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
GPS.G4-MS4-05043  Page 8

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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
GPS.G4-MS4-05043  Page 9

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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
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Schematic
 LeavetheRESET_Npinopenifnotused.Don’tdriveithigh!
 LeaveBOOT_INTpinopenifnotusedforfirmwareupdate.
 Planuseof2ndinterfaceforfirmwareupdatesorasaserviceconnector.
2.2 TIM-4R/LEA-4R Design
LEA-4R
TIM-4R
Odometer
Optional
Direction
Turn Rate Sensor
Filer, opto-couplers
Filer, opto-couplers
3Vlevels
3Vlevels
SPEED
FWD
SPIRATE
Low-Pass
filter
(MOSI)leaveopen
Digital
Temp
Sensor
A
D
GND
RF_IN
Coaxial
connector
RF_IN VANTV_ANT
AADET_N
VCC_REF
V_BAT
VCC(3V)
GND
GND
VDD18_OUT
TxD1/ TxD2
RxD1/ RxD2
USB
USB
TIMEPULSE
RESET_N
Optional
Optional
(BOOT_INT)leaveopen
Opencircuit
detection
(optional)
Gyro
Backup
Supply

Figure 5: Block Schematic of a complete LEA-4R / TIM-4R Design
2.2.1 Forward / Backward Indication
Useoftheforward/backwardindicationsignalFWDisoptionalbutstronglyrecommendedforgooddead
reckoningperformance.ConnecttoVDD18_OUT(1.8V)ifnotused.
Youneedtocheckthevoltagelevelsandthequalityofthevehiclesignals.Theymaybeofdifferentvoltage
levels,forexample12Vnominalwithacertaindegreeofvariation.UseofoptocouplersorotherapprovedEMI
protectionandfilteringisstronglyrecommended.
2.2.2 Odometer / Speedpulses
DRreceiversusesignalsfromsensorsinthecartoestablishthevelocityanddistancetraveled.Thesesensorsare
referredtoastheodometerandthesignalscanbedesignatedodometerpulses,speedpulses,speedticks,wheel
pulsesorwheelticks.Thesetermsareoftenusedinterchangeablywhichcansometimesleadtoconfusion.For
thesakeofconsistency,inthisdocumentwewillbereferringtothesesignalsasspeedpulses.
2.2.3 Power Supply for Gyroscope, Temperature Sensor and A/D Converter
TheGyroandtheA/D-Converterareespeciallysensitivetovoltagedropandripple.Thereforeacleanpower
supplymustbedesigned,whichis,forexample,notaffectedfromcurrentspikesproducedbytheGPSmodule.
LEA-4R/TIM-4R-SystemIntegrationManual/ReferenceDesign Design-In
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! Note ForbestDRperformanceit’srecommendedtodesignaseparate(reference)5Vpowersupplyforthe
gyroandtheA/Dconverter.
2.2.4 SPI Interface for Gyroscope and Temperature Sensor
TheLEA-4R/TIM-4RareconfiguredasSPImasters.FollowingsignalsareusedfortheSPIinterface:
Pin Signal name Direction Usage
22PCS2_NOutputSelectsA/Dconverterforgyrosignal
9PCS0_NOutputSelectstemperaturesensorwithSPIinterface
23SCKOutputSPIclock
2MISOInputSerialdata(MasterIn/SlaveOut)
1MOSIOutputSerialdata(MasterOut/SlaveIn),leaveopen
Table 1: SPI pin for LEA-4R
Pin Signal name Direction Usage
24PCS1_NOutputSelectsA/Dconverterforgyrosignal
25PCS0_NOutputSelectstemperaturesensorwithSPIinterface
26SCKOutputSPIclock
27MISOInputSerialdata(MasterIn/SlaveOut)
28MOSIOutputSerialdata(MasterOut/SlaveIn),leaveopen
Table 2: SPI Pin for TIM-4R
ThefollowingblockschematicspecifiestheA/DconverterandtemperaturesensorfortheLEA-4RandTIM-4R.
PleasenotethattheNationalLM70-3sensorfunctionsat3V.Ifthe5Vversion(LM70-5)isused,alevel
translationwithopen-drainbuffersandpull-upresistorsattheoutputsisrequired.
LEA-4R
TIM-4R
Turn Rate Sensor
(MOSI)
22K
10R
leaveopen
Gyro
SCK
MISO
PCS0_N
PCS1_N(TIM-4R)
+5V
REF
10uand
100 n
GND
GND
CONV
SCK
VCC
SC
CS
V
REF
IN
+
IN
-
12-Bit
A/DConverter
Linear LTC1860
Temperature
Sensor
National LM70-3
SDO
SI/O
V
+
GND
GND
GND
+3V
220n/100n
RATE
100n
GND
100K
VDD18
PCS2_N(LEA-4R)

