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Comment by bpowah | Hacker News Reader

So my WiFi should easily be able to detect if my (all metal) garage door is open or closed? I would like this. I run dd-wrt. Is there an all-software solution to this? Or does this research rely on fairly specialized hardware? (sorry, didn't have time to read the whole article)

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Probably, the first thing I thought about when I saw this was WiSee ("Whole-home gesture recognition using wireless signals"), which is also from UW: http://wisee.cs.washington.edu/

The research relies on special hardware, but you don't. I wouldn't be surprised if you could tell whether your door was open or not just from signal strengths of external wifi signals.

On reading the paper rather than the article: it's even simpler than I thought. No custom hardware necessary.

It requires a custom 3D-printed "device" on the door, which would modulate the Wi-Fi waves being scattered around (by your router, laptop, etc) into a signal that would indicate "open" or "closed".

I think the point was that the large moving metal object (garage door) itself would mess with the signal enough to detect the state without any additional device…

I guess a first good experimental step would be to point a directional Wifi antenna in the direction of the door and monitor what it receives at what strength.

Yup. And the actual implementation difficulty is in setting up the detection/analysis stack.

You could probably adapt this technique https://www.youtube.com/watch?v=aqqEYz38ens to detect your garage door state.

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