WiFi signals can measure heart rate

Hey, I heard about how utility pole inspecting helicopters are able to tell the good/rotten state of wooden telephone poles by the reverb pattern of sound waves coming off the poles from the rotors -- it seems to me the whole field of non-invasive sensing (and using existing/ambient emission sources) is getting pretty impressive.

What kind of helicopter of what size are we talking about here that can actually get close to a utility pole with wires going across?

I live near a helicopter factory and when the spinning towers are in use, you hear all sorts of auditory patterns as you move around the town. When they are test flying - similar and the Police have one and there is an air ambulance too. My Dad's other staff car in the '80s was a Gazelle and in the '70s he whizzed around in a Sioux. I've seen and heard a lot of helos!

I have absolutely no doubt that with some funky signal processing you can do all sorts of things.

And here I thought living behind a few garages that rev engines all day long was disturbing