Howdy... I'm back in the air this week after QC replaced my fried MX20. They also want me to send back ALL my motors so they can see if the bearings are fried Still, I needed to test the setup today, so I went for a few short flights... In this particular flight, I had a GPS fix with 9 sats. I took off and engaged GPS pos hold. After a few seconds, the C8 started veering to the left, and then back to the right. My MX20 beeped, and I looked down to see GPS Lost! 0 Sats. A moment later, they were back. Then they were gone again. I switched off GPS hold, and flew for another minute. Then I landed... I checked all the connections, and saw nothing wrong. Flew again, and there was no issue. GPS locked on and held all flight. What I don't undertand is this GPX file... It reports no errors, and says the GPS was locked on the whole time.... What gives? Best, Ben
Ben depending on the time of day there was some solar activity today. Anytime it gets into the Yellow zone GPS is unreliable on our copters. That might do it even with 9-10 sats showing up. This would have been about 1500Z. Also while you had a good number of satellites their effectiveness is also predicated on them being well positioned for the 3D fix. Take a look at http://satpredictor.navcomtech.com/ and you can see how many SATs were high in the sky giving you the fix at the time and location of your flight.
So, to separate the points: 1) You mention that during the 'yellow' zone there could be unreliability, but my flight wasn't in the zone. Seem like a red herring??? 2) I attached the GPX file. There were no errors logged, and the file seems to indicate a constant GPS lock. Yet, the MX20 indicated 'GPS LOST' several times, and 0 sats tracked. And during those moments the heli veered way off it's position hold. Thoughts? Best, Ben
Remember that the GPX file is only written once a second. If something happens during the gaps between the one second interval it will not be recorded in the GPX file. Granted it's a bit suspicious that you didn't see the problem in the GPX file -- one would have thought that you'd see at least one flag set, but if the dropout was really transitory, that might explain things.... Andy
The other possibility is a problem with the telemetry download from the MK stack to the Graupner. Check your connections on the GR24. Do you have the voice prompts turned on? Another possibility is a spotty connection on one of the ribbon cables or something. Lastly, were you flying in an area with lots of RF interference or anything like that? Power lines? Cell towers? Nuclear power plants?
Howdy... If it were the telemetry download, I would suspect I would lose all the info, such as battery and altitude info. Those were strong... Just the GPS signal was lost... Ribbon cable could be an issue. I flew 2 more flights today, and no further issues. I have hot glue on my ribbon cables, and they look ok to me, but who knows... Any other thoughts before I write this off to an 'act of God? Best, Ben
Yeah, Ben....don't write it off. The equipment is telegraphing something to you. So listen to it carefully....like be very carefully to check you have a GPS lock before you start the motors, and look for the same error repeating itself. Nothing these birds (and their avionics) do is ignorable, I'm afraid. It all means something (even if that something means, "Don't worry, it's ok!"). Andy.