Figure 6: Attaching A/D converter and temperature sensor using SPI interface
ForPCS0_N,apull-upresistorisnotrequiredsincethispinalreadyhasapull-upresistorinsideLEA-4R/TIM-4R.
LEA-4R/TIM-4R-SystemIntegrationManual/ReferenceDesign Design-In
GPS.G4-MS4-05043  Page 12

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Forbestresults,supplythe5Vvoltageforthegyroscopethroughalowpassfilterasillustrated.Providea
dedicatedreferencevoltagelinefromthegyroscopesupplypintotheVREFinputoftheA/Dconverter.
Addappropriatecouplingcapacitancesaccordingtotherecommendationsinthedatasheetsoftheillustrated
semiconductorproducts.Allshownresistorsshallhave5%accuracyorbetter.Allshowncapacitors(X7Rtypes)
shallhave10%accuracyorbetter.
! Note ForcorrectoperationwiththeLEA-4R/TIM-4Rfirmware,thiscircuitmustbeadoptedwithoutmaking
anymodificationssuchas,butnotlimitedto,usingdifferenttypesofsemiconductordevicesand
changingsignalassignment.
2.3 Pinout tables
LEA-4R TIM-4R
Pin
NameI/ODescriptionNameI/ODescription
1 MOSIOSPIMOSIVCCISupplyvoltage
2 MISOOSPIMISOGNDIGround
3 TxD1OSerialPort1BOOT_INTIBootmode
4 RxD1ISerialPort1RxD1ISerialPort1
5 VDDIOIPadvoltagesupplyTxD1OSerialPort1
6 VCCISupplyvoltageTxD2OSerialPort2
7 GNDIGroundRxD2ISerialPort2
8 VDD18OUTO1.8VoutputFWDIDirectionindication(1=Forward)
9 PCS0_NOSPIChipSelect0(Temperature
Sensor)
EXTINT1IExternalInterupt
10 RESET_NI/OResetVDD18_OUTO1.8Vsupplyoutput
11 V_BATIBackupvoltagesupplyGNDIGround
12 BOOT_INTIBootmodeGNDIGround
13 GNDIGroundGNDIGround
14 GNDIGroundGNDIGround
15 GNDIGroundGNDIGround
16 RF_INIGPSsignalinputGNDIGround
17 GNDIGroundRF_INIGPSsignalinput
18 VCC_RFOOutputVoltageRFsect. GNDIGround
19 V_ANTIAntennaBiasvoltageV_ANTIAntennaBiasvoltage
20 AADET_NIActiveAntennaDetectVCC_RFOOutputVoltageRFsection
21 FWDIDirectionIndication(1=Forward)V_BAT2IBackupvoltagesupply
22 PCS2_NOSPIChipSelect2(A/DConverter)RESET_NI/OReset(Activelow)
23 SCKOSPIClockSPEEDISpeedpulses
24 VDDUSBIUSBSupplyPCS1_NOSPIChipSelect1(A/DConverter)
25 USB_DMI/OUSBDataPCS0_NOSPIChipSelect0(TemperatureSensor)
26 USB_DPI/OUSBDataSCKOSPIclock
27 SPEEDISpeedpulsesMISOISPIMISO
28 TIMEPULSEOTimepulse(1PPS)MOSIOSPIMOSI
29 - TIMEPULSEOTimepulsesignal
30 - AADET_N3IActiveAntennaDetect
Shadedpinsrelatetodeadreckoningspecificfunctionality.
Table 4: Pinout LEA-4R/TIM-4R

2Batterybackupvoltageisnecessarytomemorizethelastvehiclepositionanddirectionoftheprevioustrip.Thisisparticularlyimportant
whentheprevioustripendedinanobstructedplace,forexampleaparkinggarage,andplausibledeadreckoningnavigationshallcontinue
whendrivingagain.

