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Plane-wave imaging plays a highly significant role o wing to the special demand for high frame rate, however, its po or image quality hinders its application in ultrasound industrie s. Many scholars have attempted to give a wide variety of soluti ons to improve the image quality, however, each of them has li mitations or compromises. In this study, we improve the spatio -temporally smoothed factor...
The technique of non-invasive cortical bone quality assessment using ultrasound axial transmission has attracted considerable attention. Estimating the phase velocity and the attenuation of the absorbing plate will assist the assessment. Among several techniques proposed for these purposes, many employ either a thresholding process or a peak search process. The thresholding process uses the intensity...
Experimental results from volumetric 3-D vector flow measurements using a 62+62 row-column addressed (RCA) array are presented. A plane-by-plane steered transmit sequence and its post processing steps are described for obtaining 3-D vector flow in a volume. A modified version of the transverse oscillation (TO) velocity estimator is used, which exploits the focal lines generated with the tall elements...
The shift to software beamforming has inspired a myriad of adaptive beamformers. Some of these overestimate which signals originate from sidelobes and which originate from the mainlobe. This results in a Dark Region Artifact (DRA) next to hyperechoic targets. We investigate this artifact for seven beamformers: Delay-And-Sum (DAS), the Coherence Factor (CF), Generalized Coherence Factor (GCF), Phase...
The non-invasive cortical bone quality assessments using ultrasound axial transmission technique have attracted strong attention. The estimation of phase velocity and attenuation of absorbing plate should help the assessment. To get the high-resolution estimation, we employ an adaptive beamforming technique that uses an eigenvalue decomposition. The technique can estimate not only the phase velocities...
In this work, a vector flow imaging (VFI) method based on synthetic aperture sequential beamforming and directional transverse oscillation (TO) is implemented in a commercial tablet. In comparison with previous tablet-based flow imaging implementations, the velocity estimation is extended to a 2-D angle-independent setup. The received data are pre-beamformed in the probe, which leads to a 64x data...
Recent advancements of ultrasound vector Doppler techniques have boosted the investigation of 2D regions of interest (ROIs). Several methods were proposed, but their implementation on commercial systems is still limited by technical difficulties. First, the investigation of wide ROIs at high frame rate requires the transmission of plane waves and parallel beamforming in reception. Furthermore, the...
Recent advancements in ultrasound vector Doppler (VD) techniques have boosted the investigation of 2D regions of interest (ROIs). Several methods have been proposed, but their implementation on commercial systems is still limited. First, the investigation of wide ROIs at high frame rate requires the transmission of plane waves (PWs) and parallel beamforming in reception. Furthermore, the extraction...
The industrial demands for accurate localization systems have been rapidly increasing after the introduction of the Internet of Things (IoT) concept. Self localization and tracking transmitting sources are considered essential parts of IoT applications. In this paper we studied the possibility of applying angle of arrival (AoA) estimations to localize an IoT transceiver device in an indoor environment...
In this paper, a new compressive sensing (CS)-based direction of arrival (DOA) estimation technique using the Dantzig selector is proposed. The proposed scheme can identify more source signals than the number of sensors used, without requiring an a priori knowledge of the number of source signals to be estimated and without any constraint or assumption about the nature of the signal sources using...
Direction-of-arrival (DOA) estimation is a ubiquitous task in array processing. The conventional MUltiple SIgnal Classification (MUSIC) method is search-based and often computationally expensive, particularly in the application of joint azimuth and elevation estimation. In this paper, we propose an adaptive 2-dimensional direction finding framework to track multiple moving targets for arbitrary array...
We study the problem of wideband direction of arrival (DoA) estimation by joint optimisation of array and spatial sparsity. Two-step iterative process is proposed. In the first step, the wideband signal is reshaped and used as the input to derive the weight coefficients using a sparse array optimisation method. The weights are then used to scale the observed signal model for which a compressive sensing...
In this paper, we comparatively study alternative dictionary designs for recently proposed meeting diarization and adaptive beamforming based on a probabilistic spatial dictionary. This dictionary models the feature distribution for each possible direction of arrival (DOA) of speech signals and the feature distribution for background noise. The dictionary enables online DOA detection, which in turn...
Given a collection of M experimentally measured subspaces, and a model-based subspace, this paper addresses the problem of finding a subspace that approximates the collection, under the constraint that it intersects the model-based subspace in a predetermined number of dimensions. This constrained subspace estimation (CSE) problem arises in applications such as beamforming, where the model-based subspace...
A distortionless speech extraction in a reverberant environment can be achieved by an application of a beamforming algorithm, provided that the relative transfer functions (RTFs) of the sources and the covariance matrix of the noise are known. In this contribution, we consider the RTF identification challenge in a multi-source scenario. We propose a successive RTF identification (SRI), based on a...
We focus on the problem of source enumeration in large arrays with relatively few samples, which is solved in this paper by using a statistic of corrected Rao's score test (CRST) via the generalized Bayesian information criterion (GBIC). Under the white noise assumption, the covariance matrix of the noise subspace components of the observations is proportional to an identity matrix, and this structure...
Sparse arrays can generate a larger aperture than traditional uniform linear arrays (ULA) and offer enhanced degrees-of-freedom (DOFs) which can be exploited in both beamforming and direction-of-arrival (DOA) estimation. One class of sparse arrays is the coprime array, composed of two uniform linear subarrays which yield an effective difference co-array with higher number of DOFs. In this work, we...
Co-prime arrays have gained in popularity as an efficient way to estimate second order statistics at the Nyquist rate from sub-Nyquist samples without any sparsity constraint. We derive an expression for the degrees of freedom and the number of consecutive values in the difference set for the prototype co-prime array. This work shows that, under the wide sense stationarity (WSS) condition, larger...
Estimating the direction of arrival (DOA) in sensor arrays is a crucial task in array signal processing systems. This task becomes more difficult when the sensors have gain/phase uncertainty. We have addressed this issue by modeling the problem as a combination of two sparse components, the DOA vector and the gain/phase uncertainty vector. Therefore, a sparse decomposition technique is suggested to...
In this paper, we propose a novel Vandermonde decomposition-based direction-of-arrival (DOA) estimation algorithm by using a coprime array, where increased number of degrees-of-freedom (DOFs) can be achieved in an off-grid manner. Specifically, the equivalent statistics corresponding to an augmented virtual uniform linear array are first derived from the coprime array received signals, and the resulting...
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