Ublox LEA-4R Quick setup guide

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your position is our focus
Abstract
mentscribestheatures dspecificationsofthe
LEA-4R/TIM-4RlowpowerDRGPSmodules.Itguidesthrougha
designandprovidesinformationtogetmaximumGPS
performanceatverylowpowerconsumption.
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u-blox AG
Zürcherstrasse68
8800Thalwil
Switzerland
www.u-blox.com
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Phone+4117227444
Fax+4117227447
[email protected]
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LEA-4R / TIM-4R
System Integration Manual / Reference Design
Manual
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This docu de fe an
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your position is our focus
Title LEA-4R/TIM-4R
Subtitle SystemIntegrationManual/ReferenceDesign
Doc Type Manual
Doc Id GPS.G4-MS4-05043
Revision
Index Date Name Status / Comments
InitialVersion TG
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Formostrecentdocuments,pleasevisitwww.u-blox.com
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Performancecharacteristicsshowninthisdocumentareestimatesonlyanddonotconstituteawarrantyorguaranteeofproductperformance.u-bloxdoesnot
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theyshallnotbeusedinsuchproducts.Indevicesorsystemswherebymalfunctionoftheseproductscanbeexpectedtoresultinpersonalinjuryandcasualties,
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makechangestothisproduct,includingitscircuitsandsoftware,inordertoimproveitsdesignand/orperformance,withoutpriornotice.
u-bloxmakesnowarranties,neitherexpressednorimplied,regardingtheinformationandspecificationscontainedinthisdocument.u-bloxassumesno
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module,Antaris,SuperSense,"yourpositionisourfocus",NavLox,u-center,AssistNow,AlmanacPlus,FixNowandEKFare(registered)trademarksofu-bloxAG.
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u-bloxAG.
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LEA-4R/TIM-4R-SystemIntegrationManual/ReferenceDesign 
GPS.G4-MS4-05043 

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your position is our focus
Preface
TheLEA-4R/TIM-4RSystemIntegrationManualprovidesthenecessaryinformationtosuccessfullydesigninand
configuretheseANTARIS®4-basedGPSreceivers.ThisdocumentspecificallyreferstotheDeadReckoning
technologyavailableintheLEA-4RandTIM-4R.ItdoesnotexplaintheANTARIS®4system.Fordetailed
informationregardingANTARIS®4technology,seetheANTARIS®4 System Integration Manual [5].
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Technical Support
Worldwide Web
Ourwebsite(www.u-blox.com)isarichpoolofinformation.Productinformation,technicaldocumentsand
helpfulFAQcanbeaccessed24haday.
By E-mail
Ifyouhavetechnicalproblemsorcannotfindtherequiredinformationintheprovideddocuments,contactthe
nearestoftheTechnicalSupportofficesbyemail.Useourservicepoolemailaddressesratherthananypersonal
emailaddressofourstaff.Thismakessurethatyourrequestisprocessedassoonaspossible.Youwillfindthe
contactdetailsattheendofthedocument.
By Phone
Ifanemailcontactisnottherightchoicetosolveyourproblemordoesnotclearlyansweryourquestions,call
thenearestTechnicalSupportofficeforassistance.Youwillfindthecontactdetailsattheendofthedocument.
Helpful Information when Contacting Technical Support
IfyoucontactTechnicalSupportpleasepreparethefollowinginformation:
• Receivertype(e.g.LEA-4R/TIM-4R)andfirmwareversion(e.g.V4.00)
• Receiverconfiguration,e.g.informofau-centerconfigurationfile.
• Cleardescriptionofyourquestionortheproblemtogetherwithu-centerlogfile.