3AADET_Nwillonlybeoperatedasinputpinif“OpenCircuitDetection”foractiveantennasisactivatedorconfigured.
LEA-4R/TIM-4R-SystemIntegrationManual/ReferenceDesign Design-In
GPS.G4-MS4-05043  Page 13

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your position is our focus
2.4 Layout Design-In Checklist for ANTARIS®4
FollowthischecklistforyourLayoutdesigntogetanoptimalGPSperformance.
Layout optimizations
 IstheGPSmoduleplacedaccordingtotherecommendationinAntaris®4 System Integration Manual [5]?
 HaveyoufollowedtheGroundingconcept?
 Keepthemicrostripasshortaspossible.
 AddagroundplaneunderneaththeGPSmoduletoreduceinterference.
 Forimprovedshielding,addasmanyviasaspossiblearoundthemicrostrip,aroundtheserial
communicationlines,underneaththeGPSmoduleetc.
Calculation of the micro strip
 Themicrostripmustbe50OhmsanditmustberoutedinasectionofthePCBwhereminimalinterference
fromnoisesourcescanbeexpected.
 Incaseofamulti-layerPCB,usethethicknessofthedielectricbetweenthesignalandthe1stGNDlayer
(typicallythe2ndlayer)forthemicrostripcalculation.
 IfthedistancebetweenthemicrostripandtheadjacentGNDarea(onthesamelayer)doesnotexceed5
timesthetrackwidthofthemicrostrip,usethe“CoplanarWaveguide”modelinAppCadtocalculatethe
microstripandnotthe“microstrip”model.
2.5 Layout
PleaserefertotheAntaris®4 System Integration Manual [5] forlayoutrecommendations.

LEA-4R/TIM-4R-SystemIntegrationManual/ReferenceDesign Design-In
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your position is our focus
3 Receiver Description
3.1 Dead Reckoning enabled GPS module (DR module)
3.1.1 Architecture
ADeadReckoningenabledANTARIS®4GPSReceivercontainsanANTARIS®4GPSmodulewiththeadditionof
anEnhancedKalmanFilter(see Figure 7).ConnectedtotheDRmoduleareaturnratesensor(gyroscope)witha
temperaturesensor,odometer(speedpulsesignalsource)andadirectionindicator(forward–backward.).
SimilartotheANTARIS®4GPSmodules,theDRmodulesupportsactiveandpassiveantennasandhasan
optionalantennasupervisorcircuitry.Twoserialportsareavailableforcommunication(seeSection on Serial
Communication in Antaris®4 System Integration Manual [5])andarefreelyconfigurableforNMEAoru-blox
proprietaryprotocols.ItprovidesaTIMEPULSEsignalfortimingsynchronization(seeSection on Timing in
Antaris®4 System Integration Manual [5]).
InordertostoreanyDRspecificdatasuchaslastposition,currentheading,calibrationdata,thetemperature
compensationtable(TC)etc.,aDRmodulerequiresabackupbattery.Furthermore,thesedataarestoredin
Flashinrepetitiveintervals.
! Note Donotuseanypowersavingmodes(e.g.FixNow™Mode)astheDRalgorithmandpowersaving
modesareincompatible.
3.1.1.1 Enhanced Kalman Filter (EKF)
TheEnhancedKalmanFilteristhecoreoftheANTARIS®4DRTechnology.Itcombinesallthesensorsignals
(odometer,directionindicator,gyroscope,temperature),whicharesampledwith40Hzandcombinesthemwith
theGPSsolution.
TheGPSKalmanFilterandtheEnhancedKalmanFilteraretightlycoupledtoproducethebestpositionsolution
fromboth,theGPSsystemandthesensor-basedsystem.Theweightingbetweenbothsystemsiscontrolledby
GPSqualityindicators(e.g.DOPvalues,numberofSV,residualsetc.)andvariancesforallDRrelatedparameters.
LEA-4R/TIM-4R-SystemIntegrationManual/ReferenceDesign ReceiverDescription
GPS.G4-MS4-05043  Page 15

