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Tytuł:
Ultrasonic Synthetic Apertures: Review
Autorzy:
Nowicki, A.
Gambin, B.
Powiązania:
https://bibliotekanauki.pl/articles/176456.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
synthetic aperture
effective aperture
ultrasonography
Opis:
In the paper the concept of synthetic aperture used for high resolution/high frame rate ultrasonic imaging is reviewed. The synthetic aperture technique allows building extended “virtual” apertures, synthesized from smaller real aperture resulting in improved lateral resolution along full penetration depth without sacrificing the frame rate. Especially, four methods, synthetic aperture focusing (SAF), multi-element synthetic aperture focusing (M-SAF), synthetic receive aperture (SRA) and synthetic transmit aperture (STA) are addressed. The effective aperture function, describing two-way, far field radiation is a useful tool in beam pattern analysis. Some basic notations, which are used to calculate the effective aperture are introduced in Appendix.
Źródło:
Archives of Acoustics; 2014, 39, 4; 427-438
0137-5075
Pojawia się w:
Archives of Acoustics
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:
A Short Range Synthetic Aperture Imaging Radar with Rotating Antenna
Autorzy:
Ali, F.
Urban, A.
Vossiek, M.
Powiązania:
https://bibliotekanauki.pl/articles/226520.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
radar
synthetic aperture
scanning
imaging
Opis:
The design of a short range synthetic aperture imaging radar is introduced in this paper. A radar hologram is acquired using a small omnidirectional antenna that is mounted on a rotating platform. After each turn of the platform a high resolution 360° 2D image is reconstructed; a rotating window function optimizes the reconstructed image function to get the best image focus for detecting both weak and strong scatterers. The rotating window function depends on the target direction and is executed for each image point and each target direction. The size of the synthetic aperture – and thus the lateral resolution of the imaging system – is determined by the diameter of the circular antenna trajectory. In contrast to common radar scanner concepts that utilize highly directional and thus bulky antennas, the proposed scanner concept has the advantage of using a small, lightweight omni-directional antenna. The developed radar system is much more compact and the scanning mechanics are significantly simplified. Furthermore, an omni-directional antenna offers very straightforward options for powering the radar on the rotation platform. Measurement results obtained with a 24 GHz FMCW short range radar sensor illustrate the performance of the proposed SAR imaging method.
Źródło:
International Journal of Electronics and Telecommunications; 2011, 57, 1; 97-102
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
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:
Synthetic Aperture Radar Using Emitters of Opportunity
Autorzy:
Serafin, P.
Kawalec, A.
Leśnik, C.
Pyć, M.
Pietrasiński, J.
Powiązania:
https://bibliotekanauki.pl/articles/226408.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Synthetic Aperture Radar (SAR)
passive SAR
Opis:
The capability of a radar imaging system to stay undetected while gathering data is one of the most desired for military reconnaissance systems. This is particularly difficult to achieve for synthetic aperture radar (SAR), that have to emit electromagnetic energy all the time during the operation and to move along a strictly defined route. Therefore the idea of a passive imaging system although encountering many constraints seems to be very interesting. The possibilities of a passive synthetic aperture radar system working with different types of emitters of opportunity are described in the paper. Impact of signal characteristics on image quality and geometry issues are discussed among others. Results of computer simulations of such a system implementing different imaging algorithms as well as the results of the experiment performed with passive SAR system model are presented.
Źródło:
International Journal of Electronics and Telecommunications; 2012, 58, 4; 357-362
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Object georeferencing in UAV-based SAR terrain images
Autorzy:
Łabowski, M.
Kaniewski, P.
Serafin, P.
Wajszczyk, B.
