The WiSee proof-of-concept is implemented in GNURadio using the USRP-N210 hardware.

Each USRP is equipped with a XCVR2450 daughterboard, and communicates on a 10 MHz channel at 5 GHz. Since USRPN210 boards cannot support multiple daughterboards, we built a MIMO receiver by combining multiple USRP-N210s using an external clock. In our evaluation, we use MIMO receivers that have up to five antennas. We use single antenna USRP-N210s as transmitters.

So basically, they are using 6+ USRPs at $1400+ each to do these experiments. However, since each USRP is communicating on a 10MHz channel at 5GHz, someone with between two and five MIMO 802.11n Wi-Fi devices could theoretically do the same.

[1] http://wisee.cs.washington.edu/wisee_paper.pdf

http://www.extremetech.com/extreme/133936-using-wifi-to-see-...

http://www.youtube.com/watch?v=wK_u8-UQmOs

Send ultra sound from the laptop speaker, pickup with mic, detects hand guestures.

What's the range on this technology, and what happens if we move the router around with us? Maybe we take it to a new building and plug it in there? Or maybe we can use the wifi modules on phones to do this also? It sounds like a great scanning device. And how long before we can also see huge chunks of metal or strong magnets with this technology, based on how radio waves interact with them?

I'm not sure if I qualify as one of the "privacy folk" or not, but I would say "As long as the police cannot compel you to install the thing and switch it on, or have an AI system issue search warrants in seconds based on what the machine reports." Unfortunately I think we will have both of those things 20 years from now.

I don't have the background to try to pull the limits up out of the white paper, but I think the current implementation is more or less looking for movement in 1 dimension (towards and away from the receiver). So plenty of time to decide whether radio waves are revealing anything that sight and sound are not.

Failures where the gesture is recognized as another gesture would be a lot more annoying.

Anyway, if you look up through-wall radar detection, most of the implementations use S-band radar, and it is probably safe to assume that it's already been figured out how to use wifi stations and devices already in place emitting signals to each other, rather than always needing to bring additional equipment.

With regard to privacy though, it seems like it would be data and computationally intensive to track the movements of people in a large number of houses.

Let's say that a hypothetical application could only detect velocities away from or toward the base station, but no directional information. With each movement you make it would build a set of hypotheses about your location. Then when you make another movement, it would need to branch out, and create an entire set of hypotheses for each hypothesis in the previous set, and so on with each movement. While the program could abandon entire branches when they showed you walking through a wall, it would still grow very quickly.

Though it is possible to mine data of cell phone locations and CC television cameras after the fact, it seems like (if my understanding of how the technology would work is anything near reality) it is simply too difficult to collect a lot of information about people's movements in their homes without a specific prior reason to justify the expense.

Anyway, perhaps rather than tinfoil hats, people worried about surveillance should hang lots of mobile sculptures in their houses to create confounding noise instead.

Using these together significantly reduces the chance of a false positive than just using one type on its own.

So, you could use this to replace the microwave sensor in the dual tech sensors but you would still need the PIR.

The article is talking about phased array stuff, stuff you can't do with stock wifi equipment. All the regular wifi equipment is just providing the "light" the special receiver needs to see.

Or are you just spamming?