Quadcopter NAZA GPS <> GoPro 2 interference issue solved!
I finally solved it by building a thin gopro housing out of coroplast and lining it with copper foil. I've tried everything else, copper plate under gps, alum foil under gps, toroids on gps ant wire, etc.. nothing worked except for this.
I think the reason why this is not a problem everyone notices is that it's not entirely evident when flying in wide open areas with a clear view of the sky. The problem shows up when you have a marginal GPS signal, trees, clouds, or both when all of a sudden the gopro noise effects the lock. This was my situation. The thin coroplast case + copper foil is very lightweight and not bulky. Happy with it as it also provides some protection for the bare gopro as well.
NOTE: Copper and CA glue must have some type of reaction because CA bonds the copper foil to the coroplast amazingly well. It heats up quite a bit too
What I tried:
I tried a very large toroid on the GPS line and could not get any measurable improvement. I tried copper plate, and aluminum foil on both the back of the gopro and under the GPS disc and that seemed to help a tiny bit but by no means a solution. I picked up some copper foil from the local Hobby Lobby and found I needed to cover the back and top of the gopro at a minimum. - Major difference! This solution greatly reduced the RFI coming off the gopro but doesn't eliminate it as I can still hold the gopro within an inch or two of the gps and cause problems.