Browsing by Subject "Phased arrays"

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    Extension of forward-backward method with DFT-based acceleration algorithm for the efficient analysis of large periodic arrays with arbitrary boundaries
    (John Wiley & Sons, 2005) Civi, Ö. A.; Ertürk, V. B.; Chou, H.-T.
    An extension of the discrete Fourier transform (DFT)-based forward-backward algorithm is developed using the virtual-element approach to provide a fast and accurate analysis of electromagnetic radiation/scattering from electrically large, planar, periodic, finite (phased) arrays with arbitrary boundaries. Both the computational complexity and storage requirements of this approach are O(Ntot) (Ntot is the total number of unknowns). The numerical results for both printed and freestanding dipole arrays with circular and/or elliptical boundaries are presented to validate the efficiency and accuracy of this approach.
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    VLSI circuits for adaptive digital beamforming in ultrasound imaging
    (IEEE, 1993) Karaman, M.; Atalar, Abdullah; Köymen, Hayrettin
    For phased-array ultrasound imaging, alternative beamforming techniques and their VLSI circuits are studied to form a fully digital receive front-end hardware. In order to increase the timing accuracy in beamforming, a computationally efficient interpolation scheme to increase the sampling rate is examined. For adaptive beamforming, a phase aberration correction method with very low computational complexity is described. Image quality performance of the method is examined by processing the non-aberrated and aberrated phased-array experimental data sets of an ultrasound resolution phantom. A digital beamforming scheme based on receive focusing at the raster focal points is examined. The sector images of the resolution phantom, reconstructed from the phased-array experimental data by beamforming at the radial and raster focal points, are presented for comparison of the image resolution performances of the two beamforming schemes. VLSI circuits and their implementations for the proposed techniques are presented.
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    A VLSI receive beamformer for digital ultrasound imaging
    (IEEE, 1992-03) Karaman, Mustafa; Kolağasıoğlu, Ertuğrul; Atalar, Abdullah
    A VLSI architecture for real-time digital receive beamforming in phased array ultrasound imaging is proposed. The architecture is an inverse binary tree like structure with N stages where N is the number of array elements. The sampled signals from the phased array channels are coherently added in a pairwise manner within the stages of the architecture in a pipelined data flow scheme. The storage requirement for the synchronization of the asynchronously received samples corresponding to a focal point is significantly reduced. The architecture is modular and has a regular communication scheme which make the VLSI implementation rather easy and straightforward.