Patent ID: 7277116

Claim:
A method for controlling movable video cameras ( 15 ) comprising the following steps: setting up an array of microphones ( 10 ) to capture a sound event; for each pair of microphones (j, 1 ) consisting of a selected microphone and each of the remaining microphones, performing a Fourier analysis to determine the normalized cross correlation (normalized cross-power spectrum) of the sampled signals, generated by the microphones S i ⁡ ( ω k ) ⁢ S j * ⁡ ( ω k )  S i ⁡ ( ω k )  ⁢  S j * ⁡ ( ω k )  = ⅇ - ⅈ ⁢ ⁢ ω ⁢ k ⁢ Δ ij , k ∈ [ - N / 2 , + N / 2 ] ( ii ) where N is the number of samples; filtering the normalized cross-power spectrum using a normalized function tending to zero on the boundary; performing the inverse transform on the normalized, filtered cross-power spectrum; estimating, for each pair of microphones, the delay time Δ j1 of arrival of the sound wavefront on the microphones, by determining in the time domain the maximum value of the inverse transform function; determining the space-time coordinates of the sound event by solving the linear equation system Aξ=b,AεR mx4 ξεR 4 ,bεR m , m≧ 5 (v) directing the video cameras ( 15 ) at the point whose space coordinates are those determined by solving the equation system (v).