Novatel OM-20000077 user manual Appendix E, Ttff and Satellite Acquisition, Time-To-First-Fix Ttff

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Appendix E

TTFF and Satellite Acquisition

E.1 Time-To-First-Fix (TTFF)

The receiver enters Navigation mode, see Operational States on Page 31, and provides valid outputs in less than 50 seconds after completion of the self-test and the following initialization criteria have been met:

1.Valid time (±10 minutes) and position data (±100 km) from actual position

2.Valid almanac data (less than a year old)

3.At least 4 satellites greater than 5° elevation above the horizon

4.HDOP < 6

The time allowed for self-test and device initialization is less than 5 seconds.

In the case where the following additional conditions are met, the TTFF is reduced to less than 30 seconds:

Unit has not been off for more than a week before nominal power is re-applied

Last navigation fix occurred within the last 2 hours

Valid ephemeris data (less than 4 hours old) for at least 5 satellites

With no initialization, the time from power application to valid navigation output is typically less than 3 minutes.

E.2 Re-Acquisition

Re-acquisition is the resumption of tracking and measurement processing.

There is no disruption of navigation data output when a satellite signal is lost unless there is a power interruption for a period of less than or equal to 200 ms. Also, the receiver re-acquires the satellite signal within 0.3 seconds after satellite visibility has been restored.

When a satellite signal is lost due to signal masking, the signal is typically re-acquired within 2-3 seconds after the satellite signal meets the minimum input levels. The vehicle dynamics during the masking period are assumed to be less than or equal to 0.5 g acceleration and 100 m/s velocity.

When total signal masking occurs, navigation resumes within 3-5 seconds of a Navigation mode criteria being met.

The receiver is capable of acquiring satellite signals with a minimum input carrier-to-noise density ratio (C/N0) to the correlator of 34 dB-Hz. Once a signal has been acquired, the receiver is capable of tracking satellite signals with a minimum input carrier-to-noise density ratio (C/N0) to the correlator of 31 dB-Hz.

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Contents Superstar Proprietary Notice Table of Contents Appendices Tables Figures Software License Software License Contact Information Firmware UpdatesElectrostatic Discharge CE Notice Warranty Policy Congratulations Scope Related PublicationsRelated Publications Superstar II GPS Card IntroductionIntroduction Chapter FlexPak-SSIIChapter Introduction Radio Frequency RF Section Receiver SpecificationsPhysical Characteristics System ArchitectureGPS Antenna Enclosure and Wiring HarnessPrincipal Power Supply Optional LNA Power SupplyTypical System Configuration Reference Description InstallationSerial Connection Chapter InstallationElectrostatic Discharge Equipment InterconnectionAntenna Location Installation ConsiderationsPower Connection Installation ChapterBase Station and Rover Units Separation Connectors and Connector Pins Assignment1 J1 Interface and Power Connector Data LinkSerial Data Interface RF Connector J2RF Input Preamplifier Power Pass-Through Antenna SupplyProtocol Selection and Non Volatile Memory Memory Back-UpDiscretes IP2 and IP3 functions Use of DiscretesDefault Configuration Non Volatile MemoryNon-Volatile Memory Data Description Reference Installation OverviewOperation Typical Operational Configuration Reference DescriptionOperation Chapter Serial Port Default SettingsCommunications with the Receiver Getting StartedChapter Operation Power-Up InformationBoot Information Operational InformationConfigurable Parameters Data RequestsReceiver States Self-Test Mode Built-In Status Tests Dead-Reckoning ModeDatum Support Message Formats RTCM-Format MessagesRTCM1 Differential GPS Corrections Fixed RTCM2 Delta Differential GPS Corrections Fixed RTCM9 Partial Satellite Set Differential CorrectionsChapter Message Formats Message Formats Chapter Nmea Format Data MessagesGPS System Errors Positioning Modes of OperationSingle-Point or Autonomous Positioning Modes of Operation Chapter Satellite-Based Augmentation System SbasSbas Receiver Sbas MessagesChapter Positioning Modes of Operation Positioning Modes of Operation Chapter Cable Lengths Vs. Gain TroubleshootingTroubleshooting Chapter Technical Specifications Appendix aSuperstar II Family Performance Output Messages Technical Specifications Appendix aMechanical Drawing Appendix a Technical SpecificationsJ1 Interfaces and Power Connector Pin Assignment Connector Pin AssignmentO Signals Voltage Limits 3 I/O Electrical CharacteristicsAppendix B FlexPak-SSII SpecificationsPort Pin-Outs Status IndicatorsAppendix B FlexPak-SSII Specifications FlexPak Status IndicatorsFlexPak-SSII Specifications Appendix B Automobile Power Adapter Cable NovAtel part numberCables FlexPak 13-Pin Serial Cable 3.2 13-Pin Deutsch to DB9 Serial Cable NovAtel part numberDescription Setup and OperationNormal Setup Development KitDifferential GPS Setup Dgps Setup with the FlexPak-SSIIStarView Software Installation Cable Selection Antenna SpecificationsCoaxial Cable Specifications Appendix CTypical Current Consumption Versus Antenna Gain Antenna Specifications Appendix CGeodetic Active Antenna Antenna Gain Depending on Cable Length RequiredRecommended Geodetic Active Antennas Appendix C Antenna SpecificationsActive Antenna Passive AntennaGPS Antenna 201-990146-716 MCX, +12 dB Passive Antenna Specifications Patch ElementGPS Antenna 201-990147-606 +26 dB Antenna Specifications Appendix C Standards/References Appendix DRe-Acquisition Appendix ETtff and Satellite Acquisition Time-To-First-Fix TtffSystem Requirements Utility InstallationAppendix F Updating Receiver FirmwareStarting Software and Options Update Registration Key AcceptedUpdating Receiver Firmware Appendix F Appendix F Updating Receiver Firmware Programming SuccessSpace Segment Appendix GGPS Overview GPS System DesignAppendix G GPS Overview Height RelationshipsControl Segment User SegmentGPS Overview Appendix G GPS PositioningAccuracy versus Precision1 Single-Point vs. Relative PositioningMultipath Static vs. Kinematic PositioningReal-time vs. Post-mission Data Processing Consequences of Multipath Reception Why Does Multipath Occur?Antenna Site Selection Hardware Solutions For Multipath ReductionAntenna Designs GPS Signal Multipath vs. Increased Antenna HeightGPS Overview Appendix G Glossary of Terms Appendix HGlossary of Terms Appendix H Appendix H Glossary of Terms Glossary of Terms Appendix H Acronyms AppendixAcronyms Appendix Appendix Acronyms Index Index GEO, SbasIndex Index OM-20000077 Rev 2004/03/11