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Problems with intermittent bad GPS data
#1
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Hi all,
A few months ago, I posted here about having problems with getting intermittent bad GPS strings from OP. Every so often, I'd get a LAT that was 00.000, which would cause my track to plot a line down to the equator and back. I turned off pretty much all of my SignalK to NMEA tools, and it seemed to rectify the problem. I also logged the data from my GPS, and confirmed that it was consistently giving me good data.

A few days ago, I decided to try the new beta version of OpenCPN, and switched to a SignalK connection to OpenPlotter. I'm at home now, but I leave it all running to keep track of AIS in the nearby marinas, and to see if the problem I described above is going to come back. It did come back. Here's an image of the track from my stationary system:

[Image: opencpn.jpg]
I zoomed out so you can see where the tracks go. The erroneous entries show in the track log like this:

Code:
     <trkpt lat="20.705389500" lon="-105.298959167">
       <time>2020-05-18T22:33:11Z</time>
     </trkpt>
     <trkpt lat="0.000000000" lon="0.000000000">
       <time>2020-05-18T22:33:17Z</time>
     </trkpt>
     <trkpt lat="20.705337000" lon="-105.298930500">
       <time>2020-05-18T22:33:19Z</time>
     </trkpt>

Here's another one:
Code:
     <trkpt lat="20.705309667" lon="-105.298937167">
       <time>2020-05-18T22:35:27Z</time>
     </trkpt>
     <trkpt lat="-89.906772203" lon="-89.906772203">
       <time>2020-05-18T22:35:31Z</time>
     </trkpt>
     <trkpt lat="20.705326167" lon="-105.298942667">
       <time>2020-05-18T22:35:34Z</time>
     </trkpt>

I've turned off tracking and cleared tracks several times, and after about a day I get this again. 

I can switch back to NMEA for OpenPlotter, and perhaps that would solve the problem for the moment, but I'm very interested in moving to SignalK as much as possible. This is becoming a barrier to me doing that. Since I had this problem in the past with OpenCPN 5.0, I'm reluctant to submit this as a bug to the OpenCPN team, as I think this may be a case of bad SignalK data coming from OP.

Does anyone have any ideas on how I might continue to troubleshoot this?

TIA

Andy
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Problems with intermittent bad GPS data - by abarrow - 2020-05-19, 02:27 PM

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