Journal articles: 'Beamformer'

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Picou, Erin M., and Todd A. Ricketts. "An Evaluation of Hearing Aid Beamforming Microphone Arrays in a Noisy Laboratory Setting." Journal of the American Academy of Audiology 30, no. 02 (February 2019): 131–44. http://dx.doi.org/10.3766/jaaa.17090.

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AbstractPeople with hearing loss experience difficulty understanding speech in noisy environments. Beamforming microphone arrays in hearing aids can improve the signal-to-noise ratio (SNR) and thus also speech recognition and subjective ratings. Unilateral beamformer arrays, also known as directional microphones, accomplish this improvement using two microphones in one hearing aid. Bilateral beamformer arrays, which combine information across four microphones in a bilateral fitting, further improve the SNR. Early bilateral beamformers were static with fixed attenuation patterns. Recently adaptive, bilateral beamformers have been introduced in commercial hearing aids.The purpose of this article was to evaluate the potential benefits of adaptive unilateral and bilateral beamformers for improving sentence recognition and subjective ratings in a laboratory setting. A secondary purpose was to identify potential participant factors that explain some of the variability in beamformer benefit.Participants were fitted with study hearing aids equipped with commercially available adaptive unilateral and bilateral beamformers. Participants completed sentence recognition testing in background noise using three hearing aid settings (omnidirectional, unilateral beamformer, bilateral beamformer) and two noise source configurations (surround, side). After each condition, participants made subjective ratings of their perceived work, desire to control the situation, willingness to give up, and tiredness.Eighteen adults (50–80 yr, M = 66.2, σ = 8.6) with symmetrical mild sloping to severe hearing loss participated.Sentence recognition scores and subjective ratings were analyzed separately using generalized linear models with two within-subject factors (hearing aid microphone and noise configuration). Two benefit scores were calculated: (1) unilateral beamformer benefit (relative to performance with omnidirectional) and (2) additional bilateral beamformer benefit (relative to performance with unilateral beamformer). Hierarchical multiple linear regression was used to determine if beamformer benefit was associated with participant factors (age, degree of hearing loss, unaided speech in noise ability, spatial release from masking, and performance in omnidirectional).Sentence recognition and subjective ratings of work, control, and tiredness were better with both types of beamformers relative to the omnidirectional conditions. In addition, the bilateral beamformer offered small additional improvements relative to the unilateral beamformer in terms of sentence recognition and subjective ratings of tiredness. Speech recognition performance and subjective ratings were generally independent of noise configuration. Performance in the omnidirectional setting and pure-tone average were independently related to unilateral beamformer benefits. Those with the lowest performance or the largest degree of hearing loss benefited the most. No factors were significantly related to additional bilateral beamformer benefit.Adaptive bilateral beamformers offer additional advantages over adaptive unilateral beamformers in hearing aids. The small additional advantages with the adaptive beamformer are comparable to those reported in the literature with static beamformers. Although the additional benefits are small, they positively affected subjective ratings of tiredness. These data suggest that adaptive bilateral beamformers have the potential to improve listening in difficult situations for hearing aid users. In addition, patients who struggle the most without beamforming microphones may also benefit the most from the technology.

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Chau, Gustavo, Jeremy Dahl, and Roberto Lavarello. "Effects of Phase Aberration and Phase Aberration Correction on the Minimum Variance Beamformer." Ultrasonic Imaging 40, no. 1 (July 13, 2017): 15–34. http://dx.doi.org/10.1177/0161734617717768.

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The minimum variance (MV) beamformer has the potential to enhance the resolution and contrast of ultrasound images but is sensitive to steering vector errors. Robust MV beamformers have been proposed but mainly evaluated in the presence of gross sound speed mismatches, and the impact of phase aberration correction (PAC) methods in mitigating the effects of phase aberration in MV beamformed images has not been explored. In this study, an analysis of the effects of aberration on conventional MV and eigenspace MV (ESMV) beamformers is carried out. In addition, the impact of three PAC algorithms on the performance of MV beamforming is analyzed. The different beamformers were tested on simulated data and on experimental data corrupted with electronic and tissue-based aberration. It is shown that all gains in performance of the MV beamformer with respect to delay-and-sum (DAS) are lost at high aberration strengths. For instance, with an electronic aberration of 60 ns, the lateral resolution of DAS degrades by 17% while MV degrades by 73% with respect to the images with no aberration. Moreover, although ESMV shows robustness at low aberration levels, its degradation at higher aberrations is approximately the same as that of regular MV. It is also shown that basic PAC methods improve the aberrated MV beamformer. For example, in the case of electronic aberration, multi-lag reduces degradation in lateral resolution from 73% to 28% and contrast loss from 85% to 25%. These enhancements allow the combination of MV and PAC to outperform DAS and PAC and ESMV in moderate and strong aberrations. We conclude that the effect of aberration on the MV beamformer is stronger than previously reported in the literature and that PAC is needed to improve its clinical potential.

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Wang, Yuzhu, Jingdong Chen, Jacob Benesty, Jilu Jin, and Gongping Huang. "Binaural Heterophasic Superdirective Beamforming." Sensors 21, no. 1 (December 25, 2020): 74. http://dx.doi.org/10.3390/s21010074.

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The superdirective beamformer, while attractive for processing broadband acoustic signals, often suffers from the problem of white noise amplification. So, its application requires well-designed acoustic arrays with sensors of extremely low self-noise level, which is difficult if not impossible to attain. In this paper, a new binaural superdirective beamformer is proposed, which is divided into two sub-beamformers. Based on studies and facts in psychoacoustics, these two filters are designed in such a way that they are orthogonal to each other to make the white noise components in the binaural beamforming outputs incoherent while maximizing the output interaural coherence of the diffuse noise, which is important for the brain to localize the sound source of interest. As a result, the signal of interest in the binaural superdirective beamformer’s outputs is in phase but the white noise components in the outputs are random phase, so the human auditory system can better separate the acoustic signal of interest from white noise by listening to the outputs of the proposed approach. Experimental results show that the derived binaural superdirective beamformer is superior to its conventional monaural counterpart.

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Tao, Jian-wu, and Wen-xiu Chang. "The Generalized Sidelobe Canceller Based on Quaternion Widely Linear Processing." Scientific World Journal 2014 (2014): 1–12. http://dx.doi.org/10.1155/2014/942923.

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We investigate the problem of quaternion beamforming based on widely linear processing. First, a quaternion model of linear symmetric array with two-component electromagnetic (EM) vector sensors is presented. Based on array’s quaternion model, we propose the general expression of a quaternionsemiwidelylinear (QSWL) beamformer. Unlike the complex widely linear beamformer, the QSWL beamformer is based on the simultaneous operation on the quaternion vector, which is composed of two jointly proper complex vectors, and its involution counterpart. Second, we propose a useful implementation of QSWL beamformer, that is, QSWL generalized sidelobe canceller (GSC), and derive the simple expressions of the weight vectors. The QSWL GSC consists of two-stage beamformers. By designing the weight vectors of two-stage beamformers, the interference is completely canceled in the output of QSWL GSC and the desired signal is not distorted. We derive the array’s gain expression and analyze the performance of the QSWL GSC in the presence of one type of interference. The advantage of QSWL GSC is that the main beam can always point to the desired signal’s direction and the robustness to DOA mismatch is improved. Finally, simulations are used to verify the performance of the proposed QSWL GSC.