Powiązania:
https://bibliotekanauki.pl/articles/320583.pdf
Data publikacji:
2016
Wydawca:
Polskie Forum Nawigacyjne
Tematy:
georeferencing
synthetic aperture radar
IMU
GNSS
Opis:
Synthetic aperture radars (SAR) allow to obtain high resolution terrain images comparable with the resolution of optical methods. Radar imaging is independent on the weather conditions and the daylight. The process of analysis of the SAR images consists primarily of identifying of interesting objects. The ability to determine their geographical coordi-nates can increase usability of the solution from a user point of view. The paper presents a georeferencing method of the radar terrain images. The presented images were obtained from the SAR system installed on board an Unmanned Aerial Vehicle (UAV). The sys-tem was developed within a project under acronym WATSAR realized by the Military University of Technology and WB Electronics S.A. The source of the navigation data was an INS/GNSS system integrated by the Kalman filter with a feed-backward correc-tion loop. The paper presents the terrain images obtained during flight tests and results of selected objects georeferencing with an assessment of the accuracy of the method.
Lotnicze zobrazowania terenu realizowane za pomocą radaru z syntetyczną aperturą pozwalają na uzyskanie wysokiej rozróżnialności porównywalnej z rozróżnialnością metod optycznych, mając jednocześnie nad nimi przewagę w postaci niezależności obserwacji od warunków pogodowych czy pory dnia. Proces analizy tak uzyskanych zobrazowań składa się przede wszystkim z identyfikacji interesujących obiektów. Możliwość określenia ich współrzędnych geograficznych pozwala na znaczące zwiększenie użyteczności tego rozwiązania z punktu widzenia potencjalnego użytkownika. W artykule przedstawiono metodę georeferencji zobrazowań terenu otrzymywanych za pomocą radaru z syntetyczną aperturą, który zainstalowano na pokładzie bezzałogowego statku powietrznego. System taki opracowano w ramach projektu WATSAR, zrealizowanego przez Wojskową Akademię Techniczną i WB Electronics S.A. Źródłem danych nawigacyjnych był system INS/GNSS, zintegrowany metodą filtracji pośredniej, z korekcją wstecz. W artykule zamieszczono radarowe zobrazowania terenu uzyskane podczas badań poligonowych systemu oraz wyniki georeferencji wybranych obiektów wraz z oceną dokładności wyznaczanego położenia.
Źródło:
Annual of Navigation; 2016, 23; 39-52
1640-8632
Pojawia się w:
Annual of Navigation
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application for Displaying Synthetic Aperture Radar Imagery in Real-time Implementation and Results
Autorzy:
Borowiec, K.
Powiązania:
https://bibliotekanauki.pl/articles/226659.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Synthetic Aperture Radar (SAR)
real-time imaging
Opis:
The paper presents implementation and results of the application for displaying SAR (Synthetic Aperture Radar) imagery operating in real-time. The application performs SAR imagery formation and displays results in real-time after receiving of preprocessed data via an SAR processing application. The application was used in SARape (Synthetic Aperture Radar for all weather penetrating UAV application) project founded by the European Defence Agency. The real-time operation is achieved thanks to implementation based on multithreading.
Źródło:
International Journal of Electronics and Telecommunications; 2015, 61, 4; 345-350
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Synthetic Aperture Technique Applied to Tissue Attenuation Imaging
Autorzy:
Klimonda, Z.
Litniewski, J.
Nowicki, A.
Powiązania:
https://bibliotekanauki.pl/articles/176945.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
tissue attenuation imaging
synthetic aperture
diagnosis enhancing
Opis:
The attenuating properties of biological tissue are of great importance in ultrasonic medical imaging. Investigations performed in vitro and in vivo showed the cor- relation between pathological changes in the tissue and variation of the attenuation coefficient. In order to estimate the attenuation we have used the downshift of mean frequency (fm) of the interrogating ultrasonic pulse propagating in the medium. To determine the fm along the propagation path we have applied the fm estimator (I/Q algorithm adopted from the Doppler mean frequency estimation technique). The mean-frequency shift trend was calculated using Single Spectrum Analysis. Next, the trends were converted into attenuation coefficient distributions and finally the parametric images were computed. The RF data were collected in simulations and experiments applying the synthetic aperture (SA) transmit-receiving scheme. In measurements the ultrasonic scanner enabling a full control of the transmission and reception was used. The resolution and accuracy of the method was verified using tissue mimicking phantom with uniform echogenicity but varying attenuation coefficient.
