GPS module



FrequentlyAskedQuestions

1.Whatisthemeaningof20channelsofGPSmodule?

TheGPSmodulehasaparameterofthenumberofchannels,suchas20channels,whichmeansthatthemodulecanestablishcommunicationwithupto20satellitesatthesametime.3satellitesare2Dpositioning,thedataisunstable,andthemoduleOnlyafterreceivingmorethan3satellitesignalsatthesametime,thecorrectpositioningdatacanbeobtainedaftercomplicatedcalculations.Ifthenumberofsatellitescommunicatingatthesametimeismore,themodulecanobtainpositioningdatafasterandmoreaccurately.Inanurbanenvironment,itisusuallypossibletocommunicatewith4to11satellitesatthesametime.

2.WhydoesittakealongtimetoobtainpositioningdataaftertheGPSmoduleisturnedon?

TheGPSmodulehascoldstart,hotstartandwarmstart(thecurrenttechnologyhasbasicallymadetheparametersofthecoldstartandwarmstartmodesveryclose,thusgraduallycancelingthewarmstart.Startup)threeparameters.IftheGPSmoduleispoweredonforthefirsttime,orwhenitispoweredonaftermovingmorethan500kilometers,themodulemustrecalculatetheephemerisdata.Undernormalcircumstances,theGPSmoduleonlyneedsmorethan30secondstobeabletolocatenormally(thisisColdstart),S-87hasabuilt-inbuttonbattery,whichcanstoretheephemerisdatainsidethemodule,anditcanbepositionedveryquicklywhenthemoduleisworkingnexttime.Generally,itonlytakes1~3secondstorealizeanewonelikeS-87Positioning,thenthistypeofpositioningiscalledahotstart.Ifthemoduleispoweredoffformorethan4hoursandtheinternalRTCdoesnothavereal-timepowersupply,thenturningonagainisequivalenttoacoldstart.

3.WhatshouldIdoifthelocationcannotbecold-startedforalongtime?

ThenyouneedtocheckwhethertheGPSantennaisplacedinanopenenvironment.CantheGPSdataoutputbytheGPSmoduleberead?CantheGPSsatellitesignalstatusbeobservedintheGSVsentenceintheGPSdata?Fromtheseaspects,wecanjudgewherethespecificproblemlies!Themodulecanoutputoncepersecond:$GPGGA$GPGSA$GPGSV$GPRMCpositioningdata,weusuallyuse$GPRMCtostreamlinethedatatooutputthisinformation,thisinformationcontainsthetarget:longitude,latitude,speed(nauticalmiles/hour),Themovementdirectionangle,year,month,hour,minute,second,millisecond,andpositioningdataareimportantinformationsuchaswhetherthepositioningdataisvalidorinvalid.MostoftheGPSmodulechipsaremainlybasedontheSiRFIIIseries,whichistheworld'slargestmarketshare,andtheSiRFIIIchipItis20channelsandhasstrongreal-timesolvingability.Thispartofthemoduleisverycommononthemarket:Huantian,Dagamma,Ublox,etc.

4.Whataboutantennastatusmonitoring?

WhatshouldIdowhentheantennaisopenandshort-circuited?ThebestwayisthattheGPSmodulecanoutputthestatementoftheopenandshortcircuitstatusoftheantennatopromptthecustomertodothisinspection.Theadvantageofthisisthatthecustomercaneasilychecktheproblempoints,andatthesametimeprotectthemodulefromtheimpactoflargecurrents.Manysuchapplications,suchasS-87,S-90,S-93andUBLOX,somemodulesalsohavethisfunction,butthedifferenceisthatUbloxneedstobeequippedwithperipheraldevicestoachievethisfunction,andgammadoesnotrequireanyperipherals.Forthedevice,itseemsthatthisfunctioncanonlyberealizedbytheflashversion,andtheROMversioncannotbeconfiguredwithIOports,sothisfunctioncannotberealized.

Specifications

SeriesGPSmodulesintegratehighsensitivity,lowpowerconsumption,GPSchipsetsolutions,inacompactdesign.Cantrackupto20satellitesatthesametime,andquicklydetermine,1Hznavigationupdate.ItiswidelyusedinPDAs,personaldigitalassistants,navigators,mobilephones,computersorotherbattery-operatednavigationsystems.

