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Wyświetlanie 1-15 z 31
Tytuł:
Implementation of Adaptive Generalized Sidelobe Cancellers Using Efficient Complex Valued Arithmetic
Autorzy:
Glentis, G. O.
Powiązania:
https://bibliotekanauki.pl/articles/908084.pdf
Data publikacji:
2003
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
elektronika
adaptive beamforming
generalized sidelobe canceller
LMS algorithm
complex valued arithmetic
Opis:
Low complexity realizations of Least Mean Squared (LMS) error, Generalized Sidelobe Cancellers (GSCs) applied to adaptive beamforming are considered. The GSC method provides a simple way for implementing adaptive Linear Constraint Minimum Variance (LCMV) beamformers. Low complexity realizations of adaptive GSCs are of great importance for the design of high sampling rate, and/or small size and low power adaptive beamforming systems. The LMS algorithm and its Transform Domain (TD-LMS) counterpart are considered for the adaptive processing task involved in the design of optimum GSC systems. Since all input signals are represented by complex variables, complex valued arithmetic is utilized for the realization of GSC algorithms, either on general purpose computers, or on dedicated VLSI ASICs. Using algorithmic strength reduction (SR) techniques, two novel algorithms are developed for efficient realizations of both LMS GSCs and TD-LMS GSC schemes. Both of the proposed algorithms are implemented using real valued arithmetic only, whilst reducing the number of multipliers by 25% and 20%, respectively. When VLSI implementation aspects are considered, both the proposed algorithms result in reduced power dissipation and silicon area realizations. The performance of the proposed realizations of the LMS based GSC methods is illustrated in the context of typical beamforming applications.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2003, 13, 4; 549-566
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Wideband beamformer in the frequency domain
Autorzy:
Elminowicz, A.
Powiązania:
https://bibliotekanauki.pl/articles/332683.pdf
Data publikacji:
2003
Wydawca:
Polskie Towarzystwo Akustyczne
Tematy:
acoustics
wideband sonar
beamforming
Opis:
In modern high resolution wideband sonars using linear array, beamforming constitutes one of the most difficult problems. This paper presents a new efficient method of beamforming in the frequency domain. Applying fast Fourier transforms: to transfer into the frequency domain - temporal FFT (TFFT); to make spatial filtration spatial FFT (SFFT) and to transfer from the frequency domain - inverse FFT (IFFT), as well as fast convolution in the frequency domain correlating the conjugated and corrected replicas for each beam with picked up samples of SFFT for each frequency and each beam we obtain a processing that is less calculations burdened than other known processing algorithms.
Źródło:
Hydroacoustics; 2003, 6; 235-242
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A wideband smart antenna employing spatial signal processing
Autorzy:
Uthansakul, M.
Białkowski, M. E.
Powiązania:
https://bibliotekanauki.pl/articles/307580.pdf
Data publikacji:
2007
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
direction estimation
null steering
wideband beamforming
wideband smart antenna
wideband antenna
Opis:
A smart antenna with capability of beam steering in azimuth over a wide frequency band using only spatial signal processing is presented. Filters and tapped-delay networks employed in conventional wideband linear arrays are avoided by using a two-dimensional rectangular array structure. In this array, only constant real-valued weighting coefficients, realized with amplifiers or attenuators, are used to form a desired radiation pattern. In order to estimate direction of arrival of a wideband signal, the MUSIC algorithm in conjunction with an interpolated array technique is applied. In the interpolated array technique, a composite covariance matrix is generated, which is a simple addition of covariance matrices of narrowband virtual arrays, being stretched or compressed versions of a nominal array. A working prototype of this wideband array is presented. Its operation is assessed via full EM simulations and measurements.
Źródło:
Journal of Telecommunications and Information Technology; 2007, 1; 13-17
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Multi-Element Synthetic Transmit Aperture in Medical Ultrasound Imaging
Autorzy:
Trots, I.
Nowicki, A.
Lewandowski, M.
Tasinkevych, Y.
