LemonRx7-ChannelIntegratedTelemetryReceiver 1

InstructionsLemonRxDSMX-Compatible7-ChannelFull-Range

IntegratedTelemetryReceiverFullRangewithDiversityAntennaandPPM

TheLemonRx7-ChannelIntegratedTelemetryReceivercombinesinasinglecompactpackagethefunctionsofahighperformanceDSMX-compatibleradiocontrolreceiverandafull-rangetelemetryunitthatsupportsSpektrumtelemetry-enabledtransmitters.

Contents PART1.Overview........................................................................................................................................1

PART2.UsingtheLemonReceiver/TelemetryUnit....................................................................................5

A.BasicRequirementsandSetup............................................................................................................5

B.Binding.................................................................................................................................................6

C.Failsafe.................................................................................................................................................7

D.Telemetry............................................................................................................................................8

E.ConnectingServosorFlightController................................................................................................8

PART3.AdditionalInformationforAdvancedUsers...................................................................................9

A.PPMmode...........................................................................................................................................9

B.RSSI......................................................................................................................................................9

C.AntennasandSatellites.....................................................................................................................10

D.PowerConsiderations.......................................................................................................................11

E:VoltageRecalibration.........................................................................................................................11

F:CalibratingtheOptionalV/ISensor...................................................................................................13

G.CreatingandReadingTelemetryLogFiles........................................................................................15

H.ServoOutputTiming.........................................................................................................................18

PART 1. Overview • BoththeradiocontrolreceiverandthetelemetrytransmissionfunctionsoftheLemonunitare

classifiedasfullrange.Thisisachievedusingdualantennasanddiversityswitchingtoensuremaximumsignalreliabilityinbothdirections.Note,however,thatwhilethereceiverhascontrolsignalrangewellbeyondthenormallimitsofvisibility,thelowerpowerofthereturntelemetrysignalmeansthatthetelemetrydisplaymayoccasionallyfreezewhilethemodelisstillunderfullcontrol.

LemonRx7-ChannelIntegratedTelemetryReceiver 2

• Thelownoiseamplifier(LNA)inthereceiverensuresmaximumsensitivitytodetectweakradiofrequency(RF)signals.UsersshouldexperienceanoticeableimprovementinrangecomparedtothepreviousgenerationofLemonRxreceiversandtootherbrandsofDSM2andDSMXreceiversandcompatibles.Independenttestinghasshownthisreceivertohavesignificantlymorerangeinastandardreducedpowerrangetestthanseveralothercomparablereceiversthatweretestedunderidenticalconditions.

• Theunithasantennasoftheextendedtypeforversatileplacementinmanytypesofapplication.Theactivereceiving/transmittingelementisthelast32mmoftheantennacable,whichhassemi-transparentwhitePVCshield.

• Inaddition,aDSMXsatellitereceivercanbeattachedtoenhancesignalsecurity.SatelliteswithandwithoutdiversityantennasareavailablefromLemonRx.

• Telemetryfromtheunitcanbothbedisplayedon-screenandspokenbycurrentSpektrumtelemetry-enabledtransmitters:DX6G2,DX7G2,DX9(includesBlack),DX10t,DX18,DX18QQ,DX18G2(includesStealth),andDX18t.TheolderDX8,andtheoriginalDX18,candisplaydataon-screen,butlackvoicecapabilityandthereforecannotspeakalarms.1

• Built-insensorsprovidereceivervoltage,internaltemperatureandRSSI(signalstrength).Theincludedexternalsensorsaddflightpackbatteryvoltage(whenconnectedtothepositiveconnectionoftheflightbattery)andamoreaccurateexternaltemperatureprobethatautomaticallyreplacestheinternalvalue.

• Anoptionalvoltage/current(V/I)sensorisavailablethatmeasuresupto30Vand60A(seetheLemonRxwebsiteunderAccessories).

• AtrueRSSI(ReceivedSignalStrengthIndicator)presentsvaluesonascaleof100to0assignaldeclines;thevalueisdisplayedasparameter"A"onthetransmitter’sFlightLogpage.

• RSSIOutforsupportofanon-screendisplay(OSD)isalsoavailablefromthereceiver(usingthesuppliedlead)intheformofananalogvoltagerangingfrom3V(=100%)to0V.

• Theunitrequiresapowersupplyof4.5Vto7.4V.Itisimportanttonotetheminimumvoltage,whichishigherthanrequiredbymostLemonreceivers.Inparticular,thisreceivercannotbeoperatedfromasingleLiPocell.

• ThepinslabeledBind/AUX2dodoubledutyasbindpinsaswellasChannel7(AUX2);whenabindplugispresentthereceivershutsdownservooutput.EithertheservocanbeconnectedafterbindingoritcanbeattachedtoonebranchofaY-cable,withthebindpluginsertedintotheotherbranchandthenremovedafterbinding.

• Noseparatestand-alonetelemetryunitisrequiredwiththisreceiver.Norcansuchaunit,Lemonorother,beconnected,astheseconddatastreamwouldinterferewiththatoftheintegratedunit.

• UserPresetFailsafeonallchannelscanbesetbythepressofasinglebuttononthereceiver.Iffailsafeisnotset,theunitdefaultstoemittingnopulsesonlossofsignal.

1UnliketheLemonstand-alonetelemetryunit,thisreceiverdoesnotworkwiththenowobsoleteSpektrumTR1000STiTelemetryInterfaceforiPadandiPhone.

LemonRx7-ChannelIntegratedTelemetryReceiver 3

• ThereceivercanbesettooutputeitherindividualPWMsignalsforeachchanneloracombinedPPM(cPPM)signal(ineitherFutaba/HitecorJR/Spektrumchannelorder)carryinginformationforallchannelsonasinglewire.

• LEDlightsindicatethereceiverstatusasfollows:

o RED:SOLID–successfulbindRFlinktotransmitter;FLASHINGRAPIDLY–bindmode;

o GREEN:OFF–nopulseonsignalloss;SOLID–presetfailsafe;

o BLUE:OFF–PWMservomode;FLASHING–PPM-Fmode;SOLID–PPM-Jmode;

Figure1.1Whatyougetinthepackage.