• Ashortdescriptionofyourapplication
• Yourcompletecontactdetails
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LEA-4R/TIM-4R-SystemIntegrationManual/ReferenceDesign Content
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Contents
1Dead Reckoning Fundamentals...................................................................................7
1.1DeadReckoningenabledGPS(DR)..............................................................................7
1.2DeadReckoningPrinciple............................................................................................7
1.3DeadReckoningPerformance .....................................................................................8
2Design-In.....................................................................................................................10
2.1SchematicDesign-InChecklistforLEA-4R/TIM-4R .....................................................10
2.2TIM-4R/LEA-4RDesign ..............................................................................................11
2.2.1Forward/BackwardIndication............................................................................11
2.2.2Odometer/Speedpulses.....................................................................................11
2.2.3PowerSupplyforGyroscope,TemperatureSensorandA/DConverter.................11
2.2.4SPIInterfaceforGyroscopeandTemperatureSensor ..........................................12
2.3Pinouttables ............................................................................................................13
2.4LayoutDesign-InChecklistforANTARIS®4.................................................................14
2.5Layout ......................................................................................................................14
3Receiver Description...................................................................................................15
3.1DeadReckoningenabledGPSmodule(DRmodule)...................................................15
3.1.1Architecture .......................................................................................................15
3.1.2InputSignals/Sensors.........................................................................................17
3.1.3DRspecificParameters .......................................................................................20
3.1.4DRCalibration....................................................................................................21
3.1.5StorageofParameters ........................................................................................23
3.1.6StaticPosition.....................................................................................................24
3.2PowerSavingModes ................................................................................................24
3.3AntennaandAntennaSupervisor .............................................................................24
3.3.1OpenCircuitDetect............................................................................................24
4Navigation ..................................................................................................................25
4.1.1Overview............................................................................................................25
4.1.2NavigationUpdateRate......................................................................................25
4.1.3DynamicPlatformModel ....................................................................................26
4.1.4StaticHoldMode ...............................................................................................26
LEA-4R/TIM-4R-SystemIntegrationManual/ReferenceDesign Content
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4.1.5DegradedNavigation..........................................................................................26
4.1.6AlmanacNavigation ...........................................................................................26
4.1.7NavigationInputFilters.......................................................................................27
4.1.8NavigationOutputFilters....................................................................................28
4.1.9PositionQualityIndicators ..................................................................................28
4.1.10DGPS(DifferentialGPS) ......................................................................................31
4.1.11SBAS(SatelliteBasedAugmentationSystems).....................................................31
4.1.12RAIM(ReceiverAutonomousIntegrityMonitoring)..............................................31
5Product Testing...........................................................................................................32
5.1u-bloxIn-SeriesProductionTest ................................................................................32
5.2TestParametersforOEMManufacturer ....................................................................32
5.3SystemSensitivityTest ..............................................................................................33
5.3.1GuidelinesforSensitivityTests ............................................................................33
5.3.2‘Go/Nogo’testsforintegrateddevices ...............................................................33
5.4TestingofLEA-4R/TIM-4RDesigns ............................................................................34
5.4.1DirectionSignal ..................................................................................................34
5.4.2SpeedpulseSignal ..............................................................................................34
5.4.3Gyroscope(Rate)Input .......................................................................................34
5.4.4TemperatureSensor ...........................................................................................34
5.4.5EraseCalibration ................................................................................................34
6PC Support Tools ........................................................................................................35
AMigration from TIM-LR to TIM-4R .............................................................................36
A.1MigrationfromTIM-LRtoTIM-4Rpinout .................................................................37
BDefault Settings..........................................................................................................38
B.1Hardware .................................................................................................................38
B.2Navigation................................................................................................................38
B.3PowerSavingModes ................................................................................................39
B.4CommunicationsInterface ........................................................................................40
B.5Messages(UBX–CFG–MSG) ..................................................................................40
B.6Messages(UBX–CFG–INF) .....................................................................................41
B.7TimingSettings.........................................................................................................42
LEA-4R/TIM-4R-SystemIntegrationManual/ReferenceDesign Content
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CReference Design for TIM-4R.....................................................................................42
DMechanical Data.........................................................................................................43
D.1Dimensions...............................................................................................................43
D.2Specification.............................................................................................................44
Glossary ............................................................................................................................45
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LEA-4R/TIM-4R-SystemIntegrationManual/ReferenceDesign Content
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1 Dead Reckoning Fundamentals
1.1 Dead Reckoning enabled GPS (DR)
DeadReckoningisafeaturetomakeGPSmoreaccurateandreliableinurbancanyonenvironmentsandduring
GPSoutages.Itusesadditionalsensorstomeasurespeed,headinganddirection(forward/backward).Therefore
aDRenabledGPSreceiverconsistsofaGPSreceiver,aturnratesensor(gyroscope)andaspeedindicator
(odometer1).BycombiningtheinformationofallsensorsapositioncanbedeterminedevenifGPSpositioningis
degradedorimpossibleduetorestrictedskyview.ThismeansthataDRenabledreceivercontinuestoreport
positionswhenGPSsignalsareblocked,suchasintunnelsorinheavyurbancanyonenvironments.