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GPS Front-End
Functionality
GPS Antenna
Gyro
Direction
A
D
Digital
Temp.
Sensor
Odometer
RF_IN
Position Calculation
KalmanFilter
Stage1
Dead Reckoning
Enhanced KalmanFilter
Weighted-Mixer
Stage2
1 Hz
update rate
40 Hz
update rate
1 Hz
update rate
DR enabled
GPS receiver
serialoutput
Calibration
Parameters,
Temperature
offsettable

Figure 7: Enhanced Kalman Filter
3.1.1.2 Sensor Integrity Check
TheSensorIntegrityCheckmonitorsthequalityoftheattachedsensors(gyroandodometer)andreports
unexpecteddrifts,ormalfunctions.AssoonastheDRsensorsaresufficientlycalibratedtheANTARIS®DR
Technologybeginswithsensorintegritychecks.
Ifasensorsignalisoutofrange,anerrormessageisproducedviaserialportandreportedinNAV-EKFSTATUS.
InthiscasetheEnhancedKalmanFilterisswitchedoffmeaningthatsubsequentlyonlyGPSpositionsolutions
arereported.
Torecoverthesystem,thesensorshavetobecheckedformechanicalfailures,allcalibrationparameter(Sensor
CalibrationandTemperatureCalibration)havetoberesetandaninitialcalibration(seeSection3.1.4)hastobe
done.
Forshortminimalerrorsthesystemisabletorecoveritself.InthiscasetheerrorwillbeclearedandtheDR
modulewillreportcombinedpositionsolutionsagain.
! Note TheINFmessage:“ERROR:EKFdisabled.Gyrodatainconsistent.”indicatesashutdownoftheDR
algorithmduetoinconsistencyofthegyrosignal.Ithappensifthegyroisdefectorthesystemis
miscalibrated.Torecover,checkthegyroandresetthereceiver.Ifithappensagain,resetallcalibration
dataandrepeataninitialcalibration.
! Note TheINFmessage:“ERROR:EKFdisabled.Tickdatainconsistent.”indicatesashutdownoftheDR
algorithmduetoinconsistencyofthespeedpulses/odometersignal.Ithappensifthespeedsignalline
orthesensorisbroken.Torecover,checktheodometersignalandresetthereceiver.Ifithappens
again,resetallcalibrationdataandrepeataninitialcalibration.
LEA-4R/TIM-4R-SystemIntegrationManual/ReferenceDesign ReceiverDescription
GPS.G4-MS4-05043  Page 16

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3.1.2 Input Signals/ Sensors
3.1.2.1 Turn rate sensor (Gyroscope)
Thegyroscopeindicatestheturnrateofthedevice.ThegyrooutputsignalisconnectedviaanA/Dconverterto
theDRmoduleandsampledat40Hz.Theintegrationofthegyrosignaloveronemeasurementperiodisequal
totherelativeturnofthedeviceduringthisperiod.
Therearethreemajorparametersofthegyroscope:
• Gyro Bias:Describestheoffsetofthegyrosignalataturnrateof0[deg/s].+/-25.0[deg/s]isthe
maximumallowedGyroBiasOffset.
• Gyro Scale Factor:Describestherelationofthetypicalgyrosensitivity[V/(deg/s)]oftherealmeasured
outputvoltage[V]totheactualturnrate[deg/sec].
Thisvaluehasanupperlimitof1.2,andalowerlimitof0.8.Thismeansthatthe
implementedgyrocanvaryby+/-20%,fromthetypicalgyrosensitivity.
• Gyro Bias as function of the temperature:
AnydifferencesfromtheGyroBiasOffsetovertheentiretemperaturerangearestoredin
alookuptable,calledTemperatureCompensationTable(TC).Thistablecoversa
temperaturerangeof–40degCelsiusto+80degCelsius.
TurnRate
w[deg/s]
+100
Gyro
Voltage
0-100
2.5
5.0
0
GyroBiasOffset
typicalGyroSensitivity
GyroScaleFactor
realGyroSensitivity