Thepackvoltage/currentsensorshownontheleftisnotincludedwiththereceiverasstandard.ItisanadditionalaccessoryandisthesameasusedwiththeLemonstand-alonetelemetryunit.

LemonRx7-ChannelIntegratedTelemetryReceiver 4

Figure1.2TheLemon7-channelReceiver/TelemetryUnitremovedfromitscase.

Thisshowswhatthereceiverlookslikewithoutitscaseandidentifiesthevariousconnections.ThethreewhiteconnectorsfortheSatelliteandthetwotelemetryleadsareidenticalandnotallorientedthesameway.Norarethewiresallcolor-coded.Takespecialcaretofollowthelabelsonthecasewhenpluggingthemin,particularlythevoltagesensewire.Connectingthepackvoltagetothewrongpinwillalmostcertainlycausedamage.

LemonRx7-ChannelIntegratedTelemetryReceiver 5

PART 2. Using the Lemon Receiver/Telemetry Unit

A. Basic Requirements and Setup

Transmitter Toprovidebothradiocontrolandtelemetry,thisreceiverrequiresaSpektrumDSMXtelemetry-enabledtransmitter(seecurrentlistofcompatibletransmittersonpage2).

Itwillfunctionasareceiveronly(notelemetry)withawiderangeofotherSpektrumtransmittersandmodules,includingolderDSM2units,aswellaswithvariouscompatibletransmittersandmodules.

Thereceiveroperatesonlyat22mSframerateandwilloutput22mSframesevenifthetransmitterframeratehasbeenforcedinto11mSmode.

WithaDSM2transmitter,oraDSMXtransmitterinDSM2mode,thereceiverwillautomaticallyswitchtoDSM2whenitdetectsthebindsignal.

Instal lation Thereceivershouldbeinstalledusingnormalgoodpracticesfor2.4GHzequipment.Particularattentionshouldbepaidtothelocationandorientationoftheactiveportionofthedualantennas(thelast32mmofthecable,fromwhichtheoutersheathhasbeenremovedtoexposethewhiteinnercable).Thetwoantennasshouldberoutedsoastoachievewideseparationwiththeactiveportionsatrightanglestoeachother.

Theactiveportionsoftheantennasshouldbereasonablystraightforoptimumreceivingandtransmittingperformance,buttherestofthecablecanbecurvedgentlyasrequired.Thecoaxialcableusedforantennasisfragileandmustnotbekinkedorallowedtofloparoundorvibrateexcessively.

Theactiveportionsoftheantennasshouldnotbeimmediatelyadjacenttoconductiveitemssuchaswiring,ESC,batteryorcarbonfiberthatcouldblockthesignal(notethatnon-conductivematerialslikemostfoam,balsa,ply,etc.posenoproblem2).Theantennasshouldbelocatedsothatregardlessoftheattitudeoftheaircraft,atleastoneofthemhasaclearlineofsighttothetransmitter.Forexample,itisimportanttoavoidlocatingtheactiveportionsoftheantennaswherebothcanbeblockedsimultaneouslybythebatteryfromreceivingagoodsignal.SeeSection3C,page10forfurtherdetails.

Itisimportanttoconductarigorousreducedpowerrangetestbeforethefirstflight.Themodelshouldbeplacedonawoodentableorsimilarnon-conductivesupport.PutthetransmitterintoRangeTestmode(seetransmittermanual).Withthereceiverturnedon,walkawayabout25m(30paces)andthencirclethemodelwhiletestingcontrol.Ifthereareanyanglesatwhichcontrolisreducedorlost,gobackandreviewtheinstallation.

Iftelemetryisfunctional,theRSSIvalueshouldbemonitoredduringtherangetest;thiswillhelptoidentifyanyproblemswiththeinstallation(seesection3B,page9,foradditionalinformationonRSSI).

Atthebeginningofeachsubsequentflyingsession,doabriefreducedpowertestat25mtocheckthatallisworkingproperly.Thereisnoneedtorepeatthecirclingofthemodel.

2Somefoamplasticandheatshrinktubingisconductiveandcaninterferewithreception.Totestamaterial,zapitinamicrowaveovenforafewseconds.Ifitwarmsup,itshouldnotbeusednearthereceiverorantennas.

LemonRx7-ChannelIntegratedTelemetryReceiver 6

Power Requirements ThisreceiverrequiresahighervoltagepowersupplythanmostotherLemonreceivers,althoughitwillrecoverwellfrombrieflowvoltagebrownouts.EnsurethatunderloadyourBECorreceiverbatterydoesnotfallbelowthe4.5Vminimumatanytime.

Beawarethatsomecheap“3A”BECs,includingthoseinESCs,areoptimisticallyratedandcaneasilybeoverloadedbymultipleservosandotherhighdraindevicessuchasarefoundinsomemodernparkfliersize“ReadytoFly”aircraftequippedwithretracts,flaps,lights,soundsystems,etc.Some4.8VNiMHreceiverpacksalsohavelimitedcurrentcapabilityandmaydropvoltagesignificantlyunderload;besuretousecellsthatcandeliveradequatecurrentfortheloadplacedonthem.

B. Binding Bindingrequiresthatthereceiverbeputintobindmodefirstandthatthetransmitterthenbepoweredupinitsbindmode(seeyourtransmittermanualforspecificinstructions).

Procedure 1. Insertthebindplugintothefirstsetofpins(labeledBind/AUX2)withnopowerconnected

(Figure2.1).Ifasatelliteistobeuseditmustbeconnectedwhilebinding.

Figure2.1–Bindpluginsertedwithpowerdisconnected.

2. ProvidepowerviaESC,BECorseparatereceiverpack(heretheESCisconnectedtochannel1).Oncethebatteryisconnected,arapidlyflashingREDLEDbeneaththereceiver(andonthesatelliteifused)indicatesbindmode.Donotproceedtostep3unlessthelightisflashingcorrectly.