Basicparameters

Receiving20channelsofGPSreceivertype,L1frequency,1.023MHzchipspeed,C/Acode1.023MHzchipspeed

Horizontalpositioningaccuracy<2.5m,<2.0m(WAAS),(50%,24hoursstatic,-130dbm)

Speed​​accuracy<0.01m/s(highspeed)<0.01°(heading),(50%@30m/s)

Thetimeaccuracyis1microsecondtosynchronizetheGPStime

ttff(timeisset)hotstartfor1S(50%,-130dbm,automatic)hotstart,warmstart35s,coldstart:42s

Sensitivitytracking-159dbm

Dynamicconditionaltitude<18,000meters(60,000feet)

Speed<515m/s(1000nauticalmiles),acceleration<4g

Technicalparameters

Powermainpowerinput3.3VDC,powersupplycurrent<80mA

SupportprotocolmessageNMEA-0183,SIRFbinary

ThedefaultNMEAgga,GSA,gsv(GLL,VTG,andZDAoptional)

Baudrate4800baudrate(otherratesareoptional)

EnvironmentalcharacteristicsOperatingtemperaturerange-40oCto+85oC,

Storagetemperaturerange-45oCto+100oC

Appearanceparameters

Size13×15×2.4cubicmillimeters

Weight<4grams

Performancedescription

High-sensitivityGPSchipset

High-performancereceivertracksupto20satellites

TTLoutputforGPScommandinterface

Lowpowerconsumption

Theaveragecoldstarttimeis35seconds.

1MBofchipSRAMmemory

Thetimetoregaininformationis0.1seconds

Supportaccurate1ppsTheoutputsignalisconnectedtoGPScalibration

SupportstandardNMEA-0183andSIRFbinaryprotocol

Multipathmitigationhardware

Easytointegrateintohandhelddevices

1.NMEA0183standardsentences

1.GlobalPositioningSystemFixData(GGA)GPSpositioninginformation

$GPGGA,<1>,<2>,<3>,<4>,<5>,<6>,<7>,<8>,<9>,M,<10>,M,<11>,<12>*hh

<1>UTCtime,hhmmss(hour,minute,second)format

<2>Latitudeddmm.mmmm(degreesandminutes)format(theleading0willalsobetransmitted)

<3>LatitudehemisphereN(NorthernHemisphere)orS(SouthernHemisphere)

<4>Longitudedddmm.mmmm(degreesandminutes)format(theleading0willalsobetransmitted)

<5>LongitudehemisphereE(eastlongitude)orW(westlongitude)

<6>GPSstatus:0=notpositioned,1=non-differentialpositioning,2=differentialpositioning,6=estimating

<7>isusingthesatellitetocalculatethepositionQuantity(00~12)(Thepreceding0willalsobetransmitted)

<8>HDOPlevelprecisionfactor(0.5~99.9)

<9>Altitude(-9999.9~99999.9)

<10>Theheightoftheearth'sellipsoidrelativetothegeoid

<11>Differentialtime(thenumberofsecondssincethelastreceiveddifferentialsignal,Ifitisnotfordifferentialpositioning,itwillbeempty)

<12>DifferentialstationIDnumber0000~1023(thepreceding0willalsobetransmitted,ifitisnotfordifferentialpositioning,itwillbeempty)

2.GPSDOPandActiveSatellites(GSA)currentsatelliteinformation

$GPGSA,<1>,<2>,<3>,<3>,<3>,<3>,<3>,<3>,<3>,<3>,<3>,<3>,<3>,<3>,<4>,<5>,<6>*hh

<1>mode,M=manual,A=automatic

<2>positioningtype,1=nopositioning,2=2Dpositioning,3=3Dpositioning

<3>PRNcode(pseudo-randomnoisecode),thesatellitenumberbeingusedtocalculatetheposition(01~32,theleading0willalsobetransmitted).

