MoBat is a combined hard- and software system designed to locate and track multiple unmodified mobile devices on any regular table using passive acoustic sensing. Barely audible sound pulses are emitted from mobile devices, picked up by four microphones located in the corners of the surface and processed in a low-latency pipeline to extract position data. We demonstrate an average positional accuracy and precision of about 3 cm on a table of 1 m x 2 m size, and discuss possible usage scenarios regarding proxemics and tangible interaction.

A conference poster about MoBat was presented at ITS 2015 ( Source code is available on GitHub at