Patent ID: 8638641

Claim:
A method for the passive tracking of a plurality of objects emitting respective signals in the form of a series of predetermined sounds, comprising the following steps: during successive processing time windows, acquiring raw analogue signals from a plurality of sensors, wherein at least some of the raw analogue signals correspond to the signals emitted by the plurality of objects; converting the raw analogue signals into digital data by sampling at a certain sampling frequency; filtering the digital data to eliminate spurious noise; eliminating echoes in the filtered signal by performing the following steps: determining an envelope of the filtered digital data; integrating the envelope on time windows; and comparing a result of the integrated envelope with a predetermined threshold, wherein if the result is below the predetermined threshold, a signal corresponding to the result is one of the predetermined sounds and is stored in a memory and, if the result is above the said predetermined threshold, a signal corresponding to the result is an echo and is eliminated; obtaining, for each pair of sensors and each processing window, potential values (TDOA) of differences in arrival time of the stored signals to reach two distinct sensors; for each pair of sensors, verifying the coherence of the TDOAs, and selecting a number (nbTDOA) of filtered TDOAs coherent with each other; and from the filtered and coherent TDOAs, determining the successive instantaneous positions of the sources of the predetermined sounds by non-linear regression and deducing the path of the plural objects in their environment in real time.