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)
Speedaccuracy<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
Whatisthemeaningof16channelsofGPSmodule?TheGPSmodulehasaparameterofthenumberofchannels.Forexample,thelatestmodelis16channels,whichmeansthatthemodulecanestablishcommunicationwithupto16satellitesatthesametime.Themodulecanonlyobtainthecorrectsignalafterreceivingmorethan3satellitesignalsatthesametime.Ifthenumberofsatellitescommunicatingatthesametimeismore,themodulecanobtainthepositioningdatafasterandmoreaccurately.Onthesurfaceoftheearth,itispossibletocommunicatewith16satellitesatthesametimeonlywhenthegeographicalconditionsareparticularlyideal.Itisusuallypossibletocommunicatewith4to8satellitesatthesametimeundertheenvironment.
WhydoesittakealongtimetoobtainpositioningdataaftertheGPSmoduleisturnedon?TheGPSmodulehastwoparameters:coldbootandhotboot.IftheGPSmoduleispoweredonforthefirsttime,orwhenitispoweredonaftermovingmorethan1,000kilometers,themodulemustrecalculatetheephemerisdata,whichusuallytakes1to5minutes,andthenstoretheephemerisdatainInsidethemodule,dataisstoredbythelithiumbatteryinsidethemodule.Thisiscalledcoldbootandtakesalongtime.Ifyouturnonthenexttime,becausethelithiumbatteryhassavedvalidephemerisdata,itcanquicklylocate,usuallywithin30seconds,soitiscalledhotboot.Ifthemoduleispoweredoffformorethan10hours,thelithiumbatteryisdischargedandthendischarged.Bootingisalsoequivalenttocoldbooting.
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.
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.