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Yang, Chen, Yang Jiao, Tingyi Jiang, Yiwen Xu, and Yaoyao Cui. "A United Sign Coherence Factor Beamformer for Coherent Plane-Wave Compounding with Improved Contrast." Applied Sciences 10, no. 7 (March 26, 2020): 2250. http://dx.doi.org/10.3390/app10072250.

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In this study, we present a united sign coherence factor beamformer for coherent plane-wave compounding (CPWC). CPWC is capable of reaching an image quality comparable to the conventional B-mode with a much higher frame rate. Conventional coherence factor (CF) based beamformers for CPWC are based on one-dimensional (1D) frameworks, either in the spatial coherence dimension or angular coherence dimension. Both 1D frameworks do not take into account the coherence information of the dimensions of each other. In order to take full advantage of the radio-frequency (RF) data, this paper proposes a united framework containing both spatial and angular information for CPWC. A united sign coherence factor beamformer (uSCF), which combines the conventional sign coherence factor (SCF) and the united framework, is introduced in the paper as well. The proposed beamformer is compared with the conventional 1D SCF beamformers (spatial and angular dimension beamformers) using simulation, phantom and in vivo studies. In the in vivo images, the proposed method improves the contrast ratio (CR) and generalized contrast-to-noise ratio (gCNR) by 197% and 20% over CPWC. Compared with other 1D methods, uSCF also shows an improved contrast and lateral resolution on all datasets.

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Ahmad, Zeeshan, Zain ul Abidin Jaffri, Najam ul Hassan, and Meng Chen. "Robust adaptive beamforming using modified constant modulus algorithms." Journal of Electrical Engineering 73, no. 4 (August 1, 2022): 248–57. http://dx.doi.org/10.2478/jee-2022-0033.

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Abstract This paper addresses the self-nulling phenomenon also known as the self-cancellation in adaptive beamformers. Optimum beamforming requires knowledge of the desired signal characteristics, either its statistics, its direction-of-arrival, or its response vector. Inaccuracies in the required information lead the beamformer to attenuate the desired signal as if it were interference. Self-nulling is caused by the desired signal having large power (high SNR) relative to the interference signal in case of the minimum variance distortion less response beamformer, and low power desired signal in the case of the constant modulus algorithm (CMA) beamformer, which leads the beamformer to suppress the desired signal and lock onto the interference signal. The least-square constant modulus algorithm is a prominent blind adaptive beamforming algorithm. We propose two CMA-based algorithms which exploit the constant modularity as well as power or DOA of the desired signal to avoid self-nulling in beamforming. Simulations results verify the effectiveness of the proposed algorithms.

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Buck, John R., Kathleen E. Wage, and Andrew C. Singer. "Are universal beamformers passive cognitive sonar systems?" Journal of the Acoustical Society of America 151, no. 4 (April 2022): A101. http://dx.doi.org/10.1121/10.0010787.

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Cognitive sonars dynamically tune system parameters to improve performance in pursuit of specific goals. Most research on cognitive sonar focuses on active sonar, varying the transmitted waveform and ping rate. Although passive sonar also faces the challenges of pursuing goals in varying and unknown environments, little research has been done exploring cognitive approaches to passive beamforming for sonar arrays. Universal beamformers provide one implementation of a cognitive approach to passive sonar. Practical adaptive beamformers generally regularize the sample covariance matrix before estimating the array weights. Universal beamformers blend the array weights across a family of beamformers competing on different choices for the regularization parameters. The blend of array weights is performance driven based, including the largest portion from the beamformers best suited for the current environment. Universal are “doubly adaptive” in that each competing beamformer is adapting its array weight vector in response to the data observed at the sensor array, the universal algorithm is then meta-adapting the blend of these array weight vectors used to process the data based on the performance of each competing beamformer. We will present examples of beamformers, which are universal over dominant subspace dimension and beam pattern notch width for moving interferers. [Work supported by ONR 321US.]

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Xie, Wupeng, Xiaoxiao Xiang, Xiaojuan Zhang, and Guanghong Liu. "A Pre-Separation and All-Neural Beamformer Framework for Multi-Channel Speech Separation." Symmetry 15, no. 2 (January 17, 2023): 261. http://dx.doi.org/10.3390/sym15020261.

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Thanks to the use of deep neural networks (DNNs), microphone array speech separation methods have achieved impressive performance. However, most existing neural beamforming methods explicitly follow traditional beamformer formulas, which possibly causes sub-optimal performance. In this study, a pre-separation and all-neural beamformer framework is proposed for multi-channel speech separation without following the solutions of the conventional beamformers, such as the minimum variance distortionless response (MVDR) beamformer. More specifically, the proposed framework includes two modules, namely the pre-separation module and the all-neural beamforming module. The pre-separation module is used to obtain pre-separated speech and interference, which are further utilized by the all-neural beamforming module to obtain frame-level beamforming weights without computing the spatial covariance matrices. The evaluation results of the multi-channel speech separation tasks, including speech enhancement subtasks and speaker separation subtasks, demonstrate that the proposed method is more effective than several advanced baselines. Furthermore, this method can be used for symmetrical stereo speech.

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Rahaman, Imteaz, Md Ashraful Haque, Narinderjit Singh Sawaran Singh, Md Shakiul Jafor, Pallab Kumar Sarkar, Md Afzalur Rahman, Mohd Azman Zakariya, Ghulam E. Mustafa Abro, and Nayan Sarker. "Performance Analysis of Linearly Arranged Concentric Circular Antenna Array with Low Sidelobe Level and Beamwidth Using Robust Tapering Technique." Micromachines 13, no. 11 (November 11, 2022): 1959. http://dx.doi.org/10.3390/mi13111959.

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In this research, a novel antenna array named Linearly arranged Concentric Circular Antenna Array (LCCAA) is proposed, concerning lower beamwidth, lower sidelobe level, sharp ability to detect false signals, and impressive SINR performance. The performance of the proposed LCCAA beamformer is compared with geometrically identical existing beamformers using the conventional technique where the LCCAA beamformer shows the lowest beamwidth and sidelobe level (SLL) of 12.50° and −15.17 dB with equal elements accordingly. However, the performance is degraded due to look direction error, for which robust techniques, fixed diagonal loading (FDL), optimal diagonal loading (ODL), and variable diagonal loading (VDL), are applied to all the potential arrays to minimize this problem. Furthermore, the LCCAA beamformer is further simulated to reduce the sidelobe applying tapering techniques where the Hamming window shows the best performance having 17.097 dB less sidelobe level compared to the uniform window. The proposed structure is also analyzed under a robust tapered (VDL-Hamming) method which reduces around 69.92 dB and 48.39 dB more sidelobe level compared to conventional and robust techniques. Analyzing all the performances, it is clear that the proposed LCCAA beamformer is superior and provides the best performance with the proposed robust tapered (VDL-Hamming) technique.

