Passive indoor-localization using echoes of ultrasound signals

In this paper, we present our novel indoor-localization system. The system uses only short inaudible acoustic signals to locate acoustically passive objects in a room. Moving objects can be detected as well as resting objects. The localization device consists of a transmitter (speaker) and a multi-channel receiver with up to eight receivers (microphones). The total time-of-flight path from the speaker to the microphones is the round-trip-time of the signal from the speaker to the reflecting object and back to the microphones. Therefore, a localization algorithm is used to translate the timing into object coordinates. By using a simple approach of direct intersection, the 3D-coordinates of the reflecting surface of the target can be derived. In an experiment, we demonstrate the functionality of this approach.