Figure2.2–Solidredlightonbottomofreceiverindicatessuccessfulbinding.

3. Turnonthetransmitterinbindmodeapproximately2metersawayfromreceiver.ThereceiverLEDshouldchangetoslowlyflashing,thentosteadyREDindicatingsuccessfulbind(seeFigure2.2).Ifyoudon’tgetasolidredlightonthereceiver(andsatelliteifused),seetheadvicebelow.

LemonRx7-ChannelIntegratedTelemetryReceiver 7

4. Fornormaloperationofthereceiver,removethepowerandbindplugatthispoint;ORTosetFailsafe(Section2C)orPPMmode(Section3A),leavepowerconnectedandbindpluginplace.

Binding Problems ItisnotunusualtoencounterdifficultiesbindingDSM-typereceivers,withthereceivereithercontinuingtoflashrapidlyorstartingthebindprocessbutneverattainingthesolidlightthatindicatesalink.BeingverysensitivetheLemonRXTelemetryReceivermaybealittlefussierthanusualaboutbindconditions.

Bindproblemscanusuallybeovercomebysimplyincreasingthedistancebetweentransmitterandreceiverduringbind.Eventhen,morethanonetrymaybeneededtoachievesuccess.Foreachtry,repeattheentiresequence,startingwithbothreceiverandtransmitterpowereddown.

Ifbindingfailsat2meters,startagain,movingfurtherawaybeforeturningonthetransmitterinbindmode,andhaveyourbodybetweenthetransmitterandreceivertoattenuatethesignalfurther.Whenbinding,stayawayfrommetallicobjects(suchascars,wirefencesandsteeltables),aswellasdampgroundandotherconductivesurfaces.WirelessroutersandotherWiFisourcescanalsoinhibitbinding.

C. Fai lsafe Failsafewillbeactivatedwheneverthereceiverisunabletoreceiveasignalfromitsboundtransmitterforaboutonesecond.Onceavalidsignalisagainreceivedthereceiverwillresumetransmittercontrol.

ThedefaultfailsafeactionifPresetFailsafeisnotusedisforthereceivertocutoffpulsesonallchannels.Thiswillcausemostmodernspeedcontrols(ESCs)toshutdownthemotorandwillleaveservoswherevertheyhappentobeatthemoment.Inthismode,thegreenlightisOFF.

WARNING:DefaultfailsafeisunsatisfactoryforIC(fuel)poweredmodels,astheenginewillcontinuetorunatthepowersetbythethrottleservowhenthesignalwaslost.

TheoptionalUserPresetFailsafe,indicatedbygreenlightON,providesspecificoutputsoneachofthesevenchannelsintheeventofsignalloss.PresetFailsafeisactivatedasfollows:

1. Forelectricmodels,removethepropeller(s)orotherwiseensurethatthemodelissafe.

2. Followthebindstepsfrom1to3.DONOTremovethebindplugorpoweratthispoint.

3. Adjustthetransmittersticks,switches,etc.forallchannelstothedesiredfailsafeoutputs.Formostpoweredmodelsthecriticalfailsafeactionistoensurethatthrottlegoestozero.

4. PresstheFailsafe/Modebuttonbriefly(lessthan1second).AGREENlightindicatesthatfailsafepositionshavebeenmemorizedandPresetFailsafeisenabled.Pressingthebuttonagainbrieflywilldisablepresetfailsafeandcausethegreenlighttoturnoff.

5. Testfailsafebyturningoffthetransmitterandverifyingthatallcontrolsgotothedesiredpositions.Usecare,asanerrorinsettingfailsafecouldcausethemotortostart,retractgeartoactivate,etc.Turnthetransmitterbackon,butnotethatthereceiverwillnotrecoverfromfailsafeuntilthetransmitterisagainfullyoperational,whichmaytakesometime(sodon’tdothistestintheair!).

Note:HoldingthebuttonformorethanaboutasecondwillactivatePPMmode,asindicatedbyablueLED(seeSection3A,page9).UnlessPPMmodeisrequired,longpressthebuttonagainandrepeatuntiltheblueLEDisOFF.Thenrepeatsteps3and4ofthepresetfailsafeprocedure.

Normally,failsafestatusandchannelsettingsareretainedbythereceiveruntildeliberatelyreset.HoweveritispossibletochangethesettingunintentionallyifanerrorismadewhilecalibratingthereceiverorsettingPPMmode.Alwayscheckthefailsafesettingaftersuchoperations.

LemonRx7-ChannelIntegratedTelemetryReceiver 8

D. Telemetry ThereceiverwillautomaticallytransmittelemetrytoaSpektrumtransmitterwithtelemetrycapability.Tomonitorthevariousparameters,thetransmitter’stelemetryoptionmustbeenabled:

o Receivervoltage.Automatic,noexternalsensororleadrequired.

o RSSI–signalstrength.Automatic.Displayedontransmitterunderparameter“A”.

o Temperature.Automatictransmissionofinternaltemperature.Formaximumaccuracy,however,theprovidedexternaltemperaturesensorshouldbeconnected.

o Batteryvoltage.Requiresaconnectiontothebatterypositiveusingthevoltagesensingwireprovided.Assuppliedthisisalreadycalibrated.ForrecalibrationofBatteryvoltage,seesection3E,page11.ThebatteryvoltagewireisnotneededifaV/Isensorisused.

HINT:AsimplewaytomonitorflightpackvoltagewithoutmodifyingthehighcurrentpowerwiringistoattachthevoltagemeasuringwiretothemostpositivepinoftheLiPobalanceconnector.

o Batterycurrent.RequirestheoptionalV/Isensorconnectedinthemainpowerlead.Thissensormustbepurchasedseparately.TheV/Isensorplugsinplaceofthesimplevoltagesensingwireandprovidesbothcurrentandvoltageinformation.

o RSSIout–RSSIisautomaticallydisplayedonthetransmitterscreen,butforusewithanOSD(OnScreenDisplay)usedwithanFPV(FirstPersonView)setuptheRSSIvalueisavailableonthesparewireoftheexternaltemperaturesensorcable.TheanalogvoltageoutputvariesinproportiontoRSSIfrom3.0Vdownto0Vasthesignaldiminishes.

