Journal ArticleDOI
Response of sample covariance based MVDR beamformer to imperfect look and inhomogeneities
TLDR
Exact means and variances are given for the SCR MVDR beamformer output accounting simultaneously for finite sample support, imperfect look, and inhomogeneities demonstrating biased signal estimates and potentially extreme vulnerability to undernulled interference and surprise jammers.Abstract:
The sample covariance based (SCB) minimum variance distortionless response (MVDR) beamformer has desirable properties under ideal homogeneous data conditions with perfect look. Such properties include maximum-likelihood optimality yielding an unbiased asymptotically efficient estimate of the signal parameter. When target array response mismatch exists and inhomogeneities are present, however, its performance can degrade considerably. Exact means and variances are given for the SCR MVDR beamformer output accounting simultaneously for finite sample support, imperfect look, and inhomogeneities demonstrating biased signal estimates and potentially extreme vulnerability to undernulled interference and surprise jammers.read more
Citations
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Journal ArticleDOI
Performance of a class of adaptive detection algorithms in nonhomogeneous environments
TL;DR: It is demonstrated through theoretic analysis that in the presence of undernulled interference, the ASB is a pliable false alarm regulatory (FAR) detector that maintains good target sensitivity.
Journal ArticleDOI
Application of an MEG eigenspace beamformer to reconstructing spatio‐temporal activities of neural sources
TL;DR: The eigenspace‐based beamformer is applied to reconstruct spatio‐temporal activities of neural sources from MEG data to produce a SNR considerably higher than that of the minimum‐variance beamformer in practical situations.
Journal ArticleDOI
Outlier resistant adaptive matched filtering
TL;DR: Four new algorithms that censor outliers are presented which are derived via approximation to the MLE solution and one of the censoring algorithms, called the reiterative censored fast maximum likelihood (CFML) technique is significantly superior to the other three censoring methods in stressful outlier scenarios.
Journal ArticleDOI
A Bayesian Approach to Adaptive Detection in Nonhomogeneous Environments
TL;DR: Two Bayesian versions of the adaptive matched filter are presented, where the conventional maximum likelihood estimate of the primary data covariance matrix is replaced either by its minimum mean-square error estimate or by its maximum a posteriori estimate.
Journal ArticleDOI
Mean-squared error and threshold SNR prediction of maximum-likelihood signal parameter estimation with estimated colored noise covariances
TL;DR: A new modification of the CRB involving a complex central beta random variable different from, but analogous to the Reed, Mallett, and Brennan beta loss factor provides a working solution to this problem, facilitating MSE prediction well into the threshold region with remarkable accuracy.
References
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Journal ArticleDOI
Rapid Convergence Rate in Adaptive Arrays
TL;DR: A direct method of adaptive weight computation, based on a sample covariance matrix of the noise field, has been found to provide very rapid convergence in all cases, i.e., independent of the eigenvalue distribution.
Proceedings ArticleDOI
Space-time adaptive processing for airborne radar
TL;DR: An overview of partially adaptive STAP approaches is provided and the effect of STAP on angle and Doppler accuracy is described, and an approach for joint angle and doppler estimation in a STAP radar is described.
Journal ArticleDOI
Resolving power and sensitivity to mismatch of optimum array processors
TL;DR: In this paper, the effects of mismatch on a conventional beamformer and two optimum beamformers are compared and conditions for the resolution of closely spaced sources by an optimum beamformer are presented.
Journal ArticleDOI
PDF's, confidence regions, and relevant statistics for a class of sample covariance-based array processors
TL;DR: It is shown that the exact joint PDFs for the weight vectors/matrices of the aforementioned SCB array processors are a linear transformation from a complex multivariate extension of the standardized t-distribution.
Journal ArticleDOI
Derived PDF of maximum likelihood signal estimator which employs an estimated noise covariance
TL;DR: It is demonstrated that there exists a dynamic tradeoff between signal-to-noise ratio (SNR) and noise adaptivity as the dimensionality of the array data is varied, suggesting the existence of an optimal array data dimension that will yield the best performance.