signal, as specifiedelsewhere in this document, which signifies to users that the conveying signal may be invalid or should not be used,such as the health bits not indicating operational-healthy, broadcasting non-standard code, parity error, etc.50IS-GPS-200F21 Sep 20116.2.1.1 User Differential Range Accuracy.
User Differential Range Accuracy (UDRA) is a statistical indicator ofthe GPS ranging accuracy obtainable with a specific signal and SV after the application of the associated differentialcorrections (DC parameters). UDRA provides a conservative RMS estimate of the differential user range errors inthe navigation data for that satellite. It includes all errors for which the Space and Control Segments are responsible.6.2.2 SV Block Definitions.The following block definitions are given to facilitate discussion regarding thecapability of the various blocks of GPS satellites to support the SV-to-US interface.6.2.2.1 Developmental SVs.
The original concept validation satellites developed by Rockwell International anddesignated as satellite vehicle numbers (SVNs) 1-11 are termed "Block I" SVs. These SVs were designed to provide3-4 days of positioning service without contact from the CS. These SVs transmitted a configuration code of 000(reference paragraph 20.3.3.5.1.4). There are no longer any active Block I SVs in the GPS constellation. The lastBlock I SV was decommissioned in 1995.6.2.2.2 Operational SVs. The operational satellites are designated Block II, Block IIA, Block IIR, Block IIR-M,Block IIF and GPS III SVs.
Characteristics of these SVs are provided below. Modes of operation for these SVs andaccuracy of positioning services provided are described in paragraphs 6.3.2 through 6.3.4. These SVs transmitconfiguration codes as specified in paragraph 20.3.3.5.1.4. The navigation signal provides no direct indication ofthe type of the transmitting SV.6.2.2.2.1 Block II SVs. The first block of full scale operational SVs developed by Rockwell International aredesignated as SVNs 13-21 and are termed "Block II" SVs.
These SVs were designed to provide 14 days ofpositioning service without contact from the CS.6.2.2.2.2 Block IIA SVs. The second block of full scale operational SVs developed by Rockwell International aredesignated as SVNs 22-40 and are termed "Block IIA" SVs. These SVs are capable of providing 60 days ofpositioning service without contact from the CS.6.2.2.2.3 Block IIR SVs.The block of operational replenishment SVs developed by Lockheed Martin aredesignated as SVNs 41-61 and are termed "Block IIR" SVs.
These SVs have the capability of storing at least 60days of navigation data with current memory margins, while operating in a IIA mode, to provide positioning servicewithout contact from the CS for that period. (Contractual requirements for these SVs specify transmission of correctdata for only 14 days to support short-term extended operations while in IIA mode.) The IIR SV will provide aminimum of 60 days of positioning service without contact from the CS when operating in autonomous navigation(Autonav) mode.6.2.2.2.4 Block IIR-M SVs.
The subset of operational replenishment SVs developed by Lockheed Martin which are“Modernized” configuration of “Block IIR” SVs are termed “Block IIR-M”.51IS-GPS-200F21 Sep 20116.2.2.2.5 Block IIF SVs. The block of operational replenishment SVs developed by Boeing are designated as SVNs62-73 and are termed “Block IIF” SVs. This is the first block of operational SVs that transmit the L5 Civil signal.These SVs will provide at least 60 days of positioning service without contact from the CS.6.2.2.2.6 GPS III SVs.
The block of operational replenishment SVs are designated as SVNs 74-105. This is the firstblock of operational SVs that transmit the L1C signal.These SVs will provide at least 60 days of positioningservice without contact from the CS.6.2.3 Operational Interval Definitions. The following three operational intervals have been defined. These labelswill be used to refer to differences in the interface definition as time progresses from SV acceptance of the lastnavigation data upload.6.2.3.1 Normal Operations.
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