Źródło:
Archives of Acoustics; 2011, 36, 4; 927-935
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Cascade Feed Forward Neural Network-based Model for Air Pollutants Evaluation of Single Monitoring Stations in Urban Areas
Autorzy:
Capizzi, G.
Lo Sciuto, G.
Monforte, P.
Napoli, C.
Powiązania:
https://bibliotekanauki.pl/articles/226736.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
neural networks
Synthetic Aperture Radar (SAR)
mahalanobis distance
Opis:
In this paper, air pollutants concentrations for NO2, NO, NOx and PM10 in a single monitoring station are predicted using the data coming from other different monitoring stations located nearby. A cascade feed forward neural network based modeling is proposed. The main aim is to provide a methodology leading to the introduction of virtual monitoring station points consistent with the actual stations located in the city of Catania in Italy.
Źródło:
International Journal of Electronics and Telecommunications; 2015, 61, 4; 327-332
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Generalized radar/radiometry imaging problems
Autorzy:
Prudyus, I.
Voloshynovskiy, S.
Synyavskyy, A.
Holotyak, T.
Lazko, L.
Powiązania:
https://bibliotekanauki.pl/articles/309072.pdf
Data publikacji:
2001
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
radiometry systems
Synthetic Aperture Radar (SAR)
spatio-temporal imaging
Opis:
In the paper the results of spatio-temporal imaging simulation based on radar, synthetic aperture radar (SAR) and radiometry systems are presented. The analytical relationship between object scattering/emitting and the formed image is given and the general approach for the description of imaging system by means of Frendholm equation solution is developed. The potential limit of image resolution based on Rao-Cramer inequality is estimated.
Źródło:
Journal of Telecommunications and Information Technology; 2001, 4; 15-20
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mutually Orthogonal Golay Complementary Sequences in Synthetic Aperture Imaging Systems
Autorzy:
Trots, I.
Powiązania:
https://bibliotekanauki.pl/articles/178145.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
coded excitation
mutually orthogonal Golay codes
synthetic aperture
ultrasound imaging
Opis:
The main objective of this study is to improve the ultrasound image by employing a new algorithm based on transducer array element beam pattern correction implemented in the synthetic transmit aperture (STA) method combined with emission of mutually orthogonal complementary Golay sequences. Orthogonal Golay sequences can be transmitted and received by different transducer elements simultaneously, thereby decreasing the time of image reconstruction, which plays an important role in medical diagnostic imaging. The paper presents the preliminary results of computer simulation of the synthetic aperture method combined with the orthogonal Golay sequences in a linear transducer array. 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 the signal-to-noise ratio and increase the visualization depth maintaining the ultrasound image resolution. In the work, the 128-element linear transducer array with a 0.3 mm pitch excited by 8-bits Golay coded sequences as well as one cycle at nominal frequencies of 4 MHz were used. The comparison of 2D ultrasound images of the phantoms is presented to demonstrate the benefits of a coded transmission. The image reconstruction was performed using the synthetic STA algorithm with transmit and receive signals correction based on a single element directivity function.
Źródło:
Archives of Acoustics; 2015, 40, 2; 283-289
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spatially Diverse ISAR Imaging for Classification Performance Enhancement
Autorzy:
Brisken, S.
Matthes, D.
Mathy, T.
Worms, J. G.
Powiązania:
https://bibliotekanauki.pl/articles/226557.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
inverse synthetic aperture radar
multistatic radar
non-cooperative target identification
Opis:
One popular approach to the problem of Non-Cooperative Target Identification is the use of 2D Inverse SAR images. Methods to successfully identify a target include the comparison of a set of scattering centers in the ISAR image to a database or the estimation of target dimensions. While working well in theory, these techniques face major difficulties in practice. In the conventional case of a monostatic radar, visibility of scattering centers varies with the target aspect angle due to fading. In this paper we examine that the visibility of scattering centers can be improved by incoherent addition of images from spatially distributed radars. The main focus lies in the description and results of a multistatic ISAR experiment carried out at Fraunhofer FHR. We display theoretically derived bistatic synchronization errors in a practical system and formulate additional multistatic synchronization requirements, necessary to add up the images.
