Patent Document ID: 7630502
Application ID: 10941961
Patent Flag: 1

Claim One:
1. In an audio conferencing system having a loudspeaker for outputting and a plurality of M microphones for inputting their respective signals, a combined beamformer comprising a plurality of J individual beamformers for modifying the gain of each of said signals by respective beamformer weight vectors of length M, Wj(v),where j=1 to J, to simultaneously create respective beams each pointing in a different look direction, said combined beamformer having a common response to said loudspeaker signal without having to specify an exact value of said (a) response and being characterized by a minimum variance condition that combines all of said beamformer weight vectors simultaneously as Min W ⁡ ( W H ⁡ ( v ) ⁢ ⁢ R ⁡ ( v ) ⁢ ⁢ W ⁡ ( v ) ) subject to the constraint W H (v)C(v)=G(v) where W j (v) is the vector of length M×J formed of concatenated vectors Wj(v), W H (v) denotes the Hermitian transpose of W(v), R(v) is a concatenated noise correlation matrix of size M×J by M×J, C(v) is a uniform coupling constraint matrix expressed as a number involving more than one beamformer of linear constraints on the components of the concatenated weights vector, W(v) and G(v) is a constraint response vector, a unique solution to said minimum variance condition being given by 
 W ( v )= R −1 ( v ) C ( v )[ C H ( v ) R −1 ( v ) C ( v )] −1 G H ( v ) such that individual ones of said beamformers satisfy said uniform coupling constraint and is expressed as a linear function of the combined weight vectors of said beamformers and are optimal in terms of said minimum variance condition.