<4>PDOPpositionprecisionfactor(0.5~99.9)

<5>HDOPlevelprecisionfactor(0.5~99.9)

<6>VDOPverticalaccuracyfactor(0.5~99.9)

3,GPSSatellitesinView(GSV)visiblesatelliteinformation

$GPGSV,<1>,<2>,<3>,<4>,<5>,<6>,<7>,...<4>,<5>,<6>,<7>*hh

<1>ThetotalnumberofGSVsentences

<2>TheGSVnumberofthissentence

<3>Thetotalnumberofvisiblesatellites(00~12,thefirst0Willalsobetransmitted)

<4>PRNcode(pseudo-randomnoisecode)(01~32,theleading0willalsobetransmitted)

<5>satelliteelevationangle(00~90degrees,thefirst0willalsobetransmitted)

<6>Satelliteazimuth(000~359degrees,thefirst0willalsobetransmitted)

<7>Signal-to-noiseratio(00~99dB,whenthesatelliteisnottracked,itwillbeempty,andthepreceding0willalsobetransmitted)

Note:<4>,<5>,<6>,<7>Theinformationwillbedisplayedcyclicallyaccordingtoeachsatellite,andeachGSVsentencecandisplayupto4satelliteinformation.OthersatelliteinformationwillbeoutputinthenextsequenceofNMEA0183sentences.

4,RecommendedMinimumSpecificGPS/TRANSITData(RMC)recommendedpositioninginformation

$GPRMC,<1>,<2>,<3>,<4>,<5>,<6>,<7>,<8>,<9>,<10>,<11>,<12>*hh

<1>UTCtime,hhmmss(hour,minute,second)format

<2>Positioningstatus,A=validpositioning,V=invalidpositioning

<3>latitudeddmm.mmmm(degreesandminutes)format(theleading0willalsobetransmitted)

<4>LatitudeHemisphereN(NorthernHemisphere)orS(SouthernHemisphere)

<5>Longitudedddmm.mmmm(degreesandminutes)format(theleading0willalsobetransmitted)

<6>LongitudehemisphereE(eastlongitude)orW(westlongitude)

<7>Groundspeed(000.0~999.9knots,thefirst0willalsobetransmitted)

<8>Groundheading(000.0~359.9degrees,basedontruenorth,thefirst0willalsobetransmitted)

<9>UTCdate,ddmmyy(day,month,year)format

<10>Magneticdeclination(000.0~180.0degrees,theleading0willalsobetransmitted)

<11>Magneticdeclinationdirection,E(East)orW(West)

<12>Modeindication(onlyNMEA0183version3.00output,A=autonomouspositioning,D=Differential,E=estimate,N=invaliddata)

5,TrackMadeGoodandGroundSpeed​​(VTG)groundspeedinformation

$GPVTG,<1>,T,<2>,M,<3>,N,<4>,K,<5>*hh

<1>Groundheadingbasedontruenorth(000~359degrees,thefirst0willalsobetransmitted)

<2>Groundheadingbasedonmagneticnorth(000~359degrees,thefirst0willalsobetransmitted)

<3>Groundrate(000.0~999.9knots,thefirst0willalsobetransmitted)

<4>Groundspeed(0000.0~1851.8km/h,thefirst0willalsobetransmitted)

<5>Modeindication(onlyNMEA0183version3.00output,A=autonomouspositioning,D=differential,E=estimation,N=Invaliddata)

6,GeographicPosition(GLL)positioninggeographicinformation

$GPGLL,<1>,<2>,<3>,<4>,<5>,<6>,<7>*hh

<1>latitudeddmm.mmmm(degreesandminutes)format(theleading0willalsobetransmitted)

<2>LatitudeHemisphereN(NorthernHemisphere)orS(SouthernHemisphere)

<3>Longitudedddmm.mmmm(degreesandminutes)format(theleading0willalsobetransmitted)

<4>LongitudehemisphereE(eastlongitude)orW(westlongitude)

<5>UTCtime,hhmmss(hours,minutes,andseconds)format

<6>Positioningstatus,A=validpositioning,V=invalidpositioning

<7>Modeindication(onlyNMEA0183version3.00output,A=autonomouspositioning,D=differential,E=estimation,N=Invaliddata)