WARNING:Donotplugthevoltagesensorcableintothetemperaturesensorsocket!Ifabatteryisattachedthisisalmostcertaintodamagethereceiver.

EnablingtelemetryinvolvesselectingeachfieldyouwanttodisplayintheTelemetrysetupscreenontheSpektrumtransmitter.ThefieldsavailableonthetransmitterscreenvaryalittledependingonwhichversionofAirwarethetransmitterisrunning.Volts,Amps,TempandRxV(plusRSSI,whichwillautomaticallyappearinthe“A”field)aretheonlyparametersthatcanbedisplayedusingthisreceiver.NotethatthePowerboxfieldsarenotactiveandthisreceiverthereforedoesnotdisplaymAhconsumed.

OntheSpektrumTelemetrysetupscreenthereisalistofnumberedfields.Thenameofthefieldindicatesthetelemetryparametertobedisplayedinthatfield(orindicatesitisEmpty).Usethescrollwheeltomovebetweenthefieldsandclicktoselectone.Youcanthenchoosewhatisdisplayed.ForthisreceivertherelevantchoicesareVolts,Amps,TempandRxV.Clickingafterselectingthedisplaywhiletheframeisstillflashingwilltakeyoutoasecondscreenwherevariousparameterscanbeset.ForexamplewithVoltsyoucanchoosewhetherthedisplayisActive,whetheraMinimumand/orMaximumvoltagealarmissetandwhattypeofalarmitis.TheoptionsavailablemaydependontheversionofAirwareyourtransmitterisrunning.

E. Connecting Servos or Fl ight Control ler ThereceiverisshippedinServoModewiththesignalforeachchannelavailableatthecorrespondingpin,asmarkedonthecase.Thisallowsservostobepluggeddirectlyintothereceiverintheusualway.

Tosupportanumberofthirdpartyflightcontrollers,thereceivercanbesettooutputaCombinedPPMsignal(cPPM),alsoknownasjustPPM,thatcarriesallchannelsonasinglewireconnectedtotheAUX1/PPMpins.SeeSection3A,belowfordetailsonsettingPPMMode.

PPMModeisindicatedbyaBLUElight,eitherflashingorsolid.ServoModehasnobluelight.

LemonRx7-ChannelIntegratedTelemetryReceiver 9

PART 3. Additional Information for Advanced Users

A. PPM mode TherearetwoPPMmodes,providingdifferentchannelorders:

o PPM-JmodeprovidescPPMinJR/SpektrumTAERchannelorder(SOLIDBLUELED)

o PPM-FmodeprovidescPPMinFutaba/HitecAETRchannelorder(FLASHINGBLUELED)

ThecPPMsignalprovidedbythereceiverincludeschannels1to7andisavailableontheAUX1/PPMpins.WhenthereceiverisinPPMmode,PWMsignalsarenotavailableforindividualservos.

ForareceiverinServomode(bluelightOFF),PPMmodeisselectedasfollows:

1. Followthenormalbindprocedurefromstep1tostep3(seesection2B,page6above).DONOTremovethebindplugordisconnectpoweratthispoint.

2. Pressthereceiverbuttonforabout2seconds,untiltheFLASHINGblueLEDcomesON,indicatingPPM-Fmode(AETRchannelorder).TochangetoPPM-Jmode(TAERchannelorder)pressthebuttonagainforabout2seconds,untiltheSOLIDblueLEDcomesON.

3. Whentheappropriatestatusisachieved,disconnectthepowersourceandremovethebindplug.Thereceiver(evenifre-bound)remembersthesettinguntilitisdeliberatelychanged.

IfthereceiverisalreadyinPPMMode(bluelightONorFLASHING)themodecanbechangedorcancelledbyfollowingtheaboveprocessuntilthedesiredstateisachieved.

NotethatasatellitereceivercannotbeusedwhenthemainreceiverisinPPMmode.

B. RSSI TheRSSI(ReceivedSignalStrengthIndicator)numberissentbackfromthemodelbytelemetryanddisplayedinthe“A”fieldonthetransmitterscreen.Itrepresentsthestrengthoftheradiocontrolsignalavailablefromthereceiverfrontendforcontrolofthemodel.Itshouldreadcloseto100whenthereceiverisnexttothemodelandwilldropwithdistanceuntil,atavaluetypicallyaround30,thetelemetrysignalisnotstrongenoughandthedisplayfreezes.Thereceiverhasexcellentsensitivityandwillcontinuetooperatereliablywellbeyondthispoint.Indeed,LemonrecommendanRSSIreadingofnolowerthan20forsafeoperation,givinganideaofthemarginofsafetyinvolved.

Figure3.1–AnRSSIvalueof74displayedonaDX8screeninthe“A”field.

LemonRx7-ChannelIntegratedTelemetryReceiver 10

Theverticalbarsymbolinthetopleftshowsthattelemetryisliveandisbeingreceived.

WhileRSSIvaluesbelowabout30areunlikelytobeseenonthetransmittertelemetryscreen,theRSSIvoltagedisplayedonanOSD(On-ScreenDisplay)maycontinuetobevalidatmuchlowerlevels,asthisformofdisplaydoesnotrelyontherelativelylowpowertelemetrytransmissionfromthereceiver.

ChangesintheRSSIreadingcanbeconvenientlyexploredwiththetransmitterinRangeTestmode.NotethatputtingaSpektrumtransmitterintoRangeTestmodeattenuatesoutputpowerenoughtoreducerangebyafactorofabout30.3Thuseffectivecontrolat35m(120feet)inRangeTestmodeshouldtranslatetoabout1km(3600feet)rangeatfullpower.Thereare,however,manyvariablesinvolved,sotreatthisasonlyaroughguide.Thereisaverygoodprobabilitythatyouwillgetmuchgreaterrange.

