Help - Possible 'Ships Position' Bug

[sy_gilana]

Hi, I don't know if this is off subject. I seem to have stumbled across a bug.
Using 1.3.6, Win Xp sp2. (also running the beta, same)
If my gps is connected to the USB via Serial adapter, running sentences from my Raymarine equipment, at 38400,n,8,1 through an AIS 161 as MUX, and I select "Move Boat Here" via context menu, the boat moves to the indicated position with live NMEA sentences coming in, but refuses to snap back to the real GPS position, and will make relative movements according to GPS input.
If I connect a Navibe GPS directly to the usb port emulating a RS232 port, and select "Move Boat Here" the boat snaps back to the actual GPS position so fast that it never appears in the "drop" position.
The differences between the GPS inputs are:
1 Baud rate
2 Sentence prefix, in the case of Ray* the prefix is "II" (Integrated Instrumentation) and the Navibe is "GP" Garmin Protocol.

I suspect the update position subroutine is ignoring the II.

I am working around the bug, but any comment is welcome...

West Palm Beach huh? Loved it there just south of the Blue Heroin Bridge.

[bdbcat]

sy_gilana

Thanks for the report.

Don't know what you mean by
...."will make relative movements according to GPS input"....

Have you looked at the data stream coming from AIS Mux? Can you report that here in detail?

Thanks
Dave

[sy_gilana]

Hello Dave
Here are 3 cycles from the MUX
!AIVDM,1,1,,B,15Blh>00370DNHfF>Aurp8hF00S7,0*75
$IIHDM,040.,M
$IIHDT,038.,T
$IIVTG,000.,T,002.,M,00.0,N,,K
$IIGLL,3932.39,N,00320.12,E,,A
$IIHDG,040.,,,02.,W
$IIBWC,,,,,,,T,,M,,N,
!AIVDM,1,1,,B,15DnAB00300FhOpFvoETW3dF05:H,0*55
$IIHDM,040.,M
$IIHDT,038.,T
$IIVTG,000.,T,002.,M,00.0,N,,K
$IIGLL,3932.39,N,00320.12,E,,A
$IIHDG,041.,,,02.,W
$IIBWC,,,,,,,T,,M,,N,
!AIVDM,1,1,,B,15QNSh002qP=UNPFMcK;UI>H00S1,0*70

And here are three cycles from the Navibe:

$GPGSA,A,3,20,04,13,23,,,,,,,,,6.6,4.2,5.1*35
$GPRMC,094306.000,A,3932.3921,N,00320.1359,E,0.00, ,290410,,,A*7B
$GPGGA,094307.000,3932.3921,N,00320.1359,E,1,04,4. 2,6.2,M,50.9,M,,0000*52
$GPGSA,A,3,20,04,13,23,,,,,,,,,6.6,4.2,5.1*35
$GPRMC,094307.000,A,3932.3921,N,00320.1359,E,0.00, ,290410,,,A*7A
$GPGGA,094308.000,3932.3921,N,00320.1359,E,1,04,4. 2,6.2,M,50.9,M,,0000*5D
$GPGSA,A,3,20,04,13,23,,,,,,,,,6.6,4.2,5.1*35
$GPRMC,094308.000,A,3932.3921,N,00320.1359,E,0.00, ,290410,,,A*75
$GPGGA,094309.000,3932.3921,N,00320.1359,E,1,04,4. 2,6.2,M,50.9,M,,0000*5C

OK to explain what I mean by "Will make relative movements"
If I am sailing course 090 spd 5.0 and position x:y = gps input, I right click and "move boat here" and displace by x:y = 5:5 for example (5 miles NE), the boat icon moves to the new location and continues 090 @ 5.0, it seems to SUM the manual input to the GPS input almost like a "Position Correction"

Hope I have been able to explain it better...

Regards
Mike.

[sy_gilana]

Oh,something else I just noticed, the boat icon is a different color too. With Ray* its grey, but with Garmin/Navibe its a green or red if I remember...

[bdbcat]

sy_gilana...

OK, that a real bug! Congratulations, I think!

The bug occurs when handling xxGLL sentences with no checksum.
Will be fixed in next Beta. Meanwhile, can you persuade the Ray hardware to send checksums on NMEA data? That should be a temporary workaround.

Thanks
Dave

[sy_gilana]

Yup it would appear that the SR161 is stripping the checksums *hh
There are a whole host of features that will not work without checksums, including the flashing next waypoint on active route.
Will play with SR161 to see if I can program the thing to checksum, AIS is more important than the problem.

Where are you in West Palm? have a friend there who has a dock out the back of his house.

[sy_gilana]

It is not the SR 161 that is stripping checksums, Apologies to Milltech Marine and Smart. The Ray* BLACK autopilot course computer type 3 does not issue checksums.
My L755 plotter/sounder does, but does not transmit HDM and HDT which I like.
I connected the L755 to the AIS today and NONE of the NMEA sentences are being sent through the SR161, on the phone to Milltech shortly to discuss.

[sy_gilana]

Had a chat with Mike from Milltech marine, good guy! It seems that I am not the only person who is seeing this problem. As OpenCPN becomes more popular, users of the SR 161 will find the same problem. Subject to correction, this is the situation.
OpenCPN needs CRC, and the SR161 does not like them, and will not MUX them out.
My workaround will be to go off and buy a second Serial to USB converter and get my AIS on Com:A and GPS on Com:B, I will still not have HDM and HDT , but it is a workaround...
Will keep you posted.
Mike on Gilana