2.SentencesdefinedbyGARMIN

7,EstimatedErrorInformation(PGRME)estimatederrorinformation

$PGRME,<1>,M,<2>,M,<3>,M*hh

<1>HPE(horizontalestimationerror),0.0~999.9meters

<2>VPE(Verticalestimationerror),0.0~999.9meters

<3>EPE(positionestimationerror),0.0~999.9meters

8,GPSFixDataSentence(PGRMF)GPSpositioningInformation

$PGRMF,<1>,<2>,<3>,<4>,<5>,<6>,<7>,<8>,<9>,<10>,<11>,<12>,<13>,<14>,<15>*hh

<1>GPSweekNumber(0~1023)

<2>GPSseconds(0~604799)

<3>UTCdate,ddmmyy(day,month,year)format

<4>UTCtimeinhhmmss(hours,minutesandseconds)format

<5>GPSjumpseconds

<6>latitudeddmm.mmmm(degreesandminutes)format(frontThe0willalsobetransmitted)

<7>LatitudeHemisphereN(NorthernHemisphere)orS(SouthernHemisphere)

<8>Longitudedddmm.mmmm(degreesandminutes)format(Thefirst0willalsobetransmitted)

<9>LongitudehemisphereE(eastlongitude)orW(westlongitude)

<10>mode,M=manual,A=Automatic

<11>positioningtype,0=nopositioning,1=2Dpositioning,2=3Dpositioning

<12>groundspeed(0~1851km/h)

<13>Groundheading(000~359degrees,withtruenorthasthereferencedatum)

<14>PDOPpositionprecisionfactor(0~9,roundedup)

<15>TDOPtimeprecisionfactor(0~9,roundedup)

9,MapDatum(PGRMM)coordinatesysteminformation

$PGRMM,<1>*hh

<1>Thenameofthecurrentlyusedcoordinatesystem(datalengthisvariable,suchas"WGS84")

Note:ThisinformationisincontactwithMapSourceItisusedwhenreal-timeconnectionismade.

10,SensorStatusInformation(PGRMT)workingstatusinformation

$PGRMT,<1>,<2>,<3>,<4>,<5>,<6>,<7>,<8>,<9>*hh

<1>Productmodelandsoftwareversion(datalengthisvariable,suchas"GPS15L/15HVER2.05”)

<2>ROMverificationtest,P=pass,F=fail

<3>Receiverdiscontinuousfailure,P=pass,F=Failure

<4>Storeddata,R=Keep,L=Lost

<5>Clockinformation,R=Keep,L=Lost

<6>Oscillatordiscontinuousdrift,P=pass,F=excessivedriftdetected

<7>Dataisdiscontinuouscollection,C=collecting,ifthereisnocollectionthenitisEmpty

<8>GPSreceivertemperatureindegreesCelsius

<9>GPSreceiverconfigurationdata,R=Keep,L=Lost

Note:Thissentenceissenteveryminute,regardlessoftheselectedbaudrate.

11,3DvelocityInformation(PGRMV)three-dimensionalvelocityinformation

$PGRMV,<1>,<2>,<3>*hh

<1>Eastdirectionspeed,514.4~514.4m/s

<2>Northdirectionspeed,514.4~514.4m/s

<3>Upwardspeed,999.9~9999.9meters/second

12,DGPSBeaconInformation(PGRMB)beacondifferentialinformation

$PGRMB,<1>,<2>,<3>,<4>,<5>,K,<6>,<7>,<8>*hh

<1>Beaconstationfrequency(0.0,283.5~325.0kHz,Theintervalis0.5kHz)

<2>Beaconbitrate(0,25,50,100or200bps)

<3>SNRbeaconsignaltonoiseratio(0~31)

<4>Beacondataquality(0~100)

<5>Thedistancefromthebeaconstationinkilometers

<6>Thecommunicationstatusofthebeaconreceiver,0=checkwiring,1=nosignal,2=tuning,3=receiving,4=scanning

<7>differentialSource,R=RTCM,W=WAAS,N=Non-differentialpositioning

<8>Differentialstate,A=Auto,W=WAASonly,R=RTCMonly,N=DonotreceivedifferentialSignal

