I noticed this effect when I was working with Zigbee mesh networks (which usually operate on 2.4 GHz like wifi). You could clearly see the S/N ratio change betw

I noticed this effect when I was working with Zigbee mesh networks (which usually operate on 2.4 GHz like wifi). You could clearly see the S/N ratio change between working and non-working hours as people in the office came and went. I always thought it could be used as an occupancy sensor for home or building automation (I'm surprised they aren't doing this already for hotels and other commercial buildings)