Instruction Manual

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NAV540UserManual

7430‐0808‐01Rev.B

Page19

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temperatureandnon‐linearityeffectsduringCrossbow’smanufacturingandtestprocessusingautomated

thermalchambersandratetables.

• Coupledtothe6‐DOFMEMSinertialsensorclusterisahighperformanceDigitalSignalProcessor(DSP)that

utilizestheinertialsensormeasurementstoaccuratelycomputenavigationinformationincludingattitude,

heading,andlinearvelocitythrudynamicmaneuvers(actualmeasurementsareafunctionoftheGNAV540

asshowninTable2).

TheDSPprocessormakesuseofinternalandexternalmagneticsensorand/orGPSdatatoaidthe

performanceoftheinertialalgorithmsandhelpcorrectlongtermdriftandestimateerrorsfromtheinertial

sensorsandcomputations.Thenavigationalgorithmutilizesamulti‐stateconfigurableExtendedKalman

Filter(EKF)tocorrectfordrifterrorsandestimatesensorbiasvalues.Thisalgorithmrunsona150MHz

32‐bitDSPthathasapproximatelyfourtimesthecomputationalpowerofCrossbow’searliergeneration

InertialSystems.

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AsignificantfeatureoftheGNAV540istheextensivefieldconfigurability.

ThisfieldconfigurabilityallowstheGNAV540InertialSystemstosatisfyawiderangeofapplicationsand

performancerequirementswithasinglemassproducedhardwareplatform.Thebasicconfigurability

includesparameterssuchasbaudrate,packettype,andupdaterate,andtheadvancedconfigurability

includesthedefiningofcustomaxesandhowthesensorfeedbackisutilizedintheKalmanfilterduringthe

navigationprocess.

TheGNAV540unitispackagedinafullysealed,lightweighthousingthatprovidesEMI,vibrationandmoisture

resistancetolevelsconsistentwithmostland,marine,andairborneenvironments.TheGNAV540utilizesanRS‐422

seriallinkorEthernetinterfacefordatacommunication,andeachdatatransmissionincludesaBIT(Built‐In‐Test)

messageprovidingsystemhealthstatus.TheGNAV540issupportedbyCrossbow’sNAV‐VIEW2.2,apowerfulPC‐

asedoperatingtoolthatprovidescompletefieldconfiguration,diagnostics,chartingsensorperformance,anddata

oggingwithplayback.

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