u-blox ANTARIS 4 - Page 86

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your position is our focus
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Figure 72: NMEA Protocol Framing
NMEA Parser
TheNMEAspecificationisfairlyopenandallowsminorvariationsintheimplementation(e.g.numberofposition
afterdecimalpoint,etc.)butitalwaysrequestscommasbetweenasaseparatorbetweenNMEAdatafields.One
is
leto
thehandlethevalidflagscorrectly.
Dataareonlyvalidifthevalidflagisset
tovalid.Ifit’ssettoinvalid,theNMEAparsershouldrejectdataoutput
bythereceiver.Bynomeansshoulditforwardittotheapplication.
NMEA messages supported by the ANTARIS
®
4 GPS Technology
TheANTARIS
®
4GPSTechnologysupportsNMEA-0183,version2.3.ThisisupwardcompatiblewithNMEA-0183
version3.0.TheNMEAprotocoldoesnottakeadvantageofallthefeaturesoftheANTARIS
®
4GPSTechnology,
duetobandwidthlimitationsoftheASCII-protocol.
• StandardNMEA
• DTM-DatumReference
• GBS-GNSSSatelliteFaultDetection
• GGA-Globalpositioningsystemfixdata
• GLL-Geographicposition-latitude/longitude
activesatellites
• GSV-GNSSsatellitesinview
mumspecificGNSSdata
andgroundspeed
TXT–Textmessages
should therefore write a parser that searches for commas and extractseverything between two commas.
Th
way,theparseris independentofthenumberofdigitsfortheindividualmessage fields.Itwillevenbeab
handleemptyfields",,".Besidethecommas,agoodparsershouldbeable
• GSA-GNSSDOPand
• RMC-Recommendedmini
• VTG-Courseoverground
• GRS-GNSSrangeresiduals
• GST-GNSSpseudorangeerrorstatistics
•
• ZDA-Timeanddate
GPSModules-SystemIntegrationManual(SIM)(incl.ReferenceDesign) ReceiverDescription
GPS.G4-MS4-05007-A1
  Page 86