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Green, Tim, Gaston Hilkhuysen, Mark Huckvale, Stuart Rosen, Mike Brookes, Alastair Moore, Patrick Naylor, Leo Lightburn, and Wei Xue. "Speech recognition with a hearing-aid processing scheme combining beamforming with mask-informed speech enhancement." Trends in Hearing 26 (January 2022): 233121652110686. http://dx.doi.org/10.1177/23312165211068629.

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A signal processing approach combining beamforming with mask-informed speech enhancement was assessed by measuring sentence recognition in listeners with mild-to-moderate hearing impairment in adverse listening conditions that simulated the output of behind-the-ear hearing aids in a noisy classroom. Two types of beamforming were compared: binaural, with the two microphones of each aid treated as a single array, and bilateral, where independent left and right beamformers were derived. Binaural beamforming produces a narrower beam, maximising improvement in signal-to-noise ratio (SNR), but eliminates the spatial diversity that is preserved in bilateral beamforming. Each beamformer type was optimised for the true target position and implemented with and without additional speech enhancement in which spectral features extracted from the beamformer output were passed to a deep neural network trained to identify time-frequency regions dominated by target speech. Additional conditions comprising binaural beamforming combined with speech enhancement implemented using Wiener filtering or modulation-domain Kalman filtering were tested in normally-hearing (NH) listeners. Both beamformer types gave substantial improvements relative to no processing, with significantly greater benefit for binaural beamforming. Performance with additional mask-informed enhancement was poorer than with beamforming alone, for both beamformer types and both listener groups. In NH listeners the addition of mask-informed enhancement produced significantly poorer performance than both other forms of enhancement, neither of which differed from the beamformer alone. In summary, the additional improvement in SNR provided by binaural beamforming appeared to outweigh loss of spatial information, while speech understanding was not further improved by the mask-informed enhancement method implemented here.

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Belardinelli, Paolo, Erick Ortiz, and Christoph Braun. "Source Activity Correlation Effects on LCMV Beamformers in a Realistic Measurement Environment." Computational and Mathematical Methods in Medicine 2012 (2012): 1–8. http://dx.doi.org/10.1155/2012/190513.

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In EEG and MEG studies on brain functional connectivity and source interactions can be performed at sensor or source level. Beamformers are well-established source-localization tools for MEG/EEG signals, being employed in source connectivity studies both in time and frequency domain. However, it has been demonstrated that beamformers suffer from a localization bias due to correlation between source time courses. This phenomenon has been ascertained by means of theoretical proofs and simulations. Nonetheless, the impact of correlated sources on localization outputs with real data has been disputed for a long time. In this paper, by means of a phantom, we address the correlation issue in a realistic MEG environment. Localization performances in the presence of simultaneously active sources are studied as a function of correlation degree and distance between sources. A linear constrained minimum variance (LCMV) beamformer is applied to the oscillating signals generated by the current dipoles within the phantom. Results show that high correlation affects mostly dipoles placed at small distances (1, 5 centimeters). In this case the sources merge. If the dipoles lie 3 centimeters apart, the beamformer localization detects attenuated power amplitudes and blurred sources as the correlation level raises.

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Panea, Ionelia, and Guy Drijkoningen. "The spatial data-adaptive minimum-variance distortionless-response beamformer on seismic single-sensor data." GEOPHYSICS 73, no. 5 (September 2008): Q29—Q42. http://dx.doi.org/10.1190/1.2969058.

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Coherent noise generated by surface waves or ground roll within a heterogeneous near surface is a major problem in land seismic data. Array forming based on single-sensor recordings might reduce such noise more robustly than conventional hardwired arrays. We use the minimum-variance distortionless-response (MVDR) beamformer to remove (aliased) surface-wave energy from single-sensor data. This beamformer is data adaptive and robust when the presumed and actual desired signals are mismatched. We compute the intertrace covariance for the desired signal, and then for the total signal (desired [Formula: see text]) to obtain optimal weights. We use the raw data of only one array for the covariance of the total signal, and the wavenumber-filtered version of a full seismic single-sensor record for the covariance of the desired signal. In the determination of optimal weights, a parameter that controls the robustness of the beamformer against an arbitrary desired signal mismatch has to be chosen so that the results are optimal. This is similar to stabilization in deconvolution problems. This parameter needs to be smaller than the largest eigenvalue provided by the singular value decomposition of the presumed desired signal covariance. We compare results of MVDR beamforming with standard array forming on single-sensor synthetic and field seismic data. We apply 2D and 3D beamforming and show prestack and poststack results. MVDR beamformers are superior to conventional hardwired arrays for all examples.

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Won, Rachel. "Bessel beamformer." Nature Photonics 9, no. 3 (February 27, 2015): 141. http://dx.doi.org/10.1038/nphoton.2015.32.

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Bojja Venkatakrishnan, Satheesh, Elias A. Alwan, and John L. Volakis. "Challenges in Clock Synchronization for On-Site Coding Digital Beamformer." International Journal of Reconfigurable Computing 2017 (2017): 1–8. http://dx.doi.org/10.1155/2017/7802735.

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Typical radio frequency (RF) digital beamformers can be highly complex. In addition to a suitable antenna array, they require numerous receiver chains, demodulators, data converter arrays, and digital signal processors. To recover and reconstruct the received signal, synchronization is required since the analog-to-digital converters (ADCs), digital-to-analog converters (DACs), field programmable gate arrays (FPGAs), and local oscillators are all clocked at different frequencies. In this article, we present a clock synchronization topology for a multichannel on-site coding receiver (OSCR) using the FPGA as a master clock to drive all RF blocks. This approach reduces synchronization errors by a factor of 8, when compared to conventional digital beamformer.

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Abdalla, Ahmed, Suhad Mohammed, Abdelazeim Abdalla, Tang Bin, and Mohammed Ramadan. "A Study of a various Acoustic Beamforming Techniques Using a Microphone Array." Journal of Communications Technology, Electronics and Computer Science 1 (October 22, 2015): 7. http://dx.doi.org/10.22385/jctecs.v1i0.3.

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In this paper, A study of numerous acoustic beamforming algorithms is carried out. Beamforming algorithms are techniques utilize to determine the Direction of arrival of (DOA) the speech signals while suppress out the corresponding noises and interferences. The simple delay and sum beamformer technique which use the constrained least mean squares (LMS) filter for spatial filtering is firstly investigated. Secondly, a constrained least mean square algorithm (also known as Frost Beamformer) is considered. The beamformer algorithms are simulated in MATLAB and therefore, the simulation results indicate that there a significant enhancement in the Signal-to-Noise-Ratio (SNR) for frost beamformer as compared to the simple delay and sum beamformer.

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Ammothum Kandy, Parvathi, and Sakthivel Vellaisamy. "Design of Sparse Uniform Linear Array Beamformer using Modified FRM Structure for Varied Applications." International journal of electrical and computer engineering systems 13, no. 8 (November 10, 2022): 695–700. http://dx.doi.org/10.32985/ijeces.13.8.9.