GPS Kalman Filter
GPS
receiver
Dead Reckoning
Parameter Enhanced Kalman Filter (EKF)
Position,
Speed,
Direction,
Time
Calibration
TurnRate
Speed
Forward/Backward
GPS
Signals
GPSPosition,
GPSData
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Figure 1: Dead Reckoning Block diagram
1.2 Dead Reckoning Principle
IncontrasttoGPS,whichdeliversabsolutepositions,DeadReckoningisarelativemethod.Thesensorsgive
informationforadefinedmeasurementperiod,andthelocationiscalculatedrelativetothepreviouslyknown
position.ThereforeanabsoluteGPSpositionisrequiredasastartingpoint,whichisthelastknownGPSposition.
δ
s
y
n
x
n
y
n+1
=y
n
+dy
x
n+1
=x
n
+dx
Known parameters:
s
=Traveleddistance(odometer,direction)
δ =Newangle(gyroscope)
dy =scos( δ )
dx =ssin( δ )
=last GPSposition
=DRposition
x
y

Figure 2: Dead Reckoning Principle
Parametersusedfortherelativepositioncalculationare:

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1Anodometerisbydefinitionadevice,whichmeasureslineardistancetraveled.GPSreceiverscanalsoincludesoftware(alsoknownasan
odometer)usedtocalculatethisdistance.
LEA-4R/TIM-4R-SystemIntegrationManual/ReferenceDesign DeadReckoningFundamentals
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• Distance travelled:Odometerpulses
• Direction:Forward/backwardindicator
• Angular turn rate:Gyroscope
1.3 Dead Reckoning Performance
AsDRisanincrementalalgorithm,thequalityoftheDRpositiondependsverymuchonthequalityandstability
ofthesensorsused.Anaccuratemodel,lowtolerancesandlowthermaldriftsareessentialforreliableposition
output.
TheperformancefiguresofaDRsystemarealwaysproportionaltodistancetraveledortime.
y
n
x
n
calculated route
based on sensor
signals
Known parameters:
S
=Traveleddistancesince GPSSignalslost
d =Distanceerror
Performance parameters:
d/S
=Positionerrorpercentageincomparison
todistancetraveled
∆Φ = Angularheadingerror
Fix types:
=GPSposition
=DRposition
=Realposition
d
∆Φ
Actual route
Length = S
x
y

Figure 3: Dead Reckoning Performance Parameters
TheseamlesstransitionbetweenabsoluteGPSpositionsandrelativeDRpositionsisadvantageousingetting
optimalperformancefromaDRenabledGPSreceiver.ANTARIS®4GPSTechnologyemploysblendedalgorithms
toobtaintheoptimumfrombothsystems.
GPSPositioningisweightedmoreheavilyaslongastheGPSparameter(e.g.DOP,numberofsatellites,signal
quality)indicatesgoodandreliableperformance.Insituations,wheretheGPSsignalsarepoor,reflectedfrom
buildings(multipath)orjammedtheDRsolutionisusedwithahigherweighting.
Poor GPSNo GPS Good GPS
GPS DRGPS DRGPS DR
Extrapolation Blending Calibration
EKF EKF EKF
Position,Velocity,Time
Position,Velocity,Time
Position,Velocity,Timefrom
real-timeclock
Altitudeheldconstant

Figure 4: Dead Reckoning Blending
LEA-4R/TIM-4R-SystemIntegrationManual/ReferenceDesign DeadReckoningFundamentals
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your position is our focus
• No GPS:DuringGPSloss,onlyDR-(sensorbased)positionsarereported.Thepositioniscalculated
basedonthesignalsoftheturnratesensorandspeedsensor,withreferencetothelast
knownGPSsolution.