Figure 8: Gyroscope Signals
Gyro-
scope
A
D
DR
module

Figure 9: Gyroscope Signals Flow
! Note Themountingangleofthegyroinfluencesitsperformancesignificantly.Theangleofinclineshouldnot
exceedthemaximalvaluereferringtotheturnaxisofthevehicle.Consultthedatasheetofthegyro
carefullytochoosetheappropriatemountingtechniqueaswelltherightparametersettings(e.g.Gyro
Sensitivity,Polarity,maxangleofinclinationetc.)
Zaxis
Yaxis
Xaxis
zaxis
Angleofincline
Gyro
Gyro

Figure 10: Mounting of the gyroscope
LEA-4R/TIM-4R-SystemIntegrationManual/ReferenceDesign ReceiverDescription
GPS.G4-MS4-05043  Page 17

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your position is our focus

RefertotheLEA-4R/TIM-4Rdatasheetsforrecommendationsabouttheselectionofgyros.
! Note Pleasefollowdesignrecommendationsfromthegyroscopemanufacturersforproperanalogsignal
conditioning.
3.1.2.2 Temperature sensor
TheOutputoftheGyroscope(especiallyGyro Offset)isverysensitivetotemperaturechanges.Therefore
ANTARIS®DRmodulessupportanautomatictemperaturecompensationagainstthiseffect.
Toachievereasonableperformanceofthiscompensationthetemperaturesensorhastohaveamoderate
hysteresisandtheenvironmentaltemperatureshavetobereproduciblebyaround5degreesCelsius.
! Note ThetemperaturesensorhastobebuiltintheGyroscopeorasnearaspossibletotheGyroscopeto
measurethetemperatureofthegyroscope.
Temperature compensation
TocompensatethevariationoftheGyroOffsetwithdifferenttemperatures,theANTARIS®DRTechnology
maintainsaTemperature Compensation table(TC).Therangeisfrom–40to+85degreesCelsius.Thetableis
continuouslyupdatedwithnewvaluesassoonasthereceiverisstationary(noodometerpulsesattheinput)for
morethan3seconds.Thisprocessallowsthereceivertolearnaboutthetemperaturecharacteristicsofthe
individualgyroinitsspecificenvironment.
TheTCstabilizesasmoremeasurementsareobservedforthesametemperature.Fortemperaturerangesnot
measuredyettheTCBiasOffsetwillbeextrapolatedfromtheavailabledata.
degree
Celsius
+80
TCBias
Offset
+40
0
-40
0

Figure 11: TC compensation graph
! Note TheINFmessage:“WARNING:DiscardedTCMeasurement:RMSGyro=xx.xxxmV”indicatesthatthe
gyrohasatohighnoisetomeasureit’soffsetvaluesfortemperaturecompensation.Ifthismessage
appearsregularly,thegyromighthaveamechanicaldefectorismountedataplacewithtoohigh
vibrations.
3.1.2.3 Speedpulse Signal
ThespeedpulsesignalrequiredforDRmodulesmusthaveafrequencyrangefrom1Hzto5kHz(0Hzisequalto
aspeedof0km/hour).Thespeedpulsesignalmustbelineartothedrivenspeed.
LEA-4R/TIM-4R-SystemIntegrationManual/ReferenceDesign ReceiverDescription
GPS.G4-MS4-05043  Page 18

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TheScale Factor istheratiobetweenthefrequencyofthespeedpulsesignalandtherealspeed.Ithasa
maximumrangeof0.02[m/pulse]to1[m/pulse](i.e.from50kpulsesperkmto1000pulsesperkm.IftheScale
Factor exceedsthelowerorupperlimit,theoutputwillbeheldatthelimitingvalue.
1
x00.050
Measurement
Interval
x00.060 x00.070 x00.080 x00.090 x00.100 x00.110 x00.120
0 112211
SpeedpulsesperInterval
Timetag

