ZHOU Shengzeng DU Xuanmin

(Shanghai Marine Electronic Equipment Research Institute Shanghai 201108)

Received Dec. 1, 2009

Revised Jan. 20, 2010

Abstract  The conventional MVDR adaptive beamformer is a high-resolution narrowband beamformer which estimates the optimal beamforming weights using narrowband CSDM of real acoustic field. In practical applications, MVDR algorithm needs long observation time to estimate the covariance matrix. This inherent property makes it difficult to localize fast-moving targets. For wideband signals, MVDR algorithm needs inverting every CSDM which increases the computational demands. For correlated sources, the performance of MVDR will degrade dramatically because the signals will cancel each other. A fast-convergent MVDR algorithm based on suband subarray processing is proposed. The full frequency band is divided into sets of subbands and the line array is divided into sets of subarrays. For every subband the STCM of reduced dimensions is calculated. Then adaptive beamforming weight of fast-convergent MVDR algorithm and spatial spectrum estimation are obtained. At the same time, spatial spectrum estimation can be made for correlated sources using the two-sided spatial smoothing method. Results of simulation and trial data show that the proposed method has high-resolution and near-instantaneous convergence property, two-sided spatial smoothing has satisfactory validity of decorrelation.

PACS numbers:43.60,43.30