• Poor GPS:InurbancanyonswithfastchangingskyvisibilityorduringdegradedGPSreception,the
ANTARIS®4DRTechnologyperformsacalculationbyblendingtheGPSandsensorbased
positioning.
• Good GPS:WithgoodGPSperformanceandoptimalskyview,theGPSpositionhasahigherweight
thantheDR/sensorbasedpositionontheoverallnavigationsolution.Inthissituation,the
GPSpositionvaluesareusedtocalibratetheDRsensorsortoperformsensorintegrity
checks(toestablishifthesensorsarewellcalibrated).
LEA-4R/TIM-4R-SystemIntegrationManual/ReferenceDesign DeadReckoningFundamentals
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your position is our focus
2 Design-In
ThissectionprovidesaDesign-InChecklistaswellasReferenceSchematicsfornewdesignswithLEA-4R/TIM-4R.
FormigrationofexistingTIM-LRproductdesignstoTIM-4RpleaserefertoAppendix A.
2.1 Schematic Design-In Checklist for LEA-4R/TIM-4R
Designing-inaLEA-4R/TIM-4RGPSreceiveriseasy,especiallywhenadesignisbasedonthereferencedesignin
Appendix C.Nonetheless,itpaystodoaquicksanitycheckofthedesign.Thissectionliststhemostimportant
itemsforasimpledesigncheck.TheLayoutChecklistinSection 2.4alsohelpstoavoidanunnecessaryrespinof
thePCBandhelpstoachievethebestpossibleperformance.
! Note It’shighlyrecommendedtofollowtheDesign-InChecklistwhendevelopinganyANTARIS®4GPS
applications.Thiscanshortenthetimetomarketandsignificantlyreducethedevelopmentcost.
! Note Forimportantinformationexplainingthevariousaspectsofthischecklistseesection3intheAntaris®4
System Integration Manual [5]
Check Power Supply Requirements and Schematic:
 Isthepowersupplywithinthespecifiedrange?
 PlaceanyLDOasnearaspossibletotheVCCpinofthemodule;ifthisisnotpossibledesignawidepower
trackorevenapowerplanetoavoidresistancebetweentheLDO/powersourceandtheGPSModule.
 IstherippleonVCC below50mVpp?
Backup Battery
 AbackupbatteryisamustforDRenabledGPSreceiver’sdesigns.
 MakesuretoconnectabackupbatterytoV_BAT.LEA-4R/TIM-4Rdonotoperatewithoutabackupbattery.
 Whenyouconnectthebackupbatteryforthefirsttime,makesureVCC isonor–ifnotpossible–powerup
themoduleforashorttime(e.g.1s)ASAPinordertoavoidexcessivebatterydrain.
 Whilepoweroff,makesuretherearenopull-upordownresistorsconnectedtotheRxD1,RxD2,EXTINT0
andEXTINT1asthiscouldcausesignificantbackuporsleepcurrent(>25µAormoreinsteadof5µA).
Antenna
 Activeantennaissupported.
 Thetotalnoisefigureshouldbewellbelow3dB.
 Ifapatchantennaisthepreferredantenna,chooseapatchofatleast18x18mm(25x25mmisevenbetter).
 Makesuretheantennaisnotplacedclosetonoisypartsofthecircuitry.(e.g.micro-controller,display,etc.)
 Foractiveantennasadda10RresistorinfrontofV_ANTinputforshortcircuitprotectionorusethe
antennasupervisorcircuitry.
 WhenmigratingfromTIM-LRreduceR5oftheAntennaShortandOpenSupervisorcircuitto18k.
 Adaptthevalueofsomeoftheresistorsinthereferencedesigntothe3.0Vvoltagelevels(seeAppendix C).
Serial Communication
 ChooseUBXforanefficient(binary)datahandlingorifmoredataisrequiredthansupportedbyNMEA.
 WhenusingUBXprotocol,checkiftheUBXqualityflags(seeSection 4.1.9.2)areusedproperly.
 CustomizetheNMEAoutputifrequired(e.g.NMEAversion2.3or2.1,numberofdigits,outputfiltersetc.)
LEA-4R/TIM-4R-SystemIntegrationManual/ReferenceDesign Design-In
GPS.G4-MS4-05043  Page 10