Introduction

TheGPSpositioningmoduleweoftensayiscalledtheuserpart.ItreceivesanddemodulatesthebroadcastC/Acodesignalofthesatellitelikea"radio".Thecenterfrequencyis1575.42MHz.TheGPSmoduledoesnotbroadcastsignalsandispassivepositioning.Bycalculatingthepseudo-distancetoeachsatellite,thefourparametersoflongitude,latitude,altitudeandtimecorrectionofthereceiverareobtainedbythedistanceintersectionmethod.Thecharacteristicisthatthepointspeedisfast,buttheerrorislarge.Themoduleforinitialpositioningrequiresatleast4satellitestoparticipateinthecalculation,whichiscalled3Dpositioning.3satellitescanachieve2Dpositioning,buttheaccuracyisnotgood.TheGPSmodulecontinuouslyoutputspositioninginformationandauxiliaryinformationinNMEAformatthroughtheserialcommunicationportforthereceivertochooseandapply.

ThemostimportantindicatorsofGPSmoduleperformanceincludereceivingsensitivity,positioningtime,locationaccuracy,powerconsumption,timeaccuracy,etc.Themodulestartuppositioningtimeisverydifferentindifferentstartupmodes.Generallyspeaking,coldstarttimereferstothesituationwherethereisnodatathatishelpfulforpositioninginthemodule,includingephemeris,time,etc.,generallynominallywithin1minute;warmstarttimemeansthattherearenewersatellitesinsidethemoduleEphemeris(generallynomorethan2hours),butthetimedeviationisverylarge,generallynominallywithin45seconds;thehotstarttimereferstothesituationwheretheshutdowndoesnotexceed20minutes,andtheRTCtimeerrorisverysmall.Generally,itisnominallywithin10seconds;therecapturetimeislikeacargoingthroughatunnelandrecapturethesatellitewhenitexitsthetunnel.Generally,itisnominallywithin4seconds.

Ifthemoduleisplacedforalongtimeafterpositioning,orthemoduleistransportedhundredsofkilometersawayafterpositioning,thereisanephemerisinsidethemodule,butthisephemerisiswrongorhasnoreferencesignificanceof.Inthesecases,thepositioningtimemaytakeseveralminutesorevenlonger.Therefore,whentheGPSmoduleleavesthefactory,theephemerisandotherdatainsidethemoduleshouldbecleared,sothatthecustomercanquicklylocatethemodulebycoldstartaftergettingthemodule.

Thepositioningaccuracycanbeinvestigatedunderstaticanddynamicconditions,andthedynamicpositioningeffectisbetterthanstaticpositioning.ThenominalpositioningparametersoftheGPSmodulearemeasuredunderacompletelyopenskywithgoodsatellitesignals.Therefore,itisdifficulttoachievethenominalpositioningtimeandpositioningaccuracyinconventionaltests.Therearetwocommonwaystodescribetheaccuracyofhorizontalpositioning:oneis?mCEP,whichisthecircularprobabilityerror,whichmeansthatthemeasuredpointhasa50%probabilityofbeinglocatedinacirclewiththerealcoordinateasthecenterand?mastheradius;Itis?m2DRMS,thatis,2timesthehorizontalrooterror,whichmeansthatthemeasuredpointhasaprobabilityofabout95.5%inacirclecenteredontherealcoordinatesandaradiusof?m.

Accuracy

ThepositioningaccuracyoftheGPSmoduledependsonmanyaspects,suchasthesatelliteclockandorbitdifferencefromtheGPSsystem,thenumberandgeometricdistributionofvisibleGPSsatellites,solarradiation,Atmosphere,multipatheffects,etc.Inaddition,thesameGPSmodulemaycausedifferentpositioningerrorsduetoantennaandfeederquality,antennapositionanddirection,testtimeperiod,openskyrangeanddirection,weather,PCBdesign,etc.EvenwhendifferentGPSmodulesofthesamemanufacturerandthesamemodelaretestedatthesametimeusingantennadiversity,thestaticdriftwillbedifferent.

TheGPSmoduleisoftenusedasatimereferenceinpracticalapplications.WiththeRTCinsidethemodule,averyhigh-precisiontimereferencecanbeobtained,whichprovidesgreatconvenienceforproductdesign.AsforGPSspeedmeasurement,itisonlyanextendedapplicationbasedonobtainingthelatitudeandlongitudeandperformingsimplecalculations.