TheLemonRSSInumberisarelativevalueandcannotbedirectlycomparedtoothersignalindicatorssuchasantennafadesreportedbySpektrumortheFrSkyRSSInumber.LemonhasstatedthatthemaximumsignalmeasuredaftertheLNAfrontendwhenthetransmitterandreceiverarerightnexttooneanotherisdisplayedasavalueof100.Adropin“RSSI”byoneunitcorrespondstoadropinsignalstrengthofapproximately0.6dBm.AttheLemonrecommendedminimumreadingof20thesignalistherefore0.6x80=48dBdown.Whilethereceiverhasalotofreservesensitivityandshouldcontinuetoworkevenbeyondthatpoint,itisnotrecommendedthatthisbetakenforgranted.

TestsinpracticalsituationsshowafairbitoffluctuationintheRSSIvalue(causedpresumablybychangingmodelandtransmitterorientationamongotherfactors),butitappearsthevaluefallsfairlysteadilyandapproximatelylinearlyfrom100to50thendropsoffmoreslowlybutstillinalinearfashionwithdistanceuntiltelemetrycutsoutatavaluearound30.

C. Antennas and Satel l ites ThisLemonreceiverisdescribedasfullrangeforbothcontrolandtelemetry.InfactthisreceiverhasaparticularlysensitiveLowNoiseAmplifier(LNA)frontendandshouldbettertherangeofothercomparableDSM2/DSMXreceiversunderthesameconditions.Howeverrangeisaffectedbythenumberofaerials(antennas)andtheirorientation,aswellasbytheinstallationinthemodel.

Thisreceiverhastwoactiveaerial(antenna)wires(thelast32mmofthecables)connectedtoaswitchthatselectsthestrongeravailablesignal.Thereceiverwillswitchantennasveryquicklyiftheoneitisusingstartstodropinsignalstrengthbelowtheotherantenna.Theswitchwilloccurwithin300mSandnosignalislostduringtheswitchingperiod.ThisantennaswitchingstrategyiscommonlycalledintheRCworld“Diversity”.

Thereceiveralsohasaconnectortoallowtheuseofasatelliteforadditionalsignalrobustness.Asatellitedoesnotincreasethemaximumpossiblerange.Rather,asaseparatestand-alonereceiveritincreasestheprobabilitythatareliablesignalwillbeobtainednomattertheorientationofthemodel.Themainreceiverselectsthestrongerofitsownbestsignalorthatofthesatellite.Notethatsatelliteswithdiversityantennasarenowavailable,givinguptofourseparatesignalsourcesforthereceiver/satellitecombination.

Theantennasweuseforradiocontrolradiate(andreceive)inalldirections,butthesignalismuchweakerofftheendsoftheantenna(theactiveportionofthecable)than"broadside"toit.Thinkofan

3Sincerangeisrelatedtothesquareofpower,toreducerangebyafactorof30requiresacutinpowerbyafactorofabout900.Rangetestpoweristhustypicallyaround0.1mw.

LemonRx7-ChannelIntegratedTelemetryReceiver 11

ancientnavalbattlewheretheshipshadverylittlefirepowerforeandaftbecausemostoftheircannonwerepointedoutthesides.

Toachievethemostreliablepossiblelinktothemodel,therefore,whatwewanttoavoidaresituationsinwhichthetransmitterandreceiverantennasareend-ontoeachother.Forthetransmitter,theadvicetothepilotissimple:don'tpointtheantennaatthemodel.Forthereceiver,thingsaremorecomplicatedbecausethemodelisconstantlychangingitsorientationinrelationtothetransmitter.Asinglereceiverantennawillinevitablybepointedatthetransmittersomeofthetime.

Thisiswherediversitycomesin.Ifthereceiverhastwoactiveantennaspositionedatrightanglestoeachother,theycanneverbothbepointedatthetransmittersimultaneously.Thereceiverjusthastoselecttheantennathatisgivingthebettersignalrightnow.That'swhatdiversityswitchingdoes.

DiversityimprovesthereliabilityoftheRFlinkinotherways.Ifthetworeceiverantennasarewellseparated,atleastoneshouldhaveaclearviewofthetransmitter,minimizingtheriskofsignalblanking.Aswell,withantennasatrightanglesoneofthemshouldberoughlyparalleltothetransmitterantenna,thusaligningpolarizationforastrongersignal.

Conductivematerialssuchasfoilcoverings,batteries,metalcomponentsandcarbonfibercanabsorbandshieldtheincomingradiosignal.2.4GHzsystemshaveaveryshortwavelengthandaresusceptibletothis.Receiveraerialsneedtobeplacedsothatthiseffectisminimized.

Whatallthismeansfortheinstallationofthereceiverissimple.Makesureitstwoantennasareseparatedasfaraspracticalfromeachotherandfromconductivestufflikebattery,wiringandcarbonfiber,andkeeptheactiveportions(thelast32mm)reasonablystraightandatrightanglestoeachother.

Ifasatelliteisconnectedforadditionaldiversity,itshouldbewellawayfromthemainreceiver,notrightnexttoit.Alignitsothesatelliteaerial(s)andatleastonemainreceiveraerialareatrightangles.

Don'tgetparanoid.Theinstallationdoesn'thavetobeperfecttosupportanadequatelystrongRFlink.Ourmodernreceiversdoaremarkablygoodjobofpickingupthesignal,evenwithjustasimplesingleantenna,sodiversitycanbethoughtofasextrasecurityforwhenthegoinggetstough.

D. Power Considerations Thistelemetry-integratedreceiverdrawsapproximately75mAwithnoservosconnected,asomewhathighercurrentthananormalreceiver.Forcomparison,theLemonDSMXCompatible7ChannelStabilizedReceiverdrawsabout55mAandtheLemonDSM2Compatible6ChannelFeatherLightReceiverdrawsabout25mA.Moreimportantly,theminimumoperatingvoltageoftheTelemetryreceiveris4.5Vcomparedto3.45VforotherLemonreceivers.ThismeansthatthisreceivercannotbeoperateddirectlyfromasingleLiPocellasusedinsomeDLGapplicationsbutmustuseeitheravoltageboosterorahighervoltagepack.

