radar_pi question

[77Californian]

Hi all,

I'm using the current releases of opencpn for windows and the radar_pi plugin and have a Simrad 4G radar. I only have a few hours of use with the set up. So far ut has worked beautifully (Many thanks to the contributors)

One question I have: Periodically, each of the radar images (virtual A, virtual B, Overlay) disappears and starts over in the sweep. Sometimes at the same time, sometimes independently. The time is a little variable, but about every few to several seconds. A and B do it independently, it happens to the overlay and associated individual window at the same time. It happens over both hard wired and wireless connections with no other data along the path.

Is this typical? Or is something up?

Thanks!

[Hakan]

77Califonian...
No it's not typical. We've been running for long time periods at the tests. During development of the plugin we though saw something similar for the overlay only but not in the resent version 5.0.x and it was for certain video cards only. To be sure check an updated version of the plugin. https://github.com/opencpn-radar-pi/radar_pi/releases

But I've seen a similar effect when the position or heading updates are delayed. In that case the radar info window used to be shown at the same time. If that is the case you can use the NMEA debug window (Options->Connections) to check if the GPS/compass data is thoroughly updated without several seconds in between.
Håkan

[77Californian]

Wow! That was the most amazing remote debugging, ever!

It was apparently getting confused between the heading from the radar and the heading from my autopilot's EV-1 sensor core. They must occasionally differ by just enough, or something.

I checked the "Ignore radar heading" box in radar display preferences -- and problem solved.

THANKS SO MUCH!

[Hakan]

So you detected that two headings was received and made the correct conclusion.
Well done. Indeed!

[77Californian]

Hi Hakan,

Whelp, I'll admit -- once you taught me that the errant behavior has previously been observed to occur when the plugin is fed conflicting/inconsistent heading and/or position data -- checking the box labeled (approximately), "Eliminate one of the two conflicting inputs" was a breeze. :-)

(For anyone who runs into this post while debugging later, I was able to, as Hakan suggested, capture the NMEA input, filter it down, and see the two heading sources there. So, that was a great debugging step).

Thanks again!

[Douwe Fokkema]

Originally Posted by 77Californian

Hi all,

disappears and starts over in the sweep.

Can you explain what you see more precisely? What means "starts over in the sweep"?


You should have a nice and continuous radar image. When heading or position drop away the radar windows should continue if in "head up" view.


Douwe Fokkema

[77Californian]

Hi Douwe,

Thanks for offering to help!

Just to be clear, the problem is now fixed. It seems like what was happening is that the heading data coming from my autopilot's EV1 soensor core and the heading data coming from the radar were different enough, at least occasionally, to cause the problem. Checking the "Ignore radar heading" box in the radar setup, which I assume leaves it relying only on the Autopilot's heading data, seems to have fixed the problem.

Having said that, in case you are curious or just want it documented for someone else, let me answer your question about the symptoms. As you suggested, now that things are working correctly, I have a nice continuous radar image, with a new spoke replacing an old one as the radar scans round-and-round.

But, when I was experiencing the problem, periodically the radar image would completely disappear and the scan would continue with a spoke several degrees ahead (clockwise) of where I would have expected it. So, I was seeing a continuous scan with periodic episodes of clear-and-skip-ahead.