Powiązania:
https://bibliotekanauki.pl/articles/177855.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
ultrasound imaging
synthetic aperture
beamforming
Opis:
Synthetic aperture (SA) technique is a novel approach to present day commercial systems and has previously not been used in medical ultrasound imaging. The basic idea of SA is to combine information acquired simultaneously from all directions over a number of emissions and to reconstruct the full image from these data. The paper presents the multi-element STA (MSTA) method for medical ultrasound imaging. The main difference with the STA approach is the use of a few elements in the transmit mode in contrast to a single element aperture. This allows increasing the system frame rate, decreasing the number of emissions, and provides the best compromise between the penetration depth and lateral resolution. Besides, a modified MSTA is proposed with a corresponding RF signal correction in the receive mode, which accounts for the element directivity property. In the experiments a 32-element linear transducer array with 0.48 mm interelement spacing and a burst pulse of 100 ns duration were used. Two elements wide transmission aperture was used to generate an ultrasound wave covering the full image region. The comparison of 2D ultrasound images of a tissue mimicking phantom obtained using the STA and MSTA methods is presented to demonstrate the benefits of the second one.
Źródło:
Archives of Acoustics; 2010, 35, 4; 687-699
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Wave Generation by a Finite Baffle Array in Application to Beam-Forming Analysis
Autorzy:
Tasinkevych, Y.
Powiązania:
https://bibliotekanauki.pl/articles/177857.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
phased array
beamforming
mixed boundary value problem
BIS expansion
Opis:
Directional excitation of sound in an aperiodic finite baffle system is analyzed using a method developed earlier in electrostatics. The solution to the corresponding boundary value problem is obtained in the spatial-frequency domain. The acoustic pressure and normal particle velocity distribution in acoustic media can be easily computed by the inverse Fourier transform from their spatial spectra on the baffle plane. The presented method can be used for linear acoustic phased arrays modeling with finite element size and inter-element interactions taken into account. Some illustrative numerical examples presenting the far-field radiation pattern and wavebeam steering are given.
Źródło:
Archives of Acoustics; 2010, 35, 4; 677-686
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Golay Coded Sequences in Synthetic Aperture Imaging Systems
Autorzy:
Trots, I.
Tasinkevych, Y.
Nowicki, A.
Lewandowski, M.
Powiązania:
https://bibliotekanauki.pl/articles/176941.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
ultrasound imaging
synthetic aperture
beamforming
radiation pattern
coded sequences
Golay codes
Opis:
The paper presents the theoretical and experimental study of synthetic transmit aperture (STA) method combined with Golay coded transmission for medical ultrasound imaging applications. The transmission of long waveforms characterized by a particular autocorrelation function allows to increase the total energy of the transmitted signal without increasing the peak pressure. It can also improve signal- to-noise ratio and increase the visualization depth maintaining the ultrasound image resolution. In the work the 128-element linear transducer array with 0.3 mm pitch excited by the 8 and 16-bits Golay coded sequences as well as a one cycle at nominal frequencies 4 MHz were used. The comparison of 2D ultrasound images of the tissue mimicking phantoms is presented to demonstrate the benefits of coded transmission. The image reconstruction was performed using synthetic STA algorithm with transmit and receive signals correction based on a single element directivity function.
Źródło:
Archives of Acoustics; 2011, 36, 4; 913-926
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Review of Distributed Beamforming
Autorzy:
Her, J.
Wysoki, T. A.
Wysoki, B. J.
Powiązania:
https://bibliotekanauki.pl/articles/309541.pdf
Data publikacji:
2011
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
beamforming
distributed antenna array
smart antenna
virtual array
Opis:
As the capabilities of individual nodes in wireless sensor networks increase, so does the opportunity to perform more complicated tasks, such as cooperative distributed beamforming to improve the range of communications and save precious battery power during the transmission.This work presents a review of the current literature focused on implementing distributed beamformers; covering the calculation of ideal beamforming weights, practical considerations such as carrier alignment, smart antennas based on distributed beamformers, and open research problems in the field of distributed beamforming.
Źródło:
Journal of Telecommunications and Information Technology; 2011, 1; 78-88
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Sound recording with the application of microphone arrays
Autorzy:
Kornatowski, E.
