Replies to This Discussion

Permalink Reply by Vernon Barry on June 30, 2012 at 8:21am

Just going on a limb here but the 433mhz 3DR radios had a problem with USB noise, so it's not entirely impossible that noise from your particular computer is blocking the GPS signal and that would go a long way in the explanation since this seems to occur anytime USB is plugged in. Try one of those ferrite beads on the USB cable or maybe a different machine?

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Permalink Reply by Michael Pursifull on June 30, 2012 at 9:33am

It's RF Interfearance, most likely from your esc, but maybe from a telemetry radio or rx. Move these things and any cables a few inches farther from your gps antenna and test until you figure out which one.

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Permalink Reply by Mike Mac on June 30, 2012 at 9:39am

First you should clear the memory and flash the firmware again. It could have become corrupted. If you have telemetry or any other optional sensors you should disconnect that until you get the GPS working correctly.

　

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Permalink Reply by Michael Müller on July 1, 2012 at 7:27am

Thank you all very much for your suggestions. But last night I found what the problem is but without a solution.

The problem is a defective out1-Pin. As soon as I connect a S-cable from any ESC to pin 1, no GPS-Lock can be established. When I additionally connect the USB, I got GPS-Lock. This cenario is reproducable, I checked it a dozen times. Of course I reflashed firmware with prior erase. And of course I cut the red and black ESC-cables. Powering is via UBEC on the out rail with JP1 set.

Anything else works great, flys perfect stable, but no GPS when pin out1 is connected.

What options do I have now?
- send it back and get a new one ( it´s only two weeks old), than I´m maybe without a copter for weeks, I´m from Germany
- solder pin out1 new (do I loose warrenty than?)
- modify firmware to get the signals from pin1 to pin7 (I fly a hexa+) But than I can never fly a octo with this APM

Any other suggestions? What can I do now?

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Permalink Reply by Andre S on July 1, 2012 at 11:30am

Are you absolutely sure that the problem is specific to pin 1? For example, do you get a GPS lock when your ESC BEC is connected to any other pin?

I think your problem sounds more like a noisy power supply (the BEC integrated in your ESC). I had a similar problem (as a few other people in the forum) and since I power the APM, GPS, etc. from a separate supply these have disappeared. Just an idea..

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Permalink Reply by Michael Müller on July 1, 2012 at 11:50am

To prevent such problems I use this UBEC.

(see my next post)

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Permalink Reply by Michael Müller on July 1, 2012 at 11:32am

This GPS-Lock-Problem drives me crazy.

Today I tested it again and placed the APM 4" outside the middle of the copter and now I get GPS-Lock even with out1 pin connected. I have nothing connected but power from UBEC on out-rail and the white cable from ESC 1.  Placing it in the middle, over the power distribution board, Iget no GPS-Lock.

So I think Mike is right, it is an interfearence.

What con I do now? Can I shield it in any way?

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Permalink Reply by Remi on July 1, 2012 at 1:38pm

Hi,

I had exactly the same problem as yours : GPS lock when the APM 2 is USB powered and no lock when it is powered by the ESC. I had some results with an external ubec (the same as yours) + putting my receiver on one of my quad's arms + putting 1 ferrite coil on the cable powering my rx from the APM. It's still not optimal : sometimes I get a lock in 1 or 2 minutes, sometimes in 10 minutes and sometimes I don't get any lock. I ordered some thin coaxial cable and I will try to make every cable shielded + a shield below the APM with some coppered epoxy. I hope it will help...

If I knew the GPS is so sentitive I'd certainly ordered my APM with an external GPS...

Best Regards,

Remi

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Permalink Reply by Michael Müller on July 1, 2012 at 11:59pm

In my case there were interferences with the power supply board directly under the APM. Maybe shielding with a CFK-Plate is also the solution for you.

And yes, a GPS which is not so sensitive would be great.

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Permalink Reply by Remi on July 2, 2012 at 12:08am

How thick is your CFK plate ? I'll try with a plain printed circuit board I already have first.

Thanks for your answer.

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Permalink Reply by Michael Müller on July 2, 2012 at 12:32am

My CFK-Plate is 2 mm thick and on all 4 sides 2" larger than the APM. Maybe it also works with the circuit board. Good luck.

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Permalink Reply by Michael Müller on July 1, 2012 at 1:36pm

SOLVED

I placed a CFK-Plate between power distribution board and the APM. Now I Have GPS-Lock after 2-3 min.

Thank you very much for your help.

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