GivenLemon’srecommendedupperlimitof7.4v,thereceivershouldnotbepoweredbya2sLiPobattery(8.4Vfullycharged).AfourorfivecellNiMHbatteryora2sLiFebatterycanbeused.

E: Voltage Recal ibration Thereceiverispre-calibratedforvoltagesensingandavoltagesensingwireisprovidedasastandarditem.IftheoptionalV/Isensorisused,thevoltagesensingwireisnotrequired(seeSection3F,below).

Re-calibrationoftheexternalvoltagesensingofthereceiverisnormallynotrequired,butifitbecomesnecessary,pleasefollowtheprocedurelistedbelow.

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Figure3.2–VoltagesensorwireconnectedtobatteryV+.Firstbindplugisinnormalverticallocation,secondisinsertedhorizontallybetweenthetop(signal)pinsofAileronandRudderchannels.ThedevicewithascreenisaWattmeter,whichmeasuresvoltageandcurrentandisusedtoconfirmthebatteryvoltage.

Figure3.3–Batterynowpluggedin.Notevoltagesensorwire.Voltagesensoriscalibratedat8.43V,asshownonWattmeter.

Procedure 1. First,verifythatbothblueandgreenlightsonthereceiverareOFF.Ifnecessary,gobacktothe

instructionsforFailsafe(page7)orPPMMode(page9)andreset.

2. Withnopowerconnected,insertabindplugverticallyatbindlocation,asinthenormalbindprocedure.Insertasecondbindplughorizontallybetweenaileronandruddersignalpins(topones).

3. Connectthevoltagesensingwiretoan8.4Vsource.Afullychargedtwo-celllithium-polymer(LiPo)batterywillprovideanadequatelyaccuratereferencevoltage.SeeFigures3.2and3.3.

LemonRx7-ChannelIntegratedTelemetryReceiver 13

4. Withthetwo-cellbatterydisconnected,connectaspeedcontrol(ESC)withintegralBECtothereceiver.4Anyavailableservopinscanbeused(centerpinispositive,lowerpinisground).

5. ConnecttheESCtothetwo-cellLiPobattery.TheREDlightshouldbeflashingrapidlybeneaththereceivertoindicatebindmode.

6. Turnonthetransmitterinbindmodeapproximately1-2metersawayfromthereceiver.Thereceivershouldchangefromslowlyflashingtosteadyred,indicatingasuccessfulbind.Makesuretransmittertelemetryissetuptodisplaybatteryvoltage.

7. Pressthereceiverbuttonbriefly(lessthan1second).AGREENlightmeansthatthevoltagereadingiscalibrated.Thetransmittershoulddisplay8.3Vor8.4Vasbatteryvoltage.5

8. Pressandholdthereceiverbuttonforabout1.5seconds,untiltheBLUElightisturnedon.Thisindicatestothereceiverthatcurrentsensingisnotavailable.6

9. Turnoffthereceiverandremovebothbindplugstocompletevoltagecalibration.7Ifnecessary,resetFailsafeand/orPPMModetosuityoursetup.

F: Cal ibrating the Optional V/I Sensor TheLemonRxV/Isensingmoduleprovidesbothbatteryvoltageandcurrentsensing.ThereceiverisNOTpre-calibratedforusewiththeV/Imodule.ThefollowingcalibrationprocedureneedstobedoneoncewithanynewV/Isensorbeforeuse.Anadequatecalibrationcanbeperformedwithatwo-cellLiPobatteryandWattmeter.

Figure3.4–V/IsensorconnectedtobatteryV+withtwobindplugsinserted.ThedevicewithascreenisaWattmetertoconfirmtheactualbatteryvoltageandcurrent.

4Astand-alonebatteryeliminator(BEC/UBEC)orsuitablebatterycanalsobeusedtoprovidethenecessary4.5to7.4vpowerforthereceiver.5Notethat8.39vwilldisplayas8.3vbecauseofthelackofaseconddecimaldigitintheSpektrumtransmitterdisplay.Themoreprecisevalue,however,isusedinternallyandcanbeloggedontheSDcard.6IfthebuttonisreleasedbeforetheblueLEDcomeson,brieflypressthebuttonafewtimesuntilthebluelightisOFF.Thenstartsetupagainatstep7.7Ifcurrentmeasurementisrequired,itisnecessarytopurchasetheoptionalV/Isensor(seeSection3F).

LemonRx7-ChannelIntegratedTelemetryReceiver 14

Figure3.5–V/Isensorcalibratedat8.4Vand4A,asshownontheWattmeter.

Procedure 1. First,verifythatbothblueandgreenlightsonthereceiverareOFF.Ifnecessary,gobacktothe

instructionsforFailsafe(page7)orPPMMode(page9)andreset.

2. Withnopowerconnected,insertabindplugverticallyonthebindpins.Insertasecondbindplughorizontallybetweenaileronandruddersignalpins.

3. ConnecttheV/Isensortoafullychargedtwo-cellLiPobatterytoprovidethenecessary8.4Vsource.8Figure3.5showsthemeterconnectedinseries.Itmustbeabletomeasurecurrentofatleast5A.

4. Todrawanappropriatecurrentforcalibrationofthesensor,connecttheESCtoabrushlessmotorthatisknowntodrawmorethan4amps.Itmaybenecessarytoinstallapropelleronthemotortocreatethenecessaryload–beVERYcarefulifthisisdonetoensurethatthemotorissafelymounted.Besuretodisconnectthemotorwhenfinishedcalibration.

5. ConnecttheESCtothereceiverthrottlechannelpins.IftheESClacksaninternalBEC,aseparateBECcanbeusedtoprovidereceiverpower.

6. ConnecttheESC(andseparateBECifused)tothebattery.CheckthattheREDLEDbeneaththereceiverisflashingrapidlytoindicatebindmode.