Powiązania:
https://bibliotekanauki.pl/articles/97513.pdf
Data publikacji:
2011
Wydawca:
Politechnika Poznańska. Wydawnictwo Politechniki Poznańskiej
Tematy:
sound recording
array microphone
beamforming
microphone
Opis:
In this article the issues concerning sound recording with the use of three-dimensional systems of several microphones were considered. The issues under study concern the so called beamforming, which is modeling three-dimensional directivity patterns of microphone arrays, as well as modern technologies of multichannel recording production with the purpose of reproduction in surround sound systems.
Źródło:
Computer Applications in Electrical Engineering; 2011, 9; 213-222
1508-4248
Pojawia się w:
Computer Applications in Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optimization of the Multi-element Synthetic Transmit Aperture Method for Medical Ultrasound Imaging Applications
Autorzy:
Tasinkevych, Y.
Trots, I.
Nowicki, A.
Lewandowski, M.
Powiązania:
https://bibliotekanauki.pl/articles/177208.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
ultrasound imaging
synthetic aperture
beamforming
Opis:
The paper presents the optimization problem for the multi-element synthetic transmit aperture method (MSTA) in ultrasound imaging applications. The optimal choice of the transmit aperture size is made as a trade-off between the lateral resolution, penetration depth and the frame rate. Results of the analysis obtained by a developed optimization algorithm are presented. The maximum penetration depth and lateral resolution at given depths are chosen as optimization criteria. The results of numerical experiments carried out in MATLAB Ž using synthetic aperture data of point reflectors obtained by the FIELD II simulation program are presented. The visualization of experimental synthetic aperture data of a tissue mimicking phantom and in vitro measurements of the beef liver performed using the SonixTOUCH Research system are also shown.
Źródło:
Archives of Acoustics; 2012, 37, 1; 47-55
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Accurate Phase Calibration for Digital Beam-Forming in Multi-Transceiver HF Radar System
Autorzy:
Nguyen, H. Q.
Whittington, J. S.
Devlin, J. C.
Vu, H. L.
Vu, N. V.
Custovic, E.
Powiązania:
https://bibliotekanauki.pl/articles/227073.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
digital beamforming
phased array antenna
phase calibration
radar
transceivers
Opis:
The TIGER-3 radar is being developed as an “all digital” radar with 20 integrated digital transceivers, each connected to a separate antenna. Using phased array antenna techniques, radiated power is steered towards a desired direction based on the relative phases within the array elements. This paper proposes an accurate phase measurement method to calibrate the phases of the radio output signals using Field Programmable Gate Array (FPGA) technology. The method sequentially measures the phase offset between the RF signal generated by each transceiver and a reference signal operated at the same frequency. Accordingly, the transceiver adjusts its phase in order to align to the reference phase. This results in accurately aligned phases of the RF output signals and with the further addition of appropriate phase offsets, digital beamforming (DBF) can be performed steering the beam in a desired direction. The proposed method is implemented on a Virtex-5 VFX70T device. Experimental results show that the calibration accuracy is of 0.153 degrees with 14 MHz operating frequency.
Źródło:
International Journal of Electronics and Telecommunications; 2013, 59, 3; 245-254
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Antena z elektronicznie sterowaną wiązką na pasmo S
Electronically steered antenna for S-band
Autorzy:
Stec, B.
Czyżewski, M.
Słowik, A.