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This paper presents a method to generate antenna patterns for a Uniform Linear Array (ULA) having narrow beamwidth and low sidelobe levels (SLL) using the recently proposed Modified FRM (ModFRM) architecture. This allows it to direct the beams to specific ground cells for communications while mitigating inter-cell interference. The sharpness of the beam pattern defines the spatial discriminating performance of a ULA beamformer, while the SLL dictates the interference and noise suppression capabilities. Typically, a conventional ULA beamforming will demand high computational complexity and a large number of sensors to satisfy these requirements. Hence to reduce the system cost, using the ModFRM technique a sparse array is developed. With this strategy, the total number of sensors is drastically reduced compared to conventional ULA beamformers. The designed beamformers can be used in applications with stringent requirements where cost and size are concerned.

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Zhang, Junpeng, and Dezhong Yao. "IMPROVED BEAMFORMER WITH WEIGHTED SOURCE REGION SUPPRESSION FOR COHERENT MEG SOURCE LOCALIZATION." Biomedical Engineering: Applications, Basis and Communications 22, no. 03 (June 2010): 239–48. http://dx.doi.org/10.4015/s1016237210001955.

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Beamformer is one of the main techniques for spatio-temporal neuroelectromagnetic source reconstruction. However, the classical Beamformer is extremely sensitive to strongly coherent sources, thereby encountering difficulty in localizing the highly correlated bilateral auditory cortices in auditory evoked field (AEF) or auditory steady state evoked potential. The multiple constrained minimum-variance Beamformer with coherent source region suppression (Beamformer-CS) can potentially overcome such difficulties. However, when coherent interferer is located close to the edges of the suppression region, Beamformer-CS has localization bias and the closer it is, the larger it will be. Here, we present an improved Beamformer-CS that can localize coherent sources with much less localization bias, especially in the case of the interferer close to the edges of the suppression region. First, based on approximate information about source energy distribution from other neuroimaging techniques, a region encompassing the coherent interfering sources is defined. Then, the dominant eigenvectors of the lead field matrix, weighted using source energy information obtained by other imaging method, for the suppression region is incorporated into Beamformer design as hard null constraints. Such weighting strategy is able to improve the localization performance. Simulation test shows that, compared to Beamformer-CS, the new weighting approach is of much smaller localization bias, sharper peak of the estimated sources, more robust against noise, and less sensitiveness to the number of the eigenvector components for the suppression region, as is also confirmed by real AEF data test.

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Aspell, Elizabeth, Erin Picou, and Todd Ricketts. "Directional Benefit Is Present with Audiovisual Stimuli: Limiting Ceiling Effects." Journal of the American Academy of Audiology 25, no. 07 (July 2014): 666–75. http://dx.doi.org/10.3766/jaaa.25.7.5.

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Background: Past research demonstrates that as the speech recognition performance of listeners fitted with omnidirectional hearing aids approaches maximum (ceiling), the benefit afforded by directional microphones is necessarily lessened. This effect could potentially eliminate the benefit provided by directional microphones in easier listening situations, such as environments with visual cues and favorable signal-to-noise ratios (SNRs). Purpose: The purpose of this study was to evaluate directional benefit using auditory-visual stimuli in SNRs commonly found in the real world (ranging from +3 to +12 dB). In order to maximize the possibility of directional benefit, a bilateral beamformer was used, which functions as a highly directional microphone. Research Design: Sentence recognition was evaluated in three SNRs and in two levels of reverberation (low and moderate). For each SNR and reverberation combination, sentence recognition was evaluated using omnidirectional and bilateral beamformer microphone modes. Study Sample: A total of 15 adults with hearing loss participated. Only listeners who had significant difficulty understanding speech in noise were included. Data Collection and Analysis: Sentence recognition scores were evaluated using analysis of variance with three within-participant variables (SNR, reverb, microphone mode). Follow-up analyses were conducted using linear contrast while controlling for family-wise error rate. Results: Results revealed significant bilateral beamformer benefit ranging from approximately 22–30 rationalized arcsine units (˜20–28 percentage points) in both low and moderate reverberation across all tested SNRs (+3 to +12 dB). Conclusions: These results provide support for the use of bilateral beamformers, even at relatively favorable SNRs and in the presence of visual cues, for listeners who demonstrate poor sentence recognition in noise.

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Hládek, Ĺuboš, Bernd Porr, Graham Naylor, Thomas Lunner, and W. Owen Brimijoin. "On the Interaction of Head and Gaze Control With Acoustic Beam Width of a Simulated Beamformer in a Two-Talker Scenario." Trends in Hearing 23 (January 2019): 233121651987679. http://dx.doi.org/10.1177/2331216519876795.

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Superdirectional acoustic beamforming technology provides a high signal-to-noise ratio, but potential speech intelligibility benefits to hearing aid users are limited by the way the users move their heads. Steering the beamformer using eye gaze instead of head orientation could mitigate this problem. This study investigated the intelligibility of target speech with a dynamically changing direction when heard through gaze-controlled (GAZE) or head-controlled (HEAD) superdirectional simulated beamformers. The beamformer provided frequency-independent noise attenuation of either 8 dB (WIDE [moderately directional]) or 12 dB (NARROW [highly directional]) relative to no beamformer referred as the OMNI (omni-directional) condition. Before the main experiment, signal-to-noise ratios were normalized for each participant and each beam width condition to yield equal percentage of correct performance in a reference condition. Hence, results are presented as normalized speech intelligibility (NSI). In an ongoing presentation, the participants ( n = 17), of varying degree of hearing loss, heard single-word targets every 1.5 s coming from either left (−30°) or right (+30°) presented in continuous, spatially distributed, speech-shaped noise. When the target was static, NSI was better in the GAZE than in the HEAD condition, but only when the beam was NARROW. When the target switched location without warning, NSI performance dropped. In this case, the WIDE HEAD condition provided the best average NSI performance, because some participants tended to orient their head in between the targets, allowing them to hear out the target regardless of location. The difference in NSI between GAZE and HEAD conditions for individual participants was related to the observed head-orientation strategy, which varied widely across participants.

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Singh, Satyanand, Sajai Vir Singh, Dinesh Yadav, Sanjay Kumar Suman, Bhagyalakshmi Lakshminarayanan, and Ghanshyam Singh. "Discrete interferences optimum beamformer in correlated signal and interfering noise." International Journal of Electrical and Computer Engineering (IJECE) 12, no. 2 (April 1, 2022): 1732. http://dx.doi.org/10.11591/ijece.v12i2.pp1732-1743.

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This paper introduces a significant special situation where the noise is a collection of D-plane interference signals and the correlated noise of D+1 is less than the number of array components. An optimal beamforming processor based on the minimum variance distortionless response (MVDR) generates and combines appropriate statistics for the D+1 model. Instead of the original space of the N-dimensional problem, the interference signal subspace is reduced to D+1. Typical antenna arrays in many modern communication networks absorb waves generated from multiple point sources. An analytical formula was derived to improve the signal to interference and noise ratio (SINR) obtained from the steering errors of the two beamformers. The proposed MVDR processor-based beamforming does not enforce general constraints. Therefore, it can also be used in systems where the steering vector is compromised by gain. Simulation results show that the output of the proposed beamformer based on the MVDR processor is usually close to the ideal state within a wide range of signal-to-noise ratio and signal-to-interference ratio. The MVDR processor-based beamformer has been experimentally evaluated. The proposed processor-based MVDR system significantly improves performance for large interference white noise ratio (INR) in the sidelobe region and provide an appropriate beam pattern.

