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Topic: Electromagnetic interference? (Read 4796 times) previous topic - next topic

Wawa

#30
Aug 24, 2016, 01:24 am Last Edit: Aug 24, 2016, 01:36 am by Wawa
I think OP is using two switching/buck supply modules with USB socket and voltage display to drop the voltage of four AA batteries to 5volt. They would switch/regulate when batteries are 6volt, but just conduct (silent) when battery voltage has dropped below ~5.5volt.
Leo..

allanhurst

Still think it's mostly a radiated interference problem. The fact that it all works lying on the bench
but not when assembled tightly into a flight box impliesthe  interference generated by the camera only becomes significant when very close to the GPS receiver.

So put the camera in a seperate faraday-shielded enclosure to reduce radiated interference as I suggested, and use ferrite beads on the leads to it to reduce conducted interference.
  I suddest you only leave the lens unsheilded, but even there you could put earthed wire mesh over it. The focus of the lens will be at infinity, and a bit of mesh over it will not appear on the image - try it.

regards

Allan..

ps I spent years in the RF business, and solving EMI problems like this was often necessary.

TomGeorge

Hi,
Wrap the camera in Aluminium Foil.

Tom.... :)
Everything runs on smoke, let the smoke out, it stops running....

exceleronsports

Thanks everyone for the responses.   As a matter of wrap up and to help anyone that may come across this in the future, the issue was indeed interference from the cameras themselves.  A previous reply mentioned this possibility with GoPro.  My cameras aren't actual GoPros, but it still happens with me.  It's easier to call them GoPros, but they are actually Lightdow action cameras:

https://www.amazon.com/Lightdow-LD4000-Sports-Action-Camera/dp/B00X9Y2NFY/ref=sr_1_2?ie=UTF8&qid=1472134137&sr=8-2&keywords=lightdow

I would not have expected this since the cameras do not have any Wi-Fi or Bluetooth capabilities so I didn't expect them to be emitting any interference, but they indeed were.  As soon as I moved the cameras in close to the Arduino, all sorts of crazy things started happening.  The GPS would lose signal, the status LEDs would stop working and the Arduino would erratically stop processing the main loop.  As soon as I moved the cameras away - we're talking only like 6 or 8 inches away (15-20cm) - everything would resume normally.

In any case, I wrapped the entire camera, except the lenses, in tin foil and that resolved the issue.  I no longer saw any interference occurring.  Thanks again for the input!

arssant

#34
Aug 25, 2016, 04:45 pm Last Edit: Aug 25, 2016, 05:51 pm by arssant
In any case, I wrapped the entire camera, except the lenses, in tin foil and that resolved the issue.  I no longer saw any interference occurring.  Thanks again for the input!
Nice, glad to hear that.

Another concern, with wrapping the cam with metallic foil, take care about heat. When operating  continuously some cams could generate "some" heat, and the wrapping will deny a good thermal dissipation. Check that before the final lunch.

exceleronsports

Agreed!  That is actually one of my major concerns with the new solution.  It does get quite cold in the upper atmosphere, but at the moment our payload is so well insulated that it has been staying quite warm in the payload box (15° C) even when it's very cold outside the box (-50° C).  We're likely going to need to adjust our design to let the cold air in a bit.

TomGeorge

Hi,
Quote
Another concern, with wrapping the cam with metallic foil, take care about heat. When operating  continuously some cams could generate "some" heat, and the wrapping will deny a good thermal dissipation. Check that before the final lunch.
Paint the foil black, if its inside the payload area it will act as a Black Body Radiator.


Tom.... :)
Everything runs on smoke, let the smoke out, it stops running....

Wawa

You could shield one thing (the camera) or the other (whatever is interfering with it).
Whatever is easiest.
Leo..

allanhurst

If you shield the GPS receiver, it won't work!

regards

Allan.

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