Decoding NMEA sentences

BlueChip

BlueChip

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Can anyone identify which of the following NMEA sentences (abstracted from a much larger file) show the depth data?

$GPBOD T M *47
$GPGGA 105216 N 107.028 W 1 7 1.8 5 M 48.3 M *57
$GPGLL 5047.461 N 107.029 W 221614 A*32
$GPGSA A 3 9 15 18 26 27 28 4.5 2.3 3.9*37
$GPGSV 2 1 8 8 11 70 0 9 41 263 0 15 83 238 0 17 18 104 00*7A
$GPRMB A 8.56 L 3 5042.05 N 136.52 W 19.5 254 V*09
$GPRMB A 8.56 L 3 5042.05 N 136.52 W 19.5 254 V*09
$GPRMC 221614 A 5047.461 N 107.029 W 0 111.1 290810 4.2 W*78
$GPRTE 1 1 c 0*07
$PGRME 37.3 M 30.2 M 47.9 M*12
$PGRMZ 9 f 2*13
 
I did some of this once upon a time. I've forgotten all of it.

THis:

http://www.windmill.co.uk/nmea.html

Suggests you are looking for an SD prefix (for sounder info) followed by DBT (Depth Below transducer).

Do you have anything like that in your larger file?
 
Strange, definitley no data with that header. I'm taking the data from a Raymarine Seatalk/NMEA mux and I know depth is there because my ICS Navtex repeater shows it.
Wonder what is going on?
 
Didn't quite follow how you were routing your info from SeaTalk and displaying it back again - but I have had issues where some of the Raymarine to NMEA converters (e.g. from the autopilot) do not translate all the sentences available on seatalk to NMEA.

Check the detailed spec of the converter you are using - somewhere they normally list sentences output.

P.S. I think the first 2 letters of the NMEA sentence can be manufacturer specific - its the last 3 characters of the 5 letter block that you want to focus on
 
Seatalk data from Raymarine instruments and NMEA data from GPS are combined using a Seatalk multiplexer and all data are output in NMEA strings.
I think I must be picking up the NMEA GPS input to the multiplexer rather than the output.
The NMEA input woouldnt contain the depth data.
Thats the only explanation I can see. I'll check.
 
PembrokeshirePromise said:
Didn't quite follow how you were routing your info from SeaTalk and displaying it back again - but I have had issues where some of the Raymarine to NMEA converters (e.g. from the autopilot) do not translate all the sentences available on seatalk to NMEA.

Check the detailed spec of the converter you are using - somewhere they normally list sentences output.

P.S. I think the first 2 letters of the NMEA sentence can be manufacturer specific - its the last 3 characters of the 5 letter block that you want to focus on
Click to expand...

PP, the link you posted does suggest that. There are examples for Garmin and for Magellan. I think you are correct. The data above does look standard, though, with the GP prefix.

I'm not familiar with Seatalk, although I think my autopilot speaks it. Haven't yet managed to get that to talk to my Lowrance chart plotter however.......
 
Here are examples of the data your looking for which I captured from my echo sounder for the teamsurv depth logging project.

$SDDPT,27.0,-1.3,*61
$SDDBT,88.6,f,27.0,M,14.8,F*38
$SDDPT,33.7,-1.3,*63
$SDDBT,111.7,f,34.0,M,18.6,F*08
 
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