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Gou, Xiaoming, Zhiwen Liu, Jingyan Ma, and Yougen Xu. "User–Parameter–Free Robust Adaptive Beamforming Algorithm for Vector–Sensor Arrayswithin the Hypercomplex Framework." Journal of Electrical Engineering 64, no. 2 (March 1, 2013): 100–105. http://dx.doi.org/10.2478/jee-2013-0014.

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The major flaw of the conventional diagonal loading (DL) method is that it is unclear to choose appropriate DL levels or user-parameters (UPs), though several remarkable contributions have been made to regularize model errors without UPs. An UP-free algorithm for two-component vector-sensor arrays, which is robust to steering vector errors, is considered. The algorithm is within the hypercomplex framework using quaternions, and the optimal solution is found at the maximal correlation between the quaternionic and complex outputs. The performance of the proposed beamformer is illustrated via numerical simulations and is compared with several other UP-free adaptive beamformers

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Chu, Yi, Wei Yau Horng, Shinn Fwu Wang, Shyh Rong Lay, and Yu Pin Liao. "Pseudo-Interference Technique for Reducing the Mutual Coupling Effects in Adaptive Beamformers." Applied Mechanics and Materials 427-429 (September 2013): 2054–58. http://dx.doi.org/10.4028/www.scientific.net/amm.427-429.2054.

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A robust beamformer with pseudo-interference approach for reducing the effect of mutual coupling is present in this paper. This technique uses injected interference to improve the equivalent interference-to-noise ratio in the diagonally loaded Capon beamformer. The mutual coupling coefficients are estimated for interference correlation matrix reconstruction. The resulted beamformer is insensitive to the mutual coupling effects and angular mismatch.

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Li, Hongtao, Zhoupeng Ding, Sirui Tian, and Songpo Jin. "Robust Adaptive Transmit Beamforming under the Constraint of Low Peak-to-Average Ratio." Sensors 22, no. 19 (September 26, 2022): 7278. http://dx.doi.org/10.3390/s22197278.

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In radar detection, in order to make the beam have variable directivity, a Capon beamformer is usually used. Although this traditional beamformer enjoys both high resolution and good interference suppression, it usually leads to high sidelobe and is sensitive to array steering vector (ASV) mismatch. To overcome such problems, this study devises a novel, robust adaptive beamformer that is robust to ASV mismatch under the constraint where the sidelobe is oriented to the ground. Moreover, to make full use of the transmit power, the constraint of a low peak-to-average power ratio (PAPR) is also taken into consideration. Accordingly, this robust adaptive beamformer is developed by optimizing a transmitting beamformer constrained by ASV mismatch and low PAPR. This optimization problem is transformed into a second-order cone programming (SOCP) problem which can be efficiently and exactly solved. The proposed transmit beamformer possesses not only adaptive interference rejection ability and robustness against ASV mismatch, but also direct sidelobe control and a low PAPR. Simulation results are presented to demonstrate the superiority of the proposed approach. The proposed method can make the peak sidelobe level (PSL) level on the ground side below −30 dB.

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Hong, Jun Hee, and Sung Chan Jun. "Scanning Reduction Strategy in MEG/EEG Beamformer Source Imaging." Journal of Applied Mathematics 2012 (2012): 1–19. http://dx.doi.org/10.1155/2012/528469.

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MEG/EEG beamformer source imaging is a promising approach which can easily address spatiotemporal multi-dipole problems without a priori information on the number of sources and is robust to noise. Despite such promise, beamformer generally has weakness which is degrading localization performance for correlated sources and is requiring of dense scanning for covering all possible interesting (entire) source areas. Wide source space scanning yields all interesting area images, and it results in lengthy computation time. Therefore, an efficient source space scanning strategy would be beneficial in achieving accelerated beamformer source imaging. We propose a new strategy in computing beamformer to reduce scanning points and still maintain effective accuracy (good spatial resolution). This new strategy uses the distribution of correlation values between measurements and lead-field vectors. Scanning source points are chosen yielding higher RMS correlations than the predetermined correlation thresholds. We discuss how correlation thresholds depend on SNR and verify the feasibility and efficacy of our proposed strategy to improve the beamformer through numerical and empirical experiments. Our proposed strategy could in time accelerate the conventional beamformer up to over 40% without sacrificing spatial accuracy.

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Melis, A., R. Chiello, G. Comoretto, R. Concu, A. Magro, G. Naldi, A. Navarrini, et al. "A Digital Beamformer for the PHAROS2 Phased Array Feed." Journal of Astronomical Instrumentation 09, no. 03 (September 2020): 2050013. http://dx.doi.org/10.1142/s2251171720500130.

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PHased Arrays for Reflector Observing Systems (PHAROS) is a C-band (4–8[Formula: see text]GHz) Phased Array Feed (PAF) receiver designed to operate from the primary focus of a large single-dish radio astronomy antenna. It consists of an array of 220-element Vivaldi antennas ([Formula: see text] polarization), cryogenically cooled at roughly 20[Formula: see text]K along with low noise amplifiers (LNAs), and of analogue beamformers cryogenically cooled at roughly 80[Formula: see text]K. PHAROS2, the upgrade of PHAROS, is a PAF demonstrator developed in the framework of the Square Kilometer Array Advanced Instrumentation Program (SKA AIP) with the goal of investigating the potential of the PAF technologies at high frequencies in view of their possible application on the SKA dish telescopes. The PHAROS2 design includes new cryogenically cooled LNAs with state-of-the-art performance, a digital beamformer capable of synthesizing four beams from a sub-array of 24 single-polarization antenna elements, and a C-band multi-channel Warm Section receiver capable of analogue filtering and down-converting the signals from the antennas to a suitable frequency range at the input of the digital backend, providing an instantaneous bandwidth of 275[Formula: see text]MHz for each signal. In this paper, we describe the design and performance of the PHAROS2 digital backend/beamformer, based on the Italian Tile Processing Module (ITPM) hardware, which was initially developed for the SKA Low Frequency Aperture Array (LFAA). The backend was adapted to perform the beamforming for our PAF application. We describe the implementation of the beamformer on the Field Programmable Gate Arrays (FPGAs) of the ITPM and how the backend was successfully used to synthesize four independent beams, both in the laboratory (across the entire 275[Formula: see text]MHz instantaneous bandwidth) and during on-field observations at the BEST-2 array (across 16[Formula: see text]MHz instantaneous bandwidth), which is a subset of the Northern Cross Radio Telescope (located in the district of Bologna, Italy). The beamformer design allows re-scaling to a greater number of beams and wider bandwidths.

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Zhang, Tao, and Liguo Sun. "Iterative Robust Capon Beamforming with Adaptively Updated Array Steering Vector Mismatch Levels." International Scholarly Research Notices 2014 (November 3, 2014): 1–8. http://dx.doi.org/10.1155/2014/260875.

