Patent Document ID: 20050232441
Application ID: 10941961
Patent Flag: 0

Claim One:
1. In an audio conferencing system having a loudspeaker and a plurality of M microphones for outputting 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, W j (v), where j=1 to J, to create respective beams in respective look directions, said combined beamformer 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(v) is the vector of length M×J formed of concatenated vectors W j (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 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 are optimal in terms of said minimum variance condition.