AN IN-AIR SONAR SYSTEM AND A METHOD THEREFOR

This disclosure relates to an in-air sonar system for determining location and velocity information of objects in an environment, the in- air sonar system comprising at least two emitters forming an emitter array (111) to emit respective sound signals into the environment; at least two receivers forming a receiver array (112) to receive sound signals from the environment; and a processing unit (120) to perform: obtaining, from the receivers (112), respective received sound signals comprising the emitted sound signal reflected from objects (13, 14, 15) in the environment; calculating, from the respective received sound signals, respective velocity-dependent range maps; deriving, from the calculated velocity-dependent range maps and the spatial diversity of the emitters (111) and of the receivers (112), a velocity- dependent range-direction map comprising range information as a function of a received direction; determining therefrom a location of the respective objects (13, 14, 15); and extracting, from the velocity- dependent range maps and the spatial diversity of the receivers (112), a velocity of the respective objects (13, 14, 15) based on the determined location. A set of Doppler-shifted sound signals are generated by frequency shifting the sound signal emitted by the respective emitters and stored in a pre-calculated signal bank (115). The deriving step comprises beamform processing to compensate for delay variations. The determining step comprises clustering. Processing the sound signals separately improves the resolution of the obtained location and velocity information and therefore the overall reliability of the in-air sonar system.