Fixed: NMEA 0183 Heading from two sentences, one wrong

[xentac]

I'm not sure which aspects are relevant, so I'm going to be overly verbose.

I have an Airmar DST810 hooked into an NMEA 2000 network, being read by a Vesper Cortex. I'm using openplotter to read the published NMEA 0183 data through signalk.

I have noticed that navigation.headingMagnetic mostly publishes the right value, but then occasionally jumps to 0. navigation.headingTrue and navigation.headingCompass don't exhibit the same issue.

Data browser tells me that navigation.headingMagnetic comes from the HDG sentence when correct and the VHW sentence when 0.

Example HDG sentence: 1701565202730;N;$AIHDG,1.9,,,7.9,E*2C
Example VHW sentence: 1701565203169;N;$AIVHW,,T,0.0,M,0.0,N,,K*5D

As far as I can tell, it's because of the 0.0,M in the VHW sentence. The reason it doesn't have the same problem with headingTrue is because the parameter is ,T.

If I exclude the VHW sentence, I lose STW information entirely, which I don't want to do. I think what I want to do is exclude magnetic heading from VHW but I have no idea how to do that.

Suggestions?

[sbender9]

Use "Source Priorities" under Server -> Data Connections.

[xentac]

I tried that, but both sentences come from Cortex.AI. I don't think I have an option to say prioritize one sentence over another.

…

On Sat, Dec 9, 2023, 5:53 PM Scott Bender ***@***.***> wrote: Use "Source Priorities" under Server -> Data Connections. — Reply to this email directly, view it on GitHub <#87 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAAAODKKGBDUNSLGTLFUSI3YIUBY5AVCNFSM6AAAAABAOCCUKKVHI2DSMVQWIX3LMV43SRDJONRXK43TNFXW4Q3PNVWWK3TUHM3TQMBZGU2DC> . You are receiving this because you authored the thread.Message ID: ***@***.***>

[tkurki]

You can filter incoming data with the Node-RED plugin, this flow will block navigation.headingMagnetic from sentence VHW:

https://gist.github.com/tkurki/5fce1559c9e598df6029f8c95b1a3fc2

Option to include sentence in NMEA0183 data $source string value would be useful in this case, then you could use source priorities.

[xentac]

That did it. Thanks!