Application of orthogonal perturbation sequences to adaptive beamforming

The application of orthogonal perturbation sequences to adaptive beamforming is considered. The perturbation approach is relevant when all the array element signals in an array are not accessible but the array weights are independently adjustable. The perturbation sequences can be used to provide an estimate of the gradient required for adaptive beamforming. A unified analysis of the performance of orthogonal perturbation sequences is presented, and the performance of some specific sequences is investigated. It is demonstrated that for time multiplex perturbation sequences the penality incurred because of the use of perturbations for gradient estimation in adpative beamforming is an increase by a factor
N
in the system time constants.