Owner's manual
Page36
NAV440UserManual
7430‐0131‐01Rev.F
J2—GPSAntennaConnector
TheGPSreceiverneedstoreceivesignalsfromasmanysatellitesaspossible.AGPSreceiverdoesnotworkproperly
innarrowstreetsandundergroundparkinglotsorifobjectsorhumanbeingscovertheantenna.Poorvisibilitymay
resultinpositiondriftoraprolongedTime‐To‐First‐Fix(TTFF).Agoodskyvisibilityisthereforeaprerequisite.
Eventhebestreceivercannotcompensateforsignallossduetoapoorantenna,in‐bandjammingorapoorRFcable.
TheunitshipswithanexternalactiveantennathatmustbeconnectedproperlytoSMAjackontheunitcase.Placing
theantennaona16squareinchorlargergroundplaneishighlyrecommended.
I/OPortInterface
PortA:User(computer),RS232serialdatainterface
TheserialinterfaceisstandardRS‐232,9600,19200,38400,or57600baud,8databits,1startbit,1stopbit,no
parity,andnoflowcontrolandwilloutputatauserconfigurableoutputrate.Thesesettingsallowinteractionviaa
standardPCserialport.
PortB:GPSInterface,RS232serialinterface
PortBcanbeappliedtointernalorexternalGPSinterface.
InternalGPS
TheinternalGPSreceiveroftheNAV440outputsdatainNMEA‐0183formatasdefinedbytheNationalMarine
ElectronicsAssociation(NMEA),StandardForInterfacingMarineElectronicDevices,Version2.20,January1,1997.
noflowcontrol.
Thepacketsaresentat9600Baud,8databits,1startbit,1stopbit,noparitybit,and
GPSmessagesaredeliveredinNMEAmessageformat.Formoreinformation,referto
AppendixA.NMEAMessage
Format
onpage103.
ExternalGPS
ExternalGPSissupportedviaVG440andAHRS440functions.Forthe440Seriesunittointerfacewithanexternal
GPSreceiver,theGPSreceivermustbeconfiguredtooutputdatainaformatcompatiblewiththe440Seriesunit.
ormatsaredescribedinthenextsection:
F
ExternalGPSAiding(PortB,VG440andAHRS440)onpage37.
CableFieldRequirements
The440SeriesisshippedwithanEMIfilterattachedtotheDB‐15Connector.Thisconnectormustremaininplace
toensurep
ropershieldingfromEMIinterference.
CAUTION:Thecablesentwiththeunitisintendedtoprovidetheuserwiththeabilitytotesttheunitrightoutofthe
box,andwillnotprovideadequateshieldingforallenvironments.Casegroundmustbeusedtoprovidefull
EMIprotection,andensurethecableshieldisgroundedononlyoneendofthecable.
CaseGrounding
ThecaseiselectricallyconnectedtoPin5oftheDB‐15connector.ThePin5shouldbeelectricallyconnectedtothe
user’scableshield,especiallyifthechassisdoesnotmakegoodgroundcontact.Thecaseshouldbeboltedtoagood
conductingsurfacethatisgrounded.