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The performance of the conventional adaptive beamformer is sensitive to the array steering vector (ASV) mismatch. And the output signal-to interference and noise ratio (SINR) suffers deterioration, especially in the presence of large direction of arrival (DOA) error. To improve the robustness of traditional approach, we propose a new approach to iteratively search the ASV of the desired signal based on the robust capon beamformer (RCB) with adaptively updated uncertainty levels, which are derived in the form of quadratically constrained quadratic programming (QCQP) problem based on the subspace projection theory. The estimated levels in this iterative beamformer present the trend of decreasing. Additionally, other array imperfections also degrade the performance of beamformer in practice. To cover several kinds of mismatches together, the adaptive flat ellipsoid models are introduced in our method as tight as possible. In the simulations, our beamformer is compared with other methods and its excellent performance is demonstrated via the numerical examples.

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Ortolan, L., T. L. S. Santos, M. C. F. DeCastro, and F. C. C. DeCastro. "Blind concurrent beamformer." Electronics Letters 43, no. 1 (2007): 5. http://dx.doi.org/10.1049/el:20072759.

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Hasegawa, Hideyuki. "Apodized adaptive beamformer." Journal of Medical Ultrasonics 44, no. 2 (January 13, 2017): 155–65. http://dx.doi.org/10.1007/s10396-016-0764-3.

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Han, Shuo, Yunkai Deng, Wei Wang, Qingchao Zhao, Jinsong Qiu, Yongwei Zhang, and Zhen Chen. "A Novel Echo Separation Scheme for Space-Time Waveform-Encoding SAR Based on the Second-Order Cone Programming (SOCP) Beamformer." Remote Sensing 14, no. 22 (November 20, 2022): 5888. http://dx.doi.org/10.3390/rs14225888.

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Space-time waveform-encoding (STWE)-synthetic aperture radar (SAR) is an effective way to accomplish high-resolution and wide-swath (HRWS) imaging. By designing the specific signal transmit mode, the echoes from several subswaths are received within a single receiving window and overlap each other in STWE-SAR. In order to separate the overlapped echoes, the linear-constrained minimum variance (LCMV) beamformer, a single-null beamformer, is typically used. However, the LCMV beamformer has a very narrow and unstable notch depth, which is not sufficient to accurately separate the overlapped echoes with large signal energy differences between subswaths. The issue of signal energy differences in STWE-SAR is first raised in this paper. Moreover, a novel echo separation scheme based on a second-order cone programming (SOCP) beamformer is proposed. The beam pattern generated by the SOCP beamformer allows flexible adjustment of the notch width and depth, which effectively improves the quality of separation results compared to the LCMV beamformer. The simulation results illustrate that the scheme can greatly enhance the performance of echo separation. Furthermore, the experimental results based on the X-band STWE-SAR airborne system not only demonstrate the scheme’s effectiveness but also indicate that it holds great promise for future STWE-SAR missions.

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S, Siva Priyanka, and Kishore Kumar T. "Signed Convex Combination of Fast Convergence Algorithm to Generalized Sidelobe Canceller Beamformer for Multi-Channel Speech Enhancement." Traitement du Signal 38, no. 3 (June 30, 2021): 785–95. http://dx.doi.org/10.18280/ts.380325.

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In speech communication applications such as teleconferences, mobile phones, etc., the real-time noises degrade the desired speech quality and intelligibility. For these applications, in the case of multichannel speech enhancement, the adaptive beamforming algorithms play a major role compared to fixed beamforming algorithms. Among the adaptive beamformers, Generalized Sidelobe Canceller (GSC) beamforming with Least Mean Square (LMS) Algorithm has the least complexity but provides poor noise reduction whereas GSC beamforming with Combined LMS (CLMS) algorithm has better noise reduction performance but with high computational complexity. In order to achieve a tradeoff between noise reduction and computational complexity in real-time noisy conditions, a Signed Convex Combination of Fast Convergence (SCCFC) algorithm based GSC beamforming for multi-channel speech enhancement is proposed. This proposed SCCFC algorithm is implemented using a signed convex combination of two Fast Convergence Normalized Least Mean Square (FCNLMS) adaptive filters with different step-sizes. This improves the overall performance of the GSC beamformer in real-time noisy conditions as well as reduces the computation complexity when compared to the existing GSC algorithms. The performance of the proposed multi-channel speech enhancement system is evaluated using the standard speech processing performance metrics. The simulation results demonstrate the superiority of the proposed GSC-SCCFC beamformer over the traditional methods.

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Ye-Cai, Guo, Wang Chao, and Zhang Ning. "Robust Nearfield Wideband Beamforming Design Based on Adaptive-Weighted Convex Optimization." Mathematical Problems in Engineering 2017 (2017): 1–10. http://dx.doi.org/10.1155/2017/5124059.

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Nearfield wideband beamformers for microphone arrays have wide applications in multichannel speech enhancement. The nearfield wideband beamformer design based on convex optimization is one of the typical representatives of robust approaches. However, in this approach, the coefficient of convex optimization is a constant, which has not used all the freedom provided by the weighting coefficient efficiently. Therefore, it is still necessary to further improve the performance. To solve this problem, we developed a robust nearfield wideband beamformer design approach based on adaptive-weighted convex optimization. The proposed approach defines an adaptive-weighted function by the adaptive array signal processing theory and adjusts its value flexibly, which has improved the beamforming performance. During each process of the adaptive updating of the weighting function, the convex optimization problem can be formulated as a SOCP (Second-Order Cone Program) problem, which could be solved efficiently using the well-established interior-point methods. This method is suitable for the case where the sound source is in the nearfield range, can work well in the presence of microphone mismatches, and is applicable to arbitrary array geometries. Several design examples are presented to verify the effectiveness of the proposed approach and the correctness of the theoretical analysis.

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Pato, Matilde, Ricardo Eleutério, Raquel C. Conceição, and Daniela M. Godinho. "Evaluating the Performance of Algorithms in Axillary Microwave Imaging towards Improved Breast Cancer Staging." Sensors 23, no. 3 (January 29, 2023): 1496. http://dx.doi.org/10.3390/s23031496.

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Breast cancer is the most common and the fifth deadliest cancer worldwide. In more advanced stages of cancer, cancer cells metastasize through lymphatic and blood vessels. Currently there is no satisfactory neoadjuvant (i.e., preoperative) diagnosis to assess whether cancer has spread to neighboring Axillary Lymph Nodes (ALN). This paper addresses the use of radar Microwave Imaging (MWI) to detect and determine whether ALNs have been metastasized, presenting an analysis of the performance of different artifact removal and beamformer algorithms in distinct anatomical scenarios. We assess distinct axillary region models and the effect of varying the shape of the skin, muscle and subcutaneous adipose tissue layers on single ALN detection. We also study multiple ALN detection and contrast between healthy and metastasized ALNs. We propose a new beamformer algorithm denominated Channel-Ranked Delay-Multiply-And-Sum (CR-DMAS), which allows the successful detection of ALNs in order to achieve better Signal-to-Clutter Ratio, e.g., with the muscle layer up to 3.07 dB, a Signal-to-Mean Ratio of up to 20.78 dB and a Location Error of 1.58 mm. In multiple target detection, CR-DMAS outperformed other well established beamformers used in the context of breast MWI. Overall, this work provides new insights into the performance of algorithms in axillary MWI.

