I've been surprised that no vendor has put a motion/vibration sensor in their keyfobs. I know they're pretty power constrained in keyfobs, but it seems like a

I've been surprised that no vendor has put a motion/vibration sensor in their keyfobs. I know they're pretty power constrained in keyfobs, but it seems like a pretty sensible protection to require the fob to be not sitting still on a table to do a proximity-only unlock.