ThecommonantennaofGPSisaceramicflatpanelantenna.Thiskindofantennahaslowcost,andanactiveamplifiercircuitisaddedexternally,thereceivingsignaldirectionissingle,andthegainisrelativelyhigh,soitismostused.Butitsdisadvantageisthatitislargeinsizeandsusceptibletofrequencydriftduetotemperature.Iftheceramicareaismadesmall,itwillaffectthereceivinggain;ifitismadethin,itwillaffectthereceivingbandwidthofthereceivingantenna,anditwillalsobeaffectedbytheactiveamplificationpart.Thesizethatworkswellatpresentis25×25×4mm3.Theceramicchipantennaworksbestwhenplacedverticallyupwardsinactualuse.

ThesignaltransmissionlineofGPSantennaisalsoveryimportant,includingexternalfeederandPCBtrace.Theoutputpowercanbemaximizedonlywhentheimpedanceismatched.Therefore,theentiretransmissionlinemustensureahigh-frequencyimpedanceof50Ω.ForhowtodesigntheRFtraceimpedanceonthePCB,somesmallsoftwarecanhelpyoucalculateitveryconveniently.

Problemanalysis

  1. Whatisthemeaningof16channelsofGPSmodule?TheGPSmodulehasaparameterofthenumberofchannels.Forexample,thelatestmodelis16channels,whichmeansthatthemodulecanestablishcommunicationwithupto16satellitesatthesametime.Themodulecanonlyobtainthecorrectsignalafterreceivingmorethan3satellitesignalsatthesametime.Ifthenumberofsatellitescommunicatingatthesametimeismore,themodulecanobtainthepositioningdatafasterandmoreaccurately.Onthesurfaceoftheearth,itispossibletocommunicatewith16satellitesatthesametimeonlywhenthegeographicalconditionsareparticularlyideal.Itisusuallypossibletocommunicatewith4to8satellitesatthesametimeundertheenvironment.

  2. WhydoesittakealongtimetoobtainpositioningdataaftertheGPSmoduleisturnedon?TheGPSmodulehastwoparameters:coldbootandhotboot.IftheGPSmoduleispoweredonforthefirsttime,orwhenitispoweredonaftermovingmorethan1,000kilometers,themodulemustrecalculatetheephemerisdata,whichusuallytakes1to5minutes,andthenstoretheephemerisdatainInsidethemodule,dataisstoredbythelithiumbatteryinsidethemodule.Thisiscalledcoldbootandtakesalongtime.Ifyouturnonthenexttime,becausethelithiumbatteryhassavedvalidephemerisdata,itcanquicklylocate,usuallywithin30seconds,soitiscalledhotboot.Ifthemoduleispoweredoffformorethan10hours,thelithiumbatteryisdischargedandthendischarged.Bootingisalsoequivalenttocoldbooting.

  3. WhatshouldIdoifIcan’tcoldbootforalongtime?Onlyinrarecases,itwillnotbeabletostartcoldformorethan15minutes.Atthistime,theproblemcanbesolvedbypoweringoffthemoduleagainormovingtheGPSantennaforacertaindistance.Ofcourse,theGPSantennamustbeplacedinarelativelyopenplaceoutdoors.Toreceivesatellites!ThisisthedataoutputwhentheGPSmoduleisturnedonandnovalidpositioningdataisobtained.TheGPSmoduleoutputsoncepersecond:$GPGGA$GPGSA$GPGSV$GPRMCpositioningdata,weusuallyuse$GPRMCtostreamlinethedatatooutputthisinformation,thisinformationcontainsTheimportantinformationofthetarget:longitude,latitude,speed(nauticalmile/hour),movementdirectionangle,year,month,hour,minute,second,millisecond,andwhetherthepositioningdataisvalidorinvalid.TheabovefigureshowsthatthereisnopositioningSuccess,sothedataisinvalid.

  4. WhatisthedifferencebetweenGPSandGPRS:GPSisaglobalsatellitepositioningsystemdevelopedbytheUnitedStates.Justlikemycountry'sBeidou,Russia'sGLONASS,andEurope'sGalileo,GPRSisusedforpositioning.ItisamobiledataserviceavailabletoGSMmobilephoneusers,commonlyknownasthe2.5-generationcommunicationsystem.