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Du, Rui, Yangyu Fan, and Jianshu Wang. "Design of Fixed Wideband Beamformer through Improved Maximum Energy Approach." Journal of Electrical and Computer Engineering 2016 (2016): 1–7. http://dx.doi.org/10.1155/2016/7912364.

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A maximum energy approach is investigated in this paper to design fixed wideband beamformer. This approach has been improved by integrating response variation (RV) into the target function to maintain the frequency invariant property of wideband beamformer over the whole passband. Two methods for designing null to suppress interference signal also have been proposed to make the wideband beamformer robust in complicated environment. Comparisons among other methods are provided to illustrate the effectiveness and enhancement of performance of the new approaches.

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Mizumachi, Mitsunori, and Ryotarou Oka. "Non-linear beamformer with long short-term memory network." INTER-NOISE and NOISE-CON Congress and Conference Proceedings 263, no. 2 (August 1, 2021): 4355–60. http://dx.doi.org/10.3397/in-2021-2673.

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Acoustic beamforming with a microphone array enables spatial filtering in a wide frequency range. It is a challenging issue to sharpen the main-lobe in the lower frequency region with a small-scale microphone array, of which the number and spacing of microphones are small. A neural network-based non-linear beamformer achieves a breakthrough in sharpening the main-lobe. The non-linear beamforming works well for the narrowband signals but is weak in wideband beamforming. The non-linear beamforming with the long short-term memory is proposed to deal with wideband speech signals. The long short-term memory network is trained in the recurrent neural network architecture with the sequence of audio data such as speech signals. The performance of the proposed beamformer is confirmed using a small-scale 8-ch MEMS microphone array, where eight microphones are linearly arranged with the neighboring spacing of 10 mm, under a real environment. The beam-pattern of the proposed non-linear beamformer succeeds in sharpening the main-lobe although the linear delay-and-sum beamformer could not achieve frequency selectivity. The feasibility of the proposed beamformer is also confirmed in speech enhancement.

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Albagory, Yasser, and Fahad Alraddady. "An Efficient Recursive Multibeam Pattern Subtraction (MPS) Beamformer for Planar Antenna Arrays Optimization." Electronics 11, no. 7 (March 24, 2022): 1015. http://dx.doi.org/10.3390/electronics11071015.

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In this paper, a new beamforming technique for planar two-dimensional arrays is proposed for optimizing the sidelobe levels (SLLs) by using recursive multibeam pattern subtraction (MPS) technique. The proposed MPS beamformer is demonstrated and its convergence to lower SLL values is investigated and controlled. The performance analysis has shown that the proposed MPS beamformer can effectively reduce the SLL down to less than −50 dB relative to the mainlobe level utilizing the major sidelobes information in the radiation pattern. In addition, the proposed MPS beamformer can be applied to any planar array geometry such as rounded corners rectangular arrays provided that the original array pattern contains sidelobe peaks. The comparison with recent related techniques has shown that the proposed beamformer provides faster convergence time. On the other hand, the proposed technique provides lower sidelobe levels which cannot be achieved by efficient tapering windows for planar two-dimensional arrays. Finally, the scanning performance of the proposed MPS beamformer is demonstrated and the simulation results show solid and consistent SLL levels over the whole angular range from the broadside to endfire directions of the array.

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Rahaman, Imteaz, Md Shakiul Jafor, Narinderjit Singh Sawaran Singh, Md Ashraful Haque, Antar Kumar Biswas, Md Afzalur Rahman, M. Azman B. Zakariya, Ghulam E. Mustafa Abro, and Nayan Sarker. "Performance Investigation of Linearly Arranged Circular, Circular Planer, Rectangular, and Concentric Circular Antenna Arrays Using Robust NVL Techniques." Applied Sciences 12, no. 22 (November 11, 2022): 11481. http://dx.doi.org/10.3390/app122211481.

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In this research, linearly arranged circular antenna array (LCAA), linearly arranged circular planer antenna array (LCPAA), linearly arranged rectangular antenna array (LRAA), and linearly arranged concentric circular antenna array (LCCAA) are analyzed using robust techniques. These four antenna arrays are briefly investigated to evaluate their beam width performance, ability to detect a false signal, and SINR power pattern performances. Robust techniques—fixed diagonal loading (FDL), optimal diagonal loading (ODL), variable diagonal loading (VDL), and new variable loading (NVL) techniques—are applied, and the NVL technique is found to be superior and provides the best performance with the proposed LCCAA beamformer. With an SINR of 40.45 dB, 40.29 dB, 40.18 dB, and 39.99 dB for 0°, 1°, 2°, and 3° disparity angles, respectively, and output powers of −0.019 dB, −0.076 dB, and −0.171 dB for 1°, 2°, and 3° disparity angles, respectively, LCCAA beamformers using the NVL technique outperform other beamformers with different robust approaches.

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Wang, Ping, Jiaqi Liang, and Xitao Li. "Depth-dependent apodization window based on Chebyshev polynomial for ultrasound imaging." Journal of the Acoustical Society of America 152, no. 1 (July 2022): 19–30. http://dx.doi.org/10.1121/10.0011917.

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To improve the image resolution of a portable real-time ultrasound imaging device, this paper proposes a beamformer with composite apodization windows based on Chebyshev polynomial. By introducing the Chebyshev window, the level of sidelobe can be flexibly controlled. The value of weighting changes according to the detection depth and ultrasound attenuation such that it can attain better image resolution than traditional beamformers. The simulations and experiments indicate that the proposed method can flexibly narrow the mainlobe width while keeping the performance of the suppressing artifacts. The full width at half-maximum of this method is 14.1%–27.8% and 4.2%–25.0% narrower than those of traditional apodization methods in the field II simulations and Geabr_0 experiment, respectively.

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Guo, Yumei, Qiang Li, Linrang Zhang, Juan Zhang, and Zhanye Chen. "An Oblique Projection-Based Beamforming Method for Coherent Signals Receiving." Remote Sensing 14, no. 19 (October 9, 2022): 5043. http://dx.doi.org/10.3390/rs14195043.

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Within a complex sea or ground surface background, multipath signals are strongly correlated or even completely coherent, which leads to signal cancellation when conventional optimal beamforming is performed. Aiming at the above problem, a coherent signal-receiving algorithm is proposed based on oblique projection technology in this paper. The direction of arrival (DOA) of incident signals is estimated firstly by the space smoothing-based MUSIC method. The composite steering vector of multipath coherent signals is then obtained utilizing the oblique projection matrix constructed with the estimated angles. The weight vector is thereby derived with the minimum variance distortionless response criteria. The proposed oblique projection-based beamformer can receive the multipath coherent signals effectively. Moreover, the proposed beamformer is more robust and converges to optimal beamformer rapidly without aperture loss. The theoretical analysis and simulation verify the validity and superiority of the proposed coherent signal beamformer.

