Topic
Adaptive beamformer
About: Adaptive beamformer is a research topic. Over the lifetime, 4934 publications have been published within this topic receiving 93100 citations.
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42 citations
TL;DR: This paper experimentally evaluates the interference cancellation performance of various adaptive beamforming schemes with respect to the aforementioned three types of interferences in an attempt to find the most promising adaptive cancellation scheme in practical HFSWR environment.
Abstract: The performance of high-frequency surface wave radar (HFSWR) is known to suffer from external environmental interference and noise, such as cochannel radio-frequency interference from other radiating source, ionospheric clutter, lightning impulsive noise, etc. This paper experimentally evaluates the interference cancellation performance of various adaptive beamforming schemes with respect to the aforementioned three types of interferences in an attempt to find the most promising adaptive cancellation scheme in practical HFSWR environment.
42 citations
24 Aug 1987
TL;DR: The analysis of Parts I and II of the report with this title has been extended into two directions; in the first case, the performance of an adaptive system with respect to signals arriving from directions other than the steering direction is evaluated and the penalty associated with the greater uncertainty of the signal model is shown to be small.
Abstract: : The analysis of Parts I and II of the report with this title has been extended into two directions. In the first case, the performance of an adaptive system with respect to signals arriving from directions other than the steering direction is evaluated. It is shown that these signals are reflected more strongly than would be suggested by the sidelobe levels of the adaptive patterns themselves. In the other case, the detection problem is generalized to include the detection of signals known only to lie in a subspace of the space of steering vectors. Again, performance is derived and the penalty associated with the greater uncertainty of the signal model is shown to be small. The analysis of Part I essentially repeated here, both to keep this report self-contained and to present an alternative version of the basic derivations. Keywords: Adaptive antennas; Signal to noise ratio; Maximum likelihood detection statistical hypothesis testing; Signal to noise ratio; Gaussian noise.
42 citations
17 Jul 2005
TL;DR: Simulation results show an improved robustness of the proposed beamformer as compared to the existing state-of-the-art robust adaptive beamforming techniques.
Abstract: Recently, robust minimum variance (MV) beamforming which optimizes the worst-case performance has been proposed in S.A. Vorobyov et al. (2003), R.G. Lorenz and S.P. Boyd (2005). The worst-case approach, however, might be overly conservative in practical applications. In this paper, we propose a more flexible approach that formulates the robust adaptive beamforming problem as a probability-constrained optimization problem with homogeneous quadratic cost function. Unlike the general probability-constrained problem which can be nonconvex and NP-hard, our problem can be reformulated as a convex nonlinear programming (NLP) problem, and efficiently solved using interior-point methods. Simulation results show an improved robustness of the proposed beamformer as compared to the existing state-of-the-art robust adaptive beamforming techniques
41 citations
TL;DR: A method to predict the amount of noise reduction that can be achieved by a two-microphone adaptive beamformer is presented, based on a model of the acoustic environment in which the presence of one acoustic target-signal source and one acoustic noise source in a reverberant enclosure is assumed.
Abstract: Adaptive beamformers have been proposed as noise reduction schemes for conventional hearing aids and cochlear implants. A method to predict the amount of noise reduction that can be achieved by a two-microphone adaptive beamformer is presented. The prediction is based on a model of the acoustic environment in which the presence of one acoustic target-signal source and one acoustic noise source in a reverberant enclosure is assumed. The acoustic field is sampled using two omnidirectional microphones mounted close to the ears of a user. The model takes eleven different parameters into account, including reverberation time and size of the room, directionality of the acoustic sources, and design parameters of the beamformer itself, including length of the adaptive filter and delay in the target signal path. An approximation to predict the achievable signal-to-noise improvement based on the model is presented. Potential applications as well as limitations of the proposed prediction method are discussed and a FORTRAN subroutine to predict the achievable signal-to-noise improvement is provided. Experimental verification of the predictions is provided in a companion paper [J. Acoust. Soc. Am. 109, 1134 (2001)].
41 citations