Adaptive beamformer

About: Adaptive beamformer is a research topic. Over the lifetime, 4934 publications have been published within this topic receiving 93100 citations.

Knowledge-aided robust adaptive beamforming with small snapshots

Abstract: A robust adaptive beamforming method is proposed to combat arbitrary array steering vector (SV) mismatches and small sample size. First, with the imprecise knowledge of the array manifold and angular sectors of the interferences, an a priori covariance matrix can be acquired. Secondly, a theoretically optimal covariance matrix can be obtained by combining an a priori covariance matrix with the sample covariance matrix. Finally, the mismatch vector between the actual and presumed SV can be estimated by solving a quadratic convex optimisation problem.

Digital beamforming and filtering circuit

Abstract: A beamformer system is disclosed which includes an array of sensors such asydrophones which produce signals from which information relating to a target is to be determined. The beamformer system includes a channel for each sensor, the channel including a varable length shift register which provides bulk delay to received signals, a FIR interpolation filter which provides vernier delay and shading. The system also includes a summation tree which adds the received signals and a sign extension/bit reversal filter to avoid authmetic overflow.

Space-time processing for suppression of bottom reverberation

Abstract: The major problem for sonars operating in shallow water is the detection of low Doppler targets in the presence of severe bottom reverberation For a modern sonar with an azimuthally omni-directional transmitter; the Doppler of bottom reverberation is proportional to /spl nu/cos /spl theta/ where /spl nu/ is the speed of the sonar platform and /spl theta/ is measured from the bow or heading direction For a towed array receiver, reverberation of various Doppler arriving on sidelobes limits the effectiveness of advanced waveforms This smearing of sidelobe reverberation over a Doppler range of /spl plusmn//spl nu/ makes it difficult to detect targets with speeds less than that of the sonar platform Standard adaptive beamforming algorithms are ineffective due to the conflict between desire for narrow frequency bins for good Doppler confinement and wide frequency bins for rapid convergence We present space-time processing algorithms that overcome these difficulties and permit the detection of low Doppler targets from moving platforms

Direction-of-arrival estimation of correlated sources by adaptive beamforming

Abstract: This correspondence has analyzed the capability of minimum energy optimum/adaptive beamformer to estimate the bearings of two closely spaced narrowband equal-energy correlated sources. The analytical expression for minimum angular separation for resolution of such sources as a function of the correlation coefficient, signal power, and the parameters of the adaptive processor is derived. The approach of spatial smoothing is considered. The simple problem of definition of optimal size of the subarray for highly correlated sources is examined. Results of computer simulations are included to support our analysis.

Musical Noise Controllable Algorithm of Channelwise Spectral Subtraction and Adaptive Beamforming Based on Higher Order Statistics

Abstract: In this paper, we propose a musical-noise-controllable algorithm for array signal processing with the aim for high-performance and high-quality noise reduction. Recently, many methods of integrating linear microphone array signal processing and nonlinear signal processing for noise reduction have been studied, but these methods often suffer from the problem of musical noise. In the proposed algorithm, channelwise spectral subtraction is applied before adaptive array signal processing. We also introduce a new automatic control algorithm to obtain the subtraction strength parameter used in the spectral subtraction, which depends on the amount of generated musical noise, measured by higher order statistics. We confirm the effectiveness of the proposed algorithm via objective and subjective evaluations.