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Hwang, SungHwan, HanSaeng Kim, JaeHwan Lim, JoungMyoung Joo, KiWon Lee, MinSang Kwon, and Woo-Sung Kim. "Design of Real-Time Digital Multi-Beamformer of Digital Array Antenna System for MFR." Journal of the Korea Institute of Military Science and Technology 25, no. 2 (April 5, 2022): 151–59. http://dx.doi.org/10.9766/kimst.2022.25.2.151.

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In this paper, we implement a digital multi-beamformer using FPGA(Field Programmable Gate Array) which has advantages in parallel and real-time data processing. This is accomplished through the use of not only high-speed data communication but also multiple beam forming, which is currently required by MFR(Multi Function Radar). As a result, the beamformer can process 24 Gbps throughput in real-time and form 5 digital beams at the same time. It is also compared to the results of Matlab simulations. We demonstrate how an implemented beamformer can be used in an MFR system by using a digital array antenna.

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Tong, Luyen, and Cuong Nguyen. "An effective beamformer for interference suppression without knowing the direction." International Journal of Electrical and Computer Engineering (IJECE) 13, no. 1 (February 1, 2023): 601. http://dx.doi.org/10.11591/ijece.v13i1.pp601-610.

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<span>This paper proposes an effective beamformer for uniform linear arrays of half-wave dipole antennas based on binary bat algorithm (BBA) by controlling complex weights (both amplitudes and phases) excited at elements in an array. The proposed beamformer can impose adaptive nulls at interferences without knowing directions in the sidelobe region by minimizing the total output power of an array, whereas the main lobe and sidelobe levels are maintained. To demonstrate this capability, the proposal will be evaluated in several scenarios, compared to a beamformer based on binary particle swarm optimization (BPSO).</span>

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Yilmazer, Nuri, Wonsuk Choi, Tapan Sarkar, and Sunmeel Bhumkar. "Non-Statistical Multi-Beamformer." Journal of Signal and Information Processing 03, no. 01 (2012): 26–29. http://dx.doi.org/10.4236/jsip.2012.31003.

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Haugen, Geir Ultveit. "Ultrasound probe distributed beamformer." Journal of the Acoustical Society of America 126, no. 4 (2009): 2142. http://dx.doi.org/10.1121/1.3238228.

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Xie, Ning, Hui Wang, and Hongwei Liu. "Broadband Frequency Invariant Beamformer." Wireless Personal Communications 61, no. 1 (May 22, 2010): 143–59. http://dx.doi.org/10.1007/s11277-010-0015-7.

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Torras-Rosell, Antoni, Salvador Barrera-Figueroa, and Finn Jacobsen. "An acousto-optic beamformer." Journal of the Acoustical Society of America 132, no. 1 (July 2012): 144–49. http://dx.doi.org/10.1121/1.4726047.

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Monnai, Yasuaki, David Jahn, Withawat Withayachumnankul, Martin Koch, and Hiroyuki Shinoda. "Terahertz plasmonic Bessel beamformer." Applied Physics Letters 106, no. 2 (January 12, 2015): 021101. http://dx.doi.org/10.1063/1.4905445.

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Rubsamen, Michael, and Marius Pesavento. "Maximally Robust Capon Beamformer." IEEE Transactions on Signal Processing 61, no. 8 (April 2013): 2030–41. http://dx.doi.org/10.1109/tsp.2013.2242067.

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Sullivan, Edmund J. "Conformal array compensating beamformer." Journal of the Acoustical Society of America 77, no. 1 (January 1985): 337. http://dx.doi.org/10.1121/1.392114.

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Vrba, Jiri, Samu Taulu, Jukka Nenonen, and Antti Ahonen. "Signal Space Separation Beamformer." Brain Topography 23, no. 2 (November 27, 2009): 128–33. http://dx.doi.org/10.1007/s10548-009-0120-7.

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Komeylian, Somayeh, and Christopher Paolini. "Implementation of the Digital QS-SVM-Based Beamformer on an FPGA Platform." Sensors 23, no. 3 (February 3, 2023): 1742. http://dx.doi.org/10.3390/s23031742.

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To address practical challenges in establishing and maintaining robust wireless connectivity such as multi-path effects, low latency, size reduction, and high data rate, we have deployed the digital beamformer, as a spatial filter, by using the hybrid antenna array at an operating frequency of 10 GHz. The proposed digital beamformer utilizes a combination of the two well-established beamforming techniques of minimum variance distortionless response (MVDR) and linearly constrained minimum variance (LCMV). In this case, the MVDR beamforming method updates weight vectors on the FPGA board, while the LCMV beamforming technique performs nullsteering in directions of interference signals in the real environment. The most well-established machine learning technique of support vector machine (SVM) for the Direction of Arrival (DoA) estimation is limited to problems with linearly-separable datasets. To overcome the aforementioned constraint, the quadratic surface support vector machine (QS-SVM) classifier with a small regularizer has been used in the proposed beamformer for the DoA estimation in addition to the two beamforming techniques of LCMV and MVDR. In this work, we have assumed that five hybrid array antennas and three sources are available, at which one of the sources transmits the signal of interest. The QS-SVM-based beamformer has been deployed on the FPGA board for spatially filtering two signals from undesired directions and passing only one of the signals from the desired direction. The simulation results have verified the strong performance of the QS-SVM-based beamformer in suppressing interference signals, which are accompanied by placing deep nulls with powers less than −10 dB in directions of interference signals, and transferring the desired signal. Furthermore, we have verified that the performance of the QS-SVM-based beamformer yields other advantages including average latency time in the order of milliseconds, performance efficiency of more than 90%, and throughput of nearly 100%.

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Dorman, Michael F., Sarah Natale, Anthony Spahr, and Erin Castioni. "Speech Understanding in Noise by Patients With Cochlear Implants Using a Monaural Adaptive Beamformer." Journal of Speech, Language, and Hearing Research 60, no. 8 (August 18, 2017): 2360–63. http://dx.doi.org/10.1044/2017_jslhr-h-16-0312.

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Purpose The aim of this experiment was to compare, for patients with cochlear implants (CIs), the improvement for speech understanding in noise provided by a monaural adaptive beamformer and for two interventions that produced bilateral input (i.e., bilateral CIs and hearing preservation [HP] surgery). Method Speech understanding scores for sentences were obtained for 10 listeners fit with a single CI. The listeners were tested with and without beamformer activated in a “cocktail party” environment with spatially separated target and maskers. Data for 10 listeners with bilateral CIs and 8 listeners with HP CIs were taken from Loiselle, Dorman, Yost, Cook, and Gifford (2016), who used the same test protocol. Results The use of the beamformer resulted in a 31 percentage point improvement in performance; in bilateral CIs, an 18 percentage point improvement; and in HP CIs, a 20 percentage point improvement. Conclusion A monaural adaptive beamformer can produce an improvement in speech understanding in a complex noise environment that is equal to, or greater than, the improvement produced by bilateral CIs and HP surgery.

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Journal articles on the topic 'Beamformer'

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