Inspiration

As a kid, who hasn't imagined seeing through walls like Superman can? You find people trapped in collapsed buildings, search your home for intruders, spy on your friends (not endorsed by the Wifi-Vison team); the possibilities are endless.

What it does

Wifi-vision sees through walls with wifi, using only commonly available resources. We use the same concept as what MRI's, or xrays use. Send a signal through a solid object, and measure how the wave signal is changed. However, wifi has the distinct advantage that it is already broadcasting in every household, allowing us to easily(relative) scan an area. The data is picked up with standard wifi receivers; the same ones that is present in all your phones, laptops, and other internet devices.

How we built it

The technology works by scanning through an area, and measuring the strength of the wifi signal. Lower quality signals that the signal is travelling through more objects (or interference), while higher signals indicate clear space. By mounting wifi receivers and sweeping them along an area, we can measure an entire room. After doing a parsing step and cleaning up interference in the data, a density map can be displayed, showing similar data to what you'd imagine an xray scan would look like.

Challenges we ran into

Hardware is finicky, and wifi has alot of interference. Wifi signals aren't clearcut lines to a wifi receiver; they are like ripples in water; they bounce around through a room. However, the good part is that the only signal that we really care about is the strongest one. By filtering the data, we can isolate the strongest signal to display the most accurate data.

Accomplishments that we're proud of

We're very proud that in just one weekend, we managed to build an "xray machine" out of scratch, using just wifi signals! Even though we ran into many hiccups along the way, especially with setting up hardware, we were able to get everything functional in the end.

What we learned

We learned alot about building electronics; it took half a dozen chips, a belt pulley system, and a whole pile of wire to link all the parts together. Also, we learned alot of details about the specifics of isolating a strong wifi signal.

What's next for Wifi-Vision

What we can currently create is a 2d density map of an area, using one receiver. However, many larger places (like restaurants, apartment buildings, lobbies, etc.) use more than one receiver. What this means is you can get multiple 2d density maps from different angles, and stitch together these datasets to create a 3d map instead. Given time, that is the next goal we would work for.

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