Your TV can see through walls

Wait for people to learn about that you can listen in virtually anywhere through fiber-optic cables, as sound waves are enough to redirect the light in the cable to a measurable degree by "bending" the cable itself. Special devices to filter these variances out and transform them back to audio signals are a thing. It's only per line though, as any repeating device will just output a new cleaned up signal again.

Oh well, there have always been ways to snoop on someone like that. Back in the day it was CRTs emitting measurable waves through the neighborhood, with some papers even going as far as restoring the displayed image through a wall. Nowadays it's fiber and WiFi, and those seem to be much easier to work with even. Plus everyone carries a device that is tracked by their mobile provider's cell network. shrug

Several years back we actually made use of the principle mentioned in this post, to more systematically count traffic on the roads [1]. In our case we used LTE/4G radio, and we could even estimate the direction of travel, as well as the type of traffic (pedestrian, small vehicles, large vehicles). It was more accurate than Google Maps because it was independent of the moving phone, i.e. it was "sensing the obstacles in the environment".

[1] "Traffic Flow Estimation using LTE Radio Frequency Counters and Machine Learning", https://arxiv.org/abs/2101.09143

As anyone observed who had a TV with just basic analog terrestrial antennas, before cable and satellite dishes - it does make a difference to the signal, when and where you stand and countless pieces of physical comedy in TV shows incorporated that.

See these for a very low cost (<$10) method for observing WiFi and some LTE spectra:

https://news.ycombinator.com/item?id=49922674

https://espargos.net/espsdr/

I recall there being an MIT study where they were literally using rf signals to see through walls like an X-ray.

I even had a startup that used path loss and scattering from rf photons to accurately estimate traffic flow using 4G [1].

[1] https://arxiv.org/abs/2101.09143

Amazing book about similar topics: “Silence on the wire” by Michal Zalewski

https://www.amazon.de/Silence-Wire-Passive-Reconnaissance-In...

So, a bad actor can now know when I'm at my house or not, I'm sure that's fine and won't be problematic

Thank you for more paranoia

See also: Van Eck Phreaking https://en.wikipedia.org/wiki/Van_Eck_phreaking

Now, about the wifi part, why isn't there an Home Assistant extension that detects already room presence magically exploiting all of this??

see also, presence detection of humans via wifi signals: https://arxiv.org/html/2308.06773v2

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