Novatel OM-20000122 user manual Azimuth Sources on a Span System, Course Over Ground

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Chapter 3

SPAN-CPT Operation

 

 

The rotation parameters can be saved in NVM for use on startup in case a fast alignment is required in the future. Each time the SPAN-CPT is re-mounted, this calibration should be performed again. See System Start-Up and Alignment Techniques on page 27 for details on alignment.

parameters present and a kinematic alignment is NOT possible. Therefore this command should only be entered after the system has performed either a static or kinematic alignment and has a valid INS solution.After the RVBCALIBRATE ENABLE command is entered, there are no vehicle body rotation

between the SPAN-CPT and vehicle frames. The offsets are used when aligning the system while in motion (see System Start-Up and Alignment Techniques on page 27). The angular offset values are not applied to the attitude output, unless the

APPLYVEHICLEBODYROTATION command is enabled.

3.4.4SPAN-CPT Wheel SensorThe solved rotation values are used only for a rough estimate of the angular offsets

The SPAN-CPT system supports wheel sensor inputs, integrated via the SPAN-CPT. The SPAN-CPT accepts TTL-level input pulses from a wheel sensor through the multi-pin connector. See Appendix A, Technical Specifications on page 48 for specifications on the wheel sensor interface.

3.4.4.1Wheel Sensor Update Logic

The wheel sensor information is sent to the SPAN-CPT along with the raw IMU data.

The SPAN filter uses sequential TIMEDWHEELDATA logs to compute a distance traveled between update intervals (1 Hz). This information is used to constrain free inertial drift during times of poor GNSS visibility. The filter also contains a state for modeling the circumference of the wheel as it may change due to hardware changes or environmental conditions.

The modeled wheel circumference is available in the WHEELSIZE log. Information on how the wheel sensor updates are being used is available in the INSUPDATE log.

3.5Azimuth Sources on a SPAN System

The SPAN system use three different methods to calculate the azimuth.

•Course Over Ground

•Inertial Azimuth

•Align Azimuth

3.5.1Course Over Ground

The course over ground azimuth is determined using the position delta between two position solutions computed by the GNSS receiver. This is the simplest way to compute an azimuth and is done using either the GNSS solution or the INS solution. This method does not work when the vehicle is stationary as any position difference is due to position error and the computed azimuth is meaningless.

Course over ground azimuth is of greatest advantage in aerial or marine environments where the actual direction of travel may not match the forward axis of the aircraft/boat due to winds or currents. This effect is known as the crab angle. Course over ground azimuth is a great way to compute the offset if another means of computing the vehicle azimuth are available.

Course over ground azimuths are available in several different velocity logs. See Table 5, Logs with Azimuth data on page 31.

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SPAN-CPT User Manual Rev 8

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Contents SPAN-CPT Warranty Return instructions Proprietary NoticeTable of Contents Technical Specifications Figures Tables NovAtel Knowledge Base Before Contacting Customer Support Contact InformationFCC Notices Industry CanadaCE Notice Weee Notice Lightning Protection Installation and Grounding ProcedureWhat is the hazard? Hazard ImpactPrimary and Secondary Lightning Protection Ref # Description Introduction Fundamentals of GNSS+INSSystem Components Related Documents and InformationConventions Manuals SPAN-CPT InstallationRequired Equipment SPAN-CPT HardwareHardware Set Up Typical SPAN-CPT Set Up Radio COM2Mount the Antenna Mount the SPAN-CPTConnect Power Connect the Gnss AntennaConnect the I/O Strobe Signals Battery Isolator Auxiliary Vehicle MainBatteryConnect a Computer to the SPAN-CPT Can Bus Odometer ConnectionOdometer Requirements Cable Modification for Kistler WPT Cable Cable Modification for SPAN-CPT CableSPAN-CPT Operation Definition of Reference Frames Within SpanLocal Level Frame Span Body Frame Full Mapping DefinitionsEnclosure Frame Vehicle FrameCommunicating with the SPAN-CPT System Use NovAtel Connect to CommunicateChapter SPAN-CPT Operation Span IMU Configuration Software ConfigurationGnss Configuration SPAN-CPT Configuration with NovAtel ConnectReal Time Operation System Start-Up and Alignment Techniques AsciiDefault Kinematic Alignment SetimuorientationNavigation Mode Manual AlignmentDual Antenna Alignment Wheel Sensor Update Logic Azimuth Sources on a Span SystemCourse Over Ground Inertial Azimuth Align AzimuthLogs with Azimuth data Solution Parameters Data Collection Logging Restriction Data Collection for Post-ProcessingVariable Lever Arm Enabling L-BandNovAtel Correct with TerraStar Veripos Marine Subscriptions OmniSTARChapter SPAN-CPT Operation Installation SPAN-CPT Dual-AntennaChapter SPAN-CPT Dual-Antenna Configuring Span with Align on SPAN-CPTPower Supply SecondaryAlignment on a Moving Vessel Aided Transfer Alignment Alignment on a Stationary Vehicle Aided Static AlignmentUnaided Alignment Span Align Attitude Updates Automatic Alignment Mode Automatic Alignment defaultFirmware Updates and Model Upgrades Firmware UpdatesNovAtel Firmware and Software Authorization Code Model UpgradesUpdating or Upgrading Using the WinLoad Utility Transferring Firmware FilesTypes of Firmware Files Using the WinLoad Utility Open a File to DownloadUpdating using SoftLoad Commands Searching for CardWorking with S-Records Softloadsrec S-RECORDUpgrading Using the Auth Command Key Firmware CommandsUpgrade Procedure Hardware Specification for SPAN-CPT Technical SpecificationsSPAN-CPT Technical Specifications KVH IMU Sensor SpecificationsElectrical and Environmental Specifications Power SpecificationsSPAN-CPT Mechanical Drawings SPAN-CPT Side and Perspective ViewSPAN-CPT Top, Front and Bottom View SPAN-CPT Cable SPAN-CPT 60723108 KVH Development Terminated Cable Pin-OutFemale Male Pin Function Wire Pair Wire Color SPAN-CPT 60723107 KVH Standard Un-terminated Cable Pin-OutReplacement Parts Accessories and OptionsSPAN-CPT System Frequently Asked Questions Appendix COM-20000122 Rev March
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