Powiązania:
https://bibliotekanauki.pl/articles/208950.pdf
Data publikacji:
2013
Wydawca:
Wojskowa Akademia Techniczna im. Jarosława Dąbrowskiego
Tematy:
telekomunikacja
antena planarna
układ formowania
wiązki antenowej
antena sterowana elektronicznie
telecommunication
electronically steered antenna
planar antenna
antenna beamforming network
Opis:
We współczesnych rozwiązaniach urządzeń radioelektronicznych anteny ze sterowaną elektronicznie wiązką antenową, mimo swojej złożoności układowej, są rozwiązaniem coraz częściej wykorzystywanym. Główną ich zaletą jest możliwość bardzo szybkiej zmiany kierunku maksymalnego promieniowania, przy zachowaniu dobrych parametrów kierunkowych. Oprócz samej konstrukcji anteny, w takich rozwiązaniach niezwykle ważny jest układ formowania wiązki. Najczęściej sterowany jest on cyfrowo, poprzez komputer lub dedykowany układ cyfrowy, z poziomu programowego. Często układ ten decyduje o parametrach całej anteny. Przedstawiona antena została zaprojektowana na pasmo S, na potrzeby zastosowania jej w radarze do lokalizacji istot żywych, umieszczonych za zasłonami typu ściana. Jej konstrukcja umożliwia ustawienie kierunku maksymalnego promieniowania dla pięciu położeń kątowych, pokrywając całkowity sektor obserwacji ok. 100° w azymucie. Wiązka w elewacji posiada stałą szerokość listka głównego, wynoszącą ok. 35°. Elektroniczne sterowanie zapewnia bardzo szybki obrót wiązki w kącie azymutalnym, w czasie poniżej 1 µs. Antena pracuje szerokopasmowo, z pasmem pracy około 500 MHz. Struktura elementów promieniujących wraz z układem rozdziału mocy i dopasowania została wykonana w technologii niesymetrycznych linii paskowych na laminacie FR4. Układ formowania wiązki zrealizowany został w oparciu o elektroniczne przełączniki mikrofalowe oraz linie opóźniające, wprowadzające odpowiednie opóźnienia fazowe. Stanowi on integralną część anteny.
The electronically steered antennas are nowadays much often used in modern telecommunication systems, despite much more complicated circuit structure. The most important merit is very rapid mainlobe direction turning, with good directional parameters maintain. This one is steered digitally, using computer or dedicated digital circuit, from programming level. Often, this circuit decides about the parameters of the whole antenna system. The described antenna was designed to work in S-band, for using it in radar for localization of living human through the wall. The mainlobe direction can be set for five angle values, covering angle sector about 100° in the azimuth plane. In elevation plane, the mainlobe width has fixed value of about 35°. Electronically steering lets very quickly mainlobe turning in elevation, in time below 1 µs. The antenna works wideband, with about 500-MHz band. The radiating elements structure with power distribution and matching network in the microstrip line technology on the FR4 substrate was made. Beamforming network, basing on the microwave electronic switches and delay lines, was made. This one is digitally steered and it is an integral part of the whole antenna system.
Źródło:
Biuletyn Wojskowej Akademii Technicznej; 2013, 62, 2; 75-85
1234-5865
Pojawia się w:
Biuletyn Wojskowej Akademii Technicznej
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An Introduction to Virtual Phased Arrays for Beamforming Applications
Autorzy:
Comesaña, D. F.
Holland, K. R.
Escribano, D. G.
de Bree, H. E.
Powiązania:
https://bibliotekanauki.pl/articles/176345.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
beamforming
source localization
virtual phased arrays
measurement techniques
Opis:
Sound localization problems are usually tackled by the acquisition of data from phased microphone arrays and the application of acoustic holography or beamforming algorithms. However, the number of sensors required to achieve reliable results is often prohibitive, particularly if the frequency range of interest is wide. It is shown that the number of sensors required can be reduced dramatically providing the sound field is time stationary. The use of scanning techniques such as “Scan & Paint” allows for the gathering of data across a sound field in a fast and efficient way, using a single sensor and webcam only. It is also possible to characterize the relative phase field by including an additional static microphone during the acquisition process. This paper presents the theoretical and experimental basis of the proposed method to localise sound sources using only one fixed microphone and one moving acoustic sensor. The accuracy and resolution of the method have been proven to be comparable to large microphone arrays, thus constituting the so called “virtual phased arrays”.
Źródło:
Archives of Acoustics; 2014, 39, 1; 81-88
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Circular Radon Transform Inversion Technique in Synthetic Aperture Ultrasound Imaging : an Ultrasound Phantom Evaluation
Autorzy:
Tasinkevych, J.
Trots, I.