7. Turnontransmitterinbindmodeapproximately1-2metersawayfromthereceiverwiththethrottlestickatlow.Thereceivershouldchangefromslowlyflashingtosteadyred,indicatingsuccessfulbind(seepage6fordetails).Makesuretransmittertelemetryissetuptodisplaybatteryvoltageandcurrent.

8. Pressthereceiverbuttonbriefly(lessthan1second).AGREENLEDmeansthevoltagereadingiscalibratedandcurrentsensingbiasissetat0A.Thetransmittertelemetrypageshoulddisplayeither8.3Vor8.4Vasbatteryvoltage9and0Aforcurrent.

8Thebatteryneedstobeabletosupplya4Acurrentwithoutunduevoltagedrop.Itisrecommendedthatthebatterybeatleast1000mAhwithatleast20Crating.

LemonRx7-ChannelIntegratedTelemetryReceiver 15

9. Movethethrottlesticktostartthemotor(becareful!)andadjustuntilthecurrentdrawshownonthemeterisascloseaspossibleto4.0A.

10. PressandholdthereceiverbuttonuntiltheBLUELEDturnson,indicatingthatcurrentsensingiscalibrated.10

11. Withthesystemstilldrawing4A,checkthatthetransmittertelemetrypageshowsacurrentreadingof3or4A.11

12. Turnoffthereceiverandremovebothbindplugstocompletevoltageandcurrentcalibration.Ifnecessary,resetFailsafeand/orPPMModetosuityoursetup.

HINT:Calibrationcanbedoneintwoparts.Thereceiverremembersthecurrentcalibrationvalueevenifyoudothevoltagecalibrationsubsequently.

Firstcalibratethecurrentvaluewithaconstant4Aload.Anybatteryfrom2sto6sthatiscompatiblewiththemotorandESCcanbeused.Gothroughsteps1to6,skipstep7,thencompletesteps8to10.

Nextdothevoltagecalibrationasinstep7,usingeithera2sbatteryoravariablevoltagesupply.

Finallygotostep11tocompletethecalibrationprocess.

G. Creating and Reading Telemetry Log Fi les Spektrumtelemetry-enabledtransmitterscanrecordalogfileofthedatasenttothetransmitterfromthereceiver.Thisiscontrolledentirelybythetransmitter;nosetupisrequiredonthereceiver.

Theoptionsavailableatthetransmitterspecifywhetherrecordingisenabled,ifso,howitistobestarted,andthenameoftheresultingfile.Refertoyourtransmittermanualforspecificinstructions.Youmaywanttoassignaswitchtostartandstoplogging,oryoumayprefertohaveitstartautomaticallyassoonasthethrottleisadvanced.

ThelogfilesaresavedontheSDcardinthetransmitter,alongwiththevariousmodelsetupfiles.Thelogfileshavethesamenameasthemodelfilesbutanextensionof.TLMratherthan.SPM.ToreadSpektrumlogfilesyouneedaprogramspecificallydesignedforthepurpose.Youcurrentlyhavetwochoices:

1) TheofficialSpektrumapprovedandsupportedSpektrumTelemetryViewersoftwarewrittenbyROBOSoftware.ItisavailableforbothWindowsandMac(OSX)andisavailableasa30daytrialandtopurchaseforUS$19.99here:http://www.robo-software.com

2) TheexcellentTlmviewerprogramwrittenbymodelerMikePetrichenko.ThisisafreeWindows-onlyprogramandavailableat:http://www.tlmviewer.com

HereisanexampleofaflightlogfromtheLemonreceiver,readandgraphedbyTlmviewer,showingthepackvoltageandcurrentduringa9-minuteflightofa1.8mspanelectricglider.

9Notethat8.39vwilldisplayas8.3vbecauseofthelackofaseconddecimaldigitintheSpektrumtransmitterdisplay.Themoreprecisevalueisusedinternallyandcanbelogged.10IfthebuttonisreleasedbeforetheblueLEDcomeson,brieflypressthebuttonafewtimesuntiltheblueLEDisoff,andthenstartPPMsetupagainatstep7.11Notethat3.9Awilldisplayas3AbecauseofthelackofaseconddecimaldigitintheSpektrumdisplay;this1Aprecisionisampleformostpurposes.Themoreprecisevalueisusedinternallyandcanbelogged.

LemonRx7-ChannelIntegratedTelemetryReceiver 16

Figure3.6–Tlmviewergraphofvoltage(green)andcurrent(orange)inflight.

ThisisthegraphofRSSIvaluesforthesameflight,whichwasouttoareasonablevisualrangelimit.

Figure3.7–TlmviewergraphofRSSIfromaproperlyinstalledreceiver.

NotehowthereareoccasionalplaceswheretheRSSIdropstozero.Thiswillbewherethetelemetrylinkwasmomentarilylost.HowevertheRSSIvaluerarelyfallsbelow50whenthedataisavailable.

FinallyhereisthesametypeofgraphfromasimilarflightwherethereceiverwaspoorlyinstalledwiththetwoantennaslyingalongsidetheLiPoandeasilyblanked.

LemonRx7-ChannelIntegratedTelemetryReceiver 17

Figure3.8–TlmviewergraphofRSSIfromapoorlyinstalledreceiver.

ThistimetheoverallRSSIvaluesarelowerandtherearenotonlyzerovaluesbutsignificantperiodswherethedataisobviouslymissingandthegraphingprogramhassimplyjoinedthevaluesateachendofthegap.Anexampleisbetween5:00and5:30min.Althoughthereareperiodswherethetelemetrytransmissionbacktothetransmitterhasfailed,theactuallyRSSIatthereceiverisstillstrongascanbeseenfromthevaluesjustbeforeandjustafterthetelemetrygap.Theweakertelemetryconnectionfromreceivertotransmitterhasbeenaffectedmuchmorebythepoorinstallationthanthecontrolconnectionfromtransmittertoreceiver.Thisisfurtherevidenceofthesensitivityofthereceiverandtherobustnessofthecontrollink.

