OpenCPN Magnetic Variation Reversed?

[Hakan]

Originally Posted by rooiedirk

Nmea version 2.3 is from march 1998 Would we break something by adding an extra field?

I don't think so. Who would search a sentence from the end? I could very well test a change on my dated AP.
But...
The "new" FAA mode field is valid both for RMB and RMC. Both ought to be change if any.
Could you make a test branch and I'd try it on board? Or I may try to change but it will take some more time.

[Hakan]

I recognized RMC is already adapted for version 2.3 so what's left is similar changes for RMB?

[kumado77]

Hello,
nice job on the magnetic field, however:
The upper line is made from the RMC phrase. Left = SOG (field 7 in RMC) and right is COG (field 8 in RMC) This did work fine with the added magnetic varaiation.


The lower line is causing the problems, where to steer:
It is made by the RMB phrase, (left: field 10 in BMR, right: field 11 in RMB) which either does not appear at all or disappears.

[kumado77]

Hi,
the $ECRMC,211754,A,4117.178,S,17400.463,E,-1.#IO,0.000,200618,22.200,E

and nand(ind)
are caused by an overflow in your reading buffer at the listener.
There is no handshake between opencpn and listener. Once the buffer flows over, it stops to listen. Unfortunately opencpn doesn't listen to this "cry of shutting up" and keeps on talking. The effect is rubbish.
This proboem is known, but the developers consider it not worth to work on : What i do not agree with.

[bdbcat]

Hello...
There is at two errors in OCPN regarding synthesized sentences for autopilot.

re:
$ECRMC,211754,A,4117.178,S,17400.463,E,-1.#IO,0.000,200618,22.200,E

The error in synthesized ECRMC is not due to any buffer overflow. It is a simple coding error in OpenCPN. If SOG is undefined, OCPN does not properly detect this, and in error adds a (NAN) to the sentence. Downstream receivers cannot decode this properly (probably the # symbol causes them trouble).

Hakan showed a viable solution in the code here:
http://www.cruisersforum.com/forums/...ml#post2656608

It will be fixed for the next release. @Hakan, I'll take a PR on this.

There is an additional problem. Some NMEA receivers require the trailing FAA 'A' character to parse RMB correctly. This fix is already in place for RMC. It is a simple fix for RMB, as well. We will do this for the next release.

Maybe this is the root cause of the reported trouble with "lost" sentences with some receivers in some configurations.

Sorry for the trouble.
Dave

[Hakan]

@kumado77... (Or anyone else as well)

I've a Windows installer for O version 4.99.0 where the NMEA version 2.3 FAA mode fields are added to RMB and RMC sentences sent to AP. I've tested on my dated Simrad AP without any troubles, as expected.
It would be great if you could test on your system to verify it solves your problem.

The fixes includes:

1. Avoid "NAN" in SOG/COG to AP. (When no GPS is there!?)
2. Understand also incoming FAA mode indicator for RMB (NMEA version 2.3)
   
3. Include the FAA mode indicator in $ECRMB and $ECRMC to AP

Please PM me for a download link.
Thanks
Håkan

[gchead]

I have now installed OpenCPN V. 4.99.0 and am very happy to report it works perfectly and has resolved the problem with the NASA Clipper GPS Repeater needing NMEA Version 2.3 and above to display bearings to steer to.

Thank you, thank you!!

I have tested while stationary in the marina (for a couple of hours) and I don't see any reason why there will be any problems while under way.

I did note that the NMEAConverter Plugin is NOT compatible with this version. Not a problem for me as I don't need it now

[Hakan]

gchead...
Nice to hear and thanks for the report.
For info is the O version you have got not present Git master but I hope the patch is soon merged.
Plugins: Yes, most not inbound plugins have to be updated before they can be used in O ver. 4.99.0.
Håkan

[gchead]

Originally Posted by Hakan

gchead...
Nice to hear and thanks for the report.
For info is the O version you have got not present Git master but I hope the patch is soon merged.
Plugins: Yes, most not inbound plugins have to be updated before they can be used in O ver. 4.99.0.
Håkan

Did this patch make it into the new OpenCPN Version 4.8.8 released today?

(No mention of it in the release notes)

[gchead]

I have written a summary of my experiences interfacing the NASA GPS Repeater with OpenCPN on my Halo Logbook:
https://halologbook.wordpress.com/20...wifi-aug-2018/
The system works very well for me and is a great solution for my coastal navigation adventures in New Zealand.