Results 141 to 150 of about 10,533 (195)
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IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, 2017
Acoustically hard objects, such as bones, needles, or catheters, are poorly visualized in conventional ultrasound images. These objects behave like acoustic mirrors and reflect sound in specific directions. Soft tissue and diffusive reflectors scatter sound in a broad range of directions.
Alfonso Rodriguez-Molares +3 more
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Acoustically hard objects, such as bones, needles, or catheters, are poorly visualized in conventional ultrasound images. These objects behave like acoustic mirrors and reflect sound in specific directions. Soft tissue and diffusive reflectors scatter sound in a broad range of directions.
Alfonso Rodriguez-Molares +3 more
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Smooth Beamforming and Efficient Beamforming Weight Computation
IEEE GLOBECOM 2007-2007 IEEE Global Telecommunications Conference, 2007This paper investigates an efficient way of computing the beamforming weights for a MIMO OFDM system. It is shown that computing the weights incrementally across correlated channels can significantly reduce the complexity. An additional benefit of this technique is that it provides a "smooth" beamformer, i.e., it does not significantly change the ...
Magnus Sandell, Vishakan Ponnampalam
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Differential Beamforming on Graphs
IEEE/ACM Transactions on Audio, Speech, and Language Processing, 2020In this article, we study differential beamforming from a graph perspective. The microphone array used for differential beamforming is viewed as a graph, where its sensors correspond to the nodes, the number of microphones corresponds to the order of the graph, and linear spatial difference equations among microphones are related to graph edges ...
Gongping Huang +3 more
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On the Robustness of the Superdirective Beamformer
IEEE/ACM Transactions on Audio, Speech, and Language Processing, 2021In microphone array beamforming, a high directional gain is always desired for acoustic noise and reverberation suppression; as a result, the superdirective beamformer has been of great interest in many applications. However, this beamformer is well known to be very sensitive to array imperfections.
Xi Chen 0128 +3 more
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Combined Beamformers for Robust Broadband Regularized Superdirective Beamforming
IEEE/ACM Transactions on Audio, Speech, and Language Processing, 2015Superdirective fixed beamformers are known to attain high directivity factors, but are extremely sensitive to uncorrelated noise and slight errors in the array elements, which are modeled by the beamformer white noise gain measure. The delay-and-sum beamformer, on the other hand, manages to maximize the white noise gain, but suffers from a very low ...
Reuven Berkun +2 more
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Analysis of diversity, beamforming and hybrid diversity-beamforming systems
2003 IEEE International Conference on Acoustics, Speech, and Signal Processing, 2003. Proceedings. (ICASSP '03)., 2004In this paper we compare Shannon capacities of diversity, beamforming, and hybrid diversity-beamforming systems for reverse and forward links. Our results show that the reverse link capacity of a diversity system is higher than that of a beamforming system, while the beamforming system can provide higher capacity than the diversity system in the ...
Mahdi Nezafat, Mostafa Kaveh
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Performance Comparison between Distributed Beamforming and Clustered Beamforming
2014 11th International Conference on Information Technology: New Generations, 2014The performance of transmit beamforming (BF) systems in terms of the spatial correlation coefficient and channel gain variance (CGV) are analyzed over Rayleigh fading channels. We derive bit error rate (BER) of distributed BF (DBF) systems as a function of CGV of distributed channel links.
Sahar Amini, Dong-jun Na, Kwonhue Choi
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International Conference on Acoustics, Speech, and Signal Processing, 2002
It is shown that it is possible to approximate a maximum-likelihood method, leading to a very high performance subspace algorithm. This has all the advantages of subspace methods (i.e. inexpensive), but with much better threshold performance than existing methods such as MUSIC.
David R. Farrier, L. R. Prosper
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It is shown that it is possible to approximate a maximum-likelihood method, leading to a very high performance subspace algorithm. This has all the advantages of subspace methods (i.e. inexpensive), but with much better threshold performance than existing methods such as MUSIC.
David R. Farrier, L. R. Prosper
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Conference Record of the Thirty-Sixth Asilomar Conference on Signals, Systems and Computers, 2002., 2002
The Capon beamformer has better resolution and much better interference rejection capability than the standard (data-independent) beamformer, provided that the array steering vector corresponding to the signal of interest (SOI) is accurately known. However, whenever the knowledge of the SOI steering vector is imprecise (as is often the case in practice)
Petre Stoica, Zhisong Wang, Jian Li 0001
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The Capon beamformer has better resolution and much better interference rejection capability than the standard (data-independent) beamformer, provided that the array steering vector corresponding to the signal of interest (SOI) is accurately known. However, whenever the knowledge of the SOI steering vector is imprecise (as is often the case in practice)
Petre Stoica, Zhisong Wang, Jian Li 0001
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Spherical Fraction Beamforming
IEEE/ACM Transactions on Audio, Speech, and Language Processing, 2020This paper describes a beamforming method for one-eighth, quarter, and half-spaces, bounded by rigid planes. The proposed approach is based on the spherical fraction harmonic decomposition, similar to that of spherical harmonics decomposition for the whole sphere. The definition of these functions is given in detail.
Lecomte, Pierre +2 more
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