[gpsd-users] GPSd NMEA only parsing GGA, not VTG

[Thomas Peel]

Hello,

I'm requesting some help as I've been struggling with the following issue for 
several days without finding any explanation to what's happening.

I would like to use GPSd on a research vessel to make ship's position available 
to everyone onboard. Therefore, I need to parse generic NMEA GGA and VTG 
sentences. Here is what the sentences look like from the serial port GPSd is 
listening to :

$GPGGA,030013.00,1401.83717,N,13008.84236,W,1,06,01.1,000.000,M,0.0,M,0.0,0000*58
$GPVTG,126.48,T,069.57,M,000.05,N,000.10,K,D*26

Unfortunately only GGA is parsed. VTG seems to be ignored, though the syntax 
looks correct. Here is a dump of GPSd running with debug level 8 :

gpsd:IO: <= GPS: 
$GPGGA,030401.00,1401.83545,N,13008.84126,W,1,06,01.1,000.000,M,0.0,M,0.0,0000*58
gpsd:DATA: GPGGA: registers fractional time 30401.00
gpsd:WARN: can't use GGA time until after ZDA or RMC has supplied a year.
gpsd:DATA: GGA: hhmmss=030401.00 lat=14.03 lon=-130.15 alt=0.00 mode=3 status=1
gpsd:PROG: GPGGA sentence timestamped 30401.00.
gpsd:PROG: GPGGA starts a reporting cycle.
gpsd:PROG: GPGGA ends a reporting cycle.
gpsd:DATA: packet from /dev/ttyS0 with 
{ONLINE|LATLON|ALTITUDE|STATUS|MODE|PACKET|CLEAR|REPORT}
gpsd:IO: <= GPS: $GPVTG,209.25,T,070.17,M,000.10,N,000.18,K,D*23
gpsd:DATA: packet from /dev/ttyS0 with {ONLINE|PACKET}

Testing other sentences reports that GGA, RMC and ZDA only are parsed. All the 
other sentences are ignored like VTG.

Could you please give me some clues on where this problem could come from?
Many thanks in advance,

Thomas Peel

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