Figure 12: Speed signal
! Note Non-linearityofthespeedpulsesignal(e.g.nopulsesbelow5km/h),mayleadtowrongdirection
calculationandthereforewrongpositioning.
! Note Ifthepulsefrequencyisbelowtheminimumfrequency(1Hz),speedwillbesetto0m/sandtheposition
outputisfrozenatthelastknownposition.
3.1.2.4 Direction (Forward/ Backward Signal)
Thedirectionsignalindicateswhetherthevehicleismovingforwardorbackward.Ifthesignalishigh,it
indicatesforwarddriving,butitcanbeconfiguredvice-versainUBX–CFG(Config)–EKF(EKFSettings).
It’srecommendedtouseadirectionindicatorforbestDRperformance.Ifnodirectionsignalisavailable,it’s
recommendedtosetthedirectiontoforward.
Consequencesifnodirectionsignalisavailable:
Direction
GPS coverage
Forward Backward
Insufficient to
determine a position
(DR only)
Thedirectionsignalindicatesthe
rightdirection
Good DR performance, all
position are valid
TheDRoutputwillindicateawrong
direction(alwaysforward).
DR positions are wrong as the
direction is wrong
Good GPS coverage Thedirectionsignalindicatesthe
rightdirection
 Good DR performance
Forshortdistancestheinfluenceofthe
mismatchingdirectionsignalcanbe
neglected(inorderofmeters,e.g.
maneuveringacarintoaparkinglot).
Forlongerdistancesitmighthave
significantimpacttothecalibration
parameter.
Table 5: Consequences of a missing direction signal
! Note Astheforward/backwarddirectionsignalisnotavailableinallcars,trytomakeuseofthereversegear
light.
LEA-4R/TIM-4R-SystemIntegrationManual/ReferenceDesign ReceiverDescription
GPS.G4-MS4-05043  Page 19

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your position is our focus
3.1.3 DR specific Parameters
3.1.3.1 DR specific GPS configuration
AstheGPSKalmanFilterandtheEnhancedKalmanFilterareoptimizedbyu-blox,donotchangethePower
ModeinUBX-CFG(Config)–RXM(ReceiverManager)oranyoftheUBX-CFG(Config)–NAV(Navigation)
parameters!
3.1.3.2 DR Configuration Options
ThefollowingconfigurationoptionsareavailablewiththeUBX–CFG(Config)-EKF(EKFSettings)message:
• TheEKFcanbeenabledordisabled.WhentheEKFisdisabledthemodulefunctionsonlyintheGPSmode,
thereisnoDRfunctionalityavailable.
• Itispossibletomanagedataandmemoryinthefollowingways.Pleasenotethatifthedefaultsettingsare
changedthemaximumnumberofflashwrite/releasecyclesneedstobetakenintoaccount:
• TheTemperatureTableandCalibrationDatacanbecleared.Whenthisisthecasethecalibrationbegins
again.
• TheintervaltosavethecontentofthetemperaturecompensationtablefromtheinternalBattery
BackupRAMtotheFlashmemorycanbedetermined.
• Thehardwareinterfacecanbeconfiguredinthefollowingways:
• TheDirectionPinPolaritycanbeset.Thedefaultis‘0–High=Forward’
• TheaxisorthedirectionofrotationoftheGyroifthevoltageoutputispositivecanbeset(default
settingis‘0–ClockwiseRotation).
• Thehardwarecanalsobeconfiguredtosimplifycalibration.Thisdoesnot,however,eliminatetheneedto
performacalibration.
• TheOdometercanbeconfiguredtosetthenumberofspeedpulsesperkilometer(defaultvalueis3500
[pulses/km]).
• ThenominalbiasvoltageandsensitivityoftheGyrocanbeset,aswellasthemaximumallowedRMSof
theGyro.ThisvalueisneededtocontrolthequalityofthemeasuredGyrooffsettobesavedinthe
temperaturecompensationtable.
TheDRStatusisreportedbythe(PUBX,05/EKFSTATUS)message.
! Note FordetailedinformationregardingtheconfigurationofthemessagespleaseseetheANTARIS 4GPS
TechnologyProtocolSpecifications[3].
®
3.1.3.3 DR Navigation Parameters (UBX – NAV (Navigation) – EKFSTATUS (Status))
Parameter Description Unit
Sensor Data 
SpeedPulsesNumberofspeedpulsesinonemeasurement
period[Pulses/Period]
PeriodDurationofonesensormeasurementperiod[ms]
MeanGyroUncorrectedMeanValueoftheGyrointhelast
period.
TemperatureMeasuredtemperatureatthegyroscope[°C]
DirectionSignalfromthedirectionindicator[forward/backward]

LEA-4R/TIM-4R-SystemIntegrationManual/ReferenceDesign ReceiverDescription
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