Finally,Figure3.9showsexactlythesamedataexportedfromTlmviewerasa.csvfileandthenimportedintoMicrosoftExcel(whichallowsyoutomanipulatethepresentationformateasily)anddisplayedasapointscattergraph.Notethatdisplayingthedatathiswayshowsupthegapsinthetelemetrydatafeedwhenthemodelwasatextremerange.Acoupleofexamplesofsuchgapsarehighlightedinblueonthex-axis(whichExcelhasplottedinunitsof1/100secratherthanminutes).

Figure3.9–ExcelgraphicdisplayofpoorRSSIreadings(samedataasFig3.8).

LemonRx7-ChannelIntegratedTelemetryReceiver 18

H. Servo Output Timing

Most users can ignore this sect ion. This is technical information for those who need it . Thissectionisabouthowthereceiverputsouttheinformationforthecontrolchannels:allsevenatonce,oneaftertheother,orinsomedifferentmanner.

PWM InnormalPWM(PulseWidthModulation)mode,wheretheoutputforeachservoispresentonseparatepins,theLemonreceiverputsoutchannelpulsesintwobatches:

FirstChannels4,5and6–thatisRudder,GearandAux1–areoutputsimultaneously.

Then2.4mSlaterChannels1,2,3and7–Throttle,Aileron,ElevatorandAux2-areoutputtogether.

ThiscanbeseeninthelogictracedisplayshowninFigure3.10.NotethatChannel0onthelogictraceischannel1fromthereceiverandsoon.Thevaryingwidthofthepulsesthatrepresentscontrolinformationisclearlyvisible,withthefirstchannelneutral,thesecondatmaximum,andsoon.

Figure3.10–Logictracesofthe7outputchannelsfromtheLemonTelemetryreceiver.

Thisoutputschemeisdifferentfrommanyotherreceivers.ThemajorityoflowcostDSM2/DSMXreceiversoutputthechannelsoneafteranother(sometimesdescribedas“roundrobin”),butsomehigherendreceiverssynchronizeallorsomeofthepulsestoensuresimultaneoussignalsforservoactionsthatshouldoccuratthesametime.

Theadvantageofsimultaneoussynchronizedpulseoutputsisthatallservoactionsareinitiatedtogether.Theresultmaybenoticeableindemandingprecisionapplications,particularlyhelicopterrotormovements.Howevertheremaybeadownside,dependingontheservosused.Analoganddigitalservosloadthepowersupplyinadifferentway.Digitalservosarerefreshedatfixedintervals,withnoreferencetothetimingofincomingpulses.Thepowerpulsesaresentathighfrequencycomparedwiththeincomingcontrolpulses.Sotheyalwaysdrawpower,butatafairlyconsistentlyrate.

LemonRx7-ChannelIntegratedTelemetryReceiver 19

Bycontrast,analogservosonlydrivethemotorwhentheygetapulse,andtheydoitassoonastheygetthatpulse.Ifthecontrolpulserequirestheservotomovesignificantly,theresultmaybeademandforfullcurrent.Duringaggressiveflyingit’spossibleforseveralservostobecalledontochangepositionatthesametime,creatingahugedemandonthepowersupplyatthatinstant.

Theresultofthisdifferenceinfunctioningisthatonaveragethetotalcurrentforanalogservosmightbelowerthanforequivalentdigitals,buttheinstantaneouscurrentdrawcouldbeveryhigh.Itisthispeakcurrentthatcandepressthevoltageand“brown-out”thereceiver.

Inpractice,pulsetimingcanbeignoredbymostusers.However,forthoseseekingsimultaneouscontrolactionorsettingupanalogservosinlargemodelsandotherswithheavyservoloadsitisimportanttounderstandtheimplicationsofdifferentoutputtimingschemes.

cPPM Bydefinition,acPPMstreamconveysthecontrolpulsesinsequence.TheLemonTelemetryreceiveroffersachoiceofJR/Spektrumchannelorder(TAER)orFutaba/Hitec(AETR).

Figure3.11showsthecPPMstreamattheAux1/PPMpinonthereceiver.TheexamplehereisinFutaba/Hitecchannelorderandhaschannels1,5and6approximatelyatneutral,channel2atminimumandchannels3,4and7atmaximum.

TheLemonTelemetryreceiveroutputsonly7channelsonthePPMstream.SomeotherPPMreceiversoutputmorechannelsoncPPMthantheyactuallyhavePWMpins.

Figure3.11–OscilloscopetraceofcPPMoutput.

Note:Thisgraphisincludedsolelytoshowthenumberofchannelsanddisplayssomesignaldistortionduetomeasurementlimitations.Disregardthevoltagelevelsseenhere,aswellasthenoiseandovershoot.Aclean,noise-freehigh/lowpulseistobeexpectedfortheactualoutput.

LemonRx7-ChannelIntegratedTelemetryReceiver 20

NOTICE

ThismanualisprovidedtohelpyouunderstandandusetheLemonRx7-ChannelIntegratedTelemetryReceiver.TheauthorsarenotassociatedwithLemonRxandthisisnotaLemonRxpublication.

Youcanfreelyquotefrom,redistributeand/ormodifythismanual;indoingsopleaseacknowledgethesourceandanychanges.

Themanualisdistributedinthehopethatitwillbeuseful,butWITHOUTANYWARRANTY;withouteventheimpliedwarrantyofMERCHANTABILITYorFITNESSFORAPARTICULARPURPOSE.SeetheGNUGeneralPublicLicenseformoredetails.Inusingthismanual,youagreethatyouacceptallresponsibility.

Formoreinformation,see

http://www.rcgroups.com/forums/showpost.php?p=29707169&postcount=1

http://www.lemon-rx.com/shop/index.php?route=common/home

JJ604andDaedalus66

January2016

LemonTelemetryRxManualFeb9