Mainfailure

NO.1Thefirstphenomenonisthatthemoduledoesnotworkatall.

TherearemanyaspectstothissituationThereasonwillappear.Firstofall,youmustmeasurethepinvoltage.Thisistheeasiestandeasiestwaytojudge.Ifthemoduleisfromanunknownsource,itisnecessarytoconsiderwhetheritisdamagedbyaninternalshortcircuit.Itisnecessarytoconsiderwhetheritisabadproduct,etc.,whichshouldalsobeconsideredasakeypoint.

Generallyspeaking,ifqualityproblemsaresuspected,thepossibilityofaformalagencyforbrand-namecomponentswillberelativelysmall,butifForproductsboughtfromtheelectronicmarket,thesourceofsupplymustfirstbeconsidered.Inthiscase,experimentingistantamounttoworseningthesituation.

Ifitisashortcircuit,youcantakethecurrentmeasurementmethod.IfitisnotconvenienttotestCurrent,youhavetocheckwhetheranycomponentormoduleonthePCBbottomplateshowssignsofheating.Fortheheatingpart,carefullyanalyzethepossibility.

Duringtheweldingprocessofu-bloxproductsintheexperiment,Theremaybeashortcircuitatthebottomofthehand-solderedmodulebutitcannotbeobservedwiththenakedeye.Atthistime,youmustcarefullyuseamultimetertotestwhetherthereisashortcircuitbetweentwoadjacentpins.Ifthisoccurs,thepartwillalsoheatup.OfcourseYoumustalsolineupifthereisnoshortcircuitontheperiphery.Atthistime,youshoulduseasolderingirontoheatthepartandre-fluxtosolder.Sometimestheshortcircuitisatthebottom,andtheremaybetoomuchsolder.Atthistime,youneedtouseahotairguntoremovethemodulefromthebottom.Solderingthedisassembledmodule,andthenre-soldering,mustpaystrictattentiontovarioustemperaturecontrolsduringwelding,themaximumtemperatureofthemodulecannotexceed250degreesfor10seconds,andrememberthatalloperatingproceduresmustbecorrect.Inordertomakethedamagerateofthemoduleintheexperimentaslowaspossible.

Generallyspeaking,ifthecircuititselfismature,itisimportanttoconsidertheabove-mentionedbottomshort-circuitweldingproblem.Afterthereplacement,ifthevoltageofeachpiniscorrect,Inprinciple,thepossibilityofpassingwillbegreater.

NO.2ThesecondphenomenonisthatthemodulevoltageisnormalbutthereisnoNMEAcodeoutput

ThereasonforthissituationmaybeThereisno3VvoltageappliedtotheTTLlevelVCCsupplyterminal.Firsttestwhetherthepinconnectionisnormal.Generallyspeaking,itisrelatedtotheTTLlevelcircuit.

NO.3Thethirdphenomenonisthemodule.ThevoltageisnormalandthereisNMEAoutputbutnopositioninginformation.

Therearemanysituationsinthissituation,butthefollowingsituationisthatthemachineisplacedoutdoorsduringthetest,andthesignalstrengthisnotconsidered.

IfIfitisapassiveantenna,youshouldpayattentiontowhethertheperipheralcircuitiscorrectwhenusingitoutdoors.

Ifyouareusinganexternalactiveantenna,BesuretoconsiderwhethertheRF[_]INpinhasa3Vpowersupplyvoltage.Ifnot,the3VpowersupplycircuitoftheRFpartisnotprovided.FocusonthepowersupplypartoftheRFpart.

NO.4ThethreephenomenaarethatthemodulevoltageisnormalandthereisNMEAoutputbuttheUSBinterfacecannotbeusedforcommunication.

Inthiscase,themainconsiderationiswhethertheUSBpowersupplyterminalofthemoduleisnormal,whethertheDP+/DP-datalineisconnectedreversely,andThereisasituationthatitsprotectiontubeisclampedordamaged.Inanemergency,theprotectiondiodecanberemovedfirstforcommunicationoperations,andthenspecificexperimentswillbeperformedlater.

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