I got a single wire UART bus spanning dozens of meters, and things on it tend to glitch and lock up a few times a week.
I've tried adding clamp and TVS diodes and series resistors, to little effect.
Eventually i sat there staring at a scope for a few hours, and was able to capture several bursts at 2.5MHz, about 4 times an hour. They vary in duration and intensity, but are fairly consistent in frequency.
What is it, where can it be coming from and how to protect from it?
I suspect weather might have something to do with it, since it's much rarer in the winter than in the summer, but i don't see where the frequency comes from.
I'm also near an airport with planes flying over, but the bursts are there even at night when no one is flying and don't seem to coincide with the planes in any obvious way.
EDIT: Fixed images




