Owner's manual

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NAV440UserManual
7430‐0131‐01Rev.F
Page37
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Signals
Extern )alGPSAiding(PortB,VG440andAHRS440
NOTE:ThisfeatureonlyappliestoVG440andAHRS440.
NOTE:TheGPSserialcommunicationportshouldbeconfiguredto8databits,1startbit,1stopbit,noparitybit,
andnoflowcontrol.
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TheVG4
40/AHRS440allowsusinganexternalGPSreceiver.Todoso,thefollowingactionsarerequired:
• TheexternalGPSreceivermustbeconfiguredtooutputtheGPSmessagestobecompatiblewiththe440
Series.Table10belowshowsthesupportedGPSprotocolsandguidelinesforconfiguration.Thedetailsof
theGPSmessagescanbefoundintherespectiveGPSprotocoldocuments.
• TheVG/AHRS440mustbeconfiguredtoacceptexternalGPSinformation.Referto
Table10belowand
Chapter7.Configuringthe440SerieswithNAVVIEW2.2.
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Table10ConfigurationforExternalGPSReceiverforVG440/AHRS440
Protocols RequiredMessages RequiredMessageRate Baudrate
Ubloxbinary
NAV‐LLH,NAV‐VELNED,
NAV‐STATUS
4Hz
9600,19200,38400,57600
$
NovAtelOEM4
OEMVBinary
and
BestPosB,BestVelB 4Hz
9600,19200,38400,57600
$
NovAtel
ASCII
OEM4
PosVelNavDopA 4Hz
19200,38400,57600
$
NMEA* GPGGA,GPVTG 4Hz
9600,19200,38400,57600
$
*Notrecommendedforairborneapplications.
$
57600 is the preferred baud rate for optimum performance
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IftheVG/AHRS440isparsingvalidexternalGPSdataandtheGPSreceiverhas3Dlock,thenthe
Chapter11.BuiltInTest(BIT) 
comStatusÆnoExternalGPSflagwillbezero,otherwiseitwillbeone.Referto onpage
93fordetailsaboutsystemstatusindications.
AstheNMEAprotocoldoesnotprovideverticalvelocity,theverticalvelocitythe440Seriesestimates(basedupon
GPSalt
itudechanges)maynotbesufficientforairborneapplications.
NOTE:TheNMEAprotocolisnotrecommendedforairborneapplications
HardwareBITErrorOutput
ThehardwareBITerroroutputpinistheultimateindicationofsystemfailure.Thisindicationisavailableinmost
softwareoutputpacketsasthemasterFailflag.ItisthelogicalANDofthehardwareError,comError,andsoftware
Errorflagsmonitoredbythesystem.Intheeventofacommunicationfailure,thehardwareBITerrorpinmaybe
usedtodetectamasterFailassertion.Thispinisopen‐collectorandrequiresa1kto10kohmpull‐upresister.The
systemwilldrivethispinlowtoassertasystemfailure.