Yaakov Buchris

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We propose a spatial combining technique for detection of multicarrier underwater acoustic communication signals using a vertical array of receivers. Instead of estimating the channel for each receiver independently and ignoring the angles of arrival of each of the channel paths, the suggested technique is based on spatially filtering each of the channel(More)
We present a closed-form least squares algorithm for estimating the position and velocity of a source, asynchronously transmitting known dual linear chirp signals, given times of arrival measurements obtained by spatially distributed sensors. The estimates involve less computational load compared to the optimal maximum likelihood estimates. Simulations show(More)
Differential microphone arrays (DMAs) have a great potential to overcome some of the problems of additive arrays and provide high spatial gain relative to their small size. In this work, we present a time-domain formulation for implementing first-order DMAs, which is very important for some applications in which minimal delay is required, such as real-time(More)
In this paper, we develop a Bayesian focusing transformation (BFT) for wideband array processing which utilizes a weighted extension of the wavefield interpolated narrowband generated subspace (WINGS) focusing approach, also derived here. The BFT minimizes the mean-square error of the transformation, thus, achieving improved focusing accuracy over the(More)
Audio-visual voice activity detectors are traditionally based on fixed algorithms and do not consider the quality of the signals in each modality. This could significantly decrease the detector's performance in cases when one of the signals is relatively of poor quality. We proposed an improved solution, which evaluates the signal's quality in each modality(More)
We compare two orthogonal modulation schemes for underwater acoustic sensor network using spread spectrum communication. The first which has been recently published, employs a frequency modulation signals spread by the same code. As an alternative, we propose to modulate the signals by using a different orthogonal code for each signal. Simulations and sea(More)
Design of underwater acoustic sensing and communication systems is a very challenging task due to several channel effects like multipath propagation and Doppler spread. In order to cope with these effects, beamforming techniques have been applied to the design of such systems. The broadband nature of acoustic systems motivates the use of beamformers with(More)
In this paper we propose a scheme of a bank of signal replicas for the synchronization step of an underwater acoustic communication system. Each replica is designed to be Doppler-tolerant for a different section of a possible range of relative radial velocities between the transmitter and the receiver. We suggest a statistical approach for determining the(More)
Circular differential microphone arrays (CDMAs) facilitate compact superdirective beamformers whose beampatterns are nearly frequency invariant, and allow perfect steering for all azimuthal directions. Herein, we eliminate the inherent limitation of symmetric beampatterns associated with a linear geometry, and introduce an analytical asymmetric model for(More)
In this paper, we generalize the recently proposed multi-stage minimum variance distortionless response beamformer to all distortionless linearly constrained minimum variance (LCMV) beamformers with directional constraints. Given N<sub>c</sub> constraints and an M-element microphone array, we propose to divide this array into K-element microphone sub-arrays(More)