Is this looking at the rssi of all networks seen, or playing with the device you're on? Does this work for iPhones?

Yes, it looks at the RSSI of all networks seen, generates distributions of the RSSI signals, and then leverages those distributions using some naive machine learning to classify the location.

It does not work for iPhones. Unfortunately, Apple keeps the WiFi scanning in a "private" api which would require jailbreaking because, as far as I know, use of those apis won't get past the app-store review.

So, for now it only works on Android and on laptops/single-board computers using a Python script (links to app and script in Github).

Any chance of getting it to work natively on android as a standalone library without cordova? Being able to integrate a library over Gradle into an existing app would be really really nice.

That's a good idea! I'll look into it.

Why not just have the iPhone app act as a Bluetooth LE beacon? You can do that without jailbreaking, and BLE signals are in the 2.5GHz band.

As I understand it, the technique used is to create a map of the room by listening and recording all RSSI from all stations and training classifiers. Then the app listen to all stations, input the RSSIs, and the classifiers give you back a location in the room. So the iPhone is supposed to just passively listen, not emit any signal – but apparently you can't access all RSSIs values of your surrounding stations via public APIs on iOS.

In any case, it's a clever way to map the room by its spectrum landscape :-)

Thanks for that explanation. Makes sense.

If you are interested, we are doing something similar at http://www.smartertime.com with an automated learning and update phase. It gives a "one click and forget" location system. All algorithms run on the phone, and the user only has to tell the app things like "this is my kitchen".