Maybe I'm a little clueless on how radar works, but how would something that is lower than a car's height be mistaken for something as distant as a overhead sign?

I would assume the forward radar isn't capable of seeing anything past a foot or two off the ground.

I suppose I don't really know, but that was Elon's answer to "why didn't the radar see it?"

tweet: "Radar tunes out what looks like an overhead road sign to avoid false braking events"

That's what puzzles me. I don't get how overhead road signs can be a problem, and it couldn't detect something at car height. Its just really odd.