Powiązania:
https://bibliotekanauki.pl/articles/176632.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
synthetic aperture focusing method
circular Radon Transform
delay and sum beamforming
range migration algorithm
Opis:
The paper presents an overview of theoretical aspects of ultrasound image reconstruction techniques based on the circular Radon transform inversion. Their potential application in ultrasonography in a similar way as it was successfully done in the x-ray computer tomography is demonstrated. The meth- ods employing Radon transform were previously extensively explored in the synthetic aperture radars, geophysics, and medical imaging using x-ray computer tomography. In this paper the main attention is paid to the ultrasound imaging employing monostatic transmit-receive configuration. Specifically, a single transmit and receive omnidirectional source placed at the same spatial location is used for generation of a wide-band ultrasound pulse and detection of back-scattered waves. The paper presents derivation of the closed-form solution of the CRT inversion algorithms by two different approaches: the range-migration algorithm (RMA) and the deconvolution algorithm (DA). Experimentally determined data of ultrasound phantom obtained using a 32-element 5 MHz linear transducer array with 0.48 mm element pitch and 0.36 mm element width and 5 mm height, excited by a 2 sine cycles burst pulse are used for comparison of images reconstructed by the RMA, DA, and conventional synthetic aperture focusing technique (SAFT). It is demonstrated that both the RMA and SAFT allow better lateral resolution and visualization depth to be achieved as compared to the DA approach. Comparison of the results obtained by the RMA method and the SAFT indicates slight improvement of the lateral resolution for the SAFT of approximately 1.5 and 1.6% at the depth of 12 and 32 mm, respectively. Concurrently, however, the visualization depth increase for the RMA is shown in comparison with the SAFT. Specifically, the scattered echo amplitude increase by the factor of 1.36 and 1.12 at the depth of 22 and 32 mm is demonstrated. It is also shown that the RMA runs about 30% faster than the SAFT and about 12% faster than the DA method.
Źródło:
Archives of Acoustics; 2014, 39, 4; 569-582
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Digital Signal Processing Approach in Air Coupled Ultrasound Time Domain Beamforming
Autorzy:
Herman, K.
Gudra, T.
Furmankiewicz, J.
Powiązania:
https://bibliotekanauki.pl/articles/177033.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
beamforming
air-coupled ultrasounds
DSP
digital signal processing
bat signals
direction of arrival
Opis:
The work presents the results of experimental study on the possibilities of determining the source of an ultrasonic signal in two-dimensional space (distance, horizontal angle). During the research the team used a self-constructed linear array of MEMS microphones. Knowledge in the field of sonar systems was utilized to analyse and design a location system based on a microphone array. Using the above mentioned transducers and broadband ultrasound sources allows a quantitative comparison of estimation of the location of an ultrasonic wave source with the use of broadband modulated signals (modelled on bats’ echolocation signals) to be performed. During the laboratory research the team used various signal processing algorithms, which made it possible to select an optimal processing strategy, where the sending signal is known.
Źródło:
Archives of Acoustics; 2014, 39, 1; 37-50
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Prototype measurement system for localization of partial discharges sources – microphone array
Autorzy:
Polak, F.
Sikorski, W.
Siodła, K.
Powiązania:
https://bibliotekanauki.pl/articles/97228.pdf
Data publikacji:
2015
Wydawca:
Politechnika Poznańska. Wydawnictwo Politechniki Poznańskiej
Tematy:
partial discharges (PDs)
PD localization
sensor array
microphone array
beamforming
direction-of-arrival (DOA)
Opis:
This paper presents a prototype measurement system, that will be used for localization of acoustic emission sources originating from partial discharges (PD). It is based on sensor arrays technology and direction of arrival estimation algorithms. Acoustic signals will be received with a universal linear array (ULA) of sensors, wherein the sensory elements are microphones operating in the audible frequency range. For the estimation of the direction of arrival of these signals conventional beamforming algorithm is used which has also been described theoretically. Ultimately, the system will be used to determine the direction of arrival of the acoustic signal generated by the insulation defect, which is corona discharge.
Źródło:
Computer Applications in Electrical Engineering; 2015, 13; 209-219
1508-4248
Pojawia się w:
Computer Applications in Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 31

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