Źródło:
International Journal of Electronics and Telecommunications; 2011, 57, 1; 15-22
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nonuniform Spatial Sampling in a Ground-Based Noise SAR
Autorzy:
Maślikowski, Ł.
Misiurewicz, J.
Powiązania:
https://bibliotekanauki.pl/articles/226510.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
nonuniform sampling
noise radar
synthetic aperture
radar (SAR)
compressive sampling
Opis:
The paper presents an idea of nonuniform spatial sampling applied to a noise synthetic aperture radar. In certain cases it is desirable to limit the number of spatial (alongtrack) domain samples acquired in a SAR radar because of external constraints on sampling frequency or on the overall number of samples – e.g. in order to economy on time or power consumed. Lowering number of samples taken may, however, lead to spatial aliasing and incorrect reconstruction of the image. Nonuniform sampling allows to reduce the aliasing effect and reconstruct the image better. This technique can be applied with standard reconstruction methods, but it works best together with Compressive Sensing reconstruction algorithms. The idea will be verified with an experimental noise SAR built at ISE PW.
Źródło:
International Journal of Electronics and Telecommunications; 2011, 57, 1; 71-75
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Radar Signatures of Complex Buried Objects in Ground Penetrating Radar
Autorzy:
Panzner, B.
Jöstingmeier, A.
Omar, A.
Powiązania:
https://bibliotekanauki.pl/articles/226559.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
image reconstruction
inverse scattering
Synthetic Aperture Radar (SAR)
GPR
migration
Opis:
The evaluation of radar signatures of buried objects for three experimental ground penetrating radar setups will be addressed in this paper. The contribution will present corresponding results and experiences. The performance of the imaging capabilities of the designed radar system will be assessed by reconstruction of complex shaped test objects, which have been placed within the ground. The influence of system parameters of the ground penetrating radar have been varied systematically in order to analyze their effects on the image quality. Among the modified parameters are the step size in transverse plane, height of the antenna over ground, frequency range, frequency points, antennas and varying instrument settings. A signal processing technique based on synthetic aperture radar has been applied on the measured raw data. The focus radius around a specific target has been analyzed concerning the compromise between image quality and processing time. The experiments demonstrate that the designed ground penetrating radar systems are capable for detection of buried objects with high resolution.
Źródło:
International Journal of Electronics and Telecommunications; 2011, 57, 1; 9-14
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optimization of Short-Lag Spatial Coherence Imaging Method
Autorzy:
Domaradzki, Jakub
Lewandowski, Marcin
Żołek, Norbert
Powiązania:
https://bibliotekanauki.pl/articles/176815.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
short lag spatial coherence
synthetic aperture
algorithm optimization
parallel processing
Opis:
The computing performance optimization of the Short-Lag Spatial Coherence (SLSC) method applied to ultrasound data processing is presented. The method is based on the theory that signals from adjacent receivers are correlated, drawing on a simplified conclusion of the van Cittert-Zernike theorem. It has been proven that it can be successfully used in ultrasound data reconstruction with despeckling. Former works have shown that the SLSC method in its original form has two main drawbacks: time-consuming processing and low contrast in the area near the transceivers. In this study, we introduce a method that allows to overcome both of these drawbacks. The presented approach removes the dependency on distance (the “lag” parameter value) between signals used to calculate correlations. The approach has been tested by comparing results obtained with the original SLSC algorithm on data acquired from tissue phantoms. The modified method proposed here leads to constant complexity, thus execution time is independent of the lag parameter value, instead of the linear complexity. The presented approach increases computation speed over 10 times in comparison to the base SLSC algorithm for a typical lag parameter value. The approach also improves the output image quality in shallow areas and does not decrease quality in deeper areas.
Źródło:
Archives of Acoustics; 2019, 44, 4; 669-679
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 40

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