Security consultant Joseph Greenwood looked at the leaked documents listing the NSA's hardware surveillance gadgets and decided to build his own. He mimicked the Sparrow II, a lightweight stand-alone WLAN collection system designed to be deployed by small drones.

December 2013 Der Spiegel reported on the existence of the ANT catalog. A 50 page catalog listing devices created by the ANT division for surveillance and intrusion purposes.

It featured the Sparrow II, a small devise used to map and log access points and associate them with a location. Light enough to be mounted on a drone, it can do so unobtrusively from the air. It also comes with $6000 price tag.

Joseph Greenwood of Hyperion Bristol decided to build an open source version with an open source price: around $170.

For a computer he used a Raspberry Pi, a USB WiFi adapter for WLAN detection, a GPS module for location pinpointing and a USB battery for stand-alone operation. HyperionBristol provides a detailed how-to.