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Wyświetlanie 1-15 z 40
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:
Data Reduction Method for Synthetic Transmit Aperture Algorithm
Autorzy:
Karwat, P.
Klimonda, Z.
Sęklewski, M.
Lewandowski, M.
Nowicki, A.
Powiązania:
https://bibliotekanauki.pl/articles/177848.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
ultrasonic imaging
synthetic transmit aperture
data reduction
effective aperture
reciprocity
Opis:
Ultrasonic methods of human body internal structures imaging are being continuously enhanced. New algorithms are created to improve certain output parameters. A synthetic aperture method (SA) is an example which allows to display images at higher frame-rate than in case of conventional beam-forming method. Higher computational complexity is a limitation of SA method and it can prevent from obtaining a desired reconstruction time. This problem can be solved by neglecting a part of data. Obviously it implies a decrease of imaging quality, however a proper data reduction technique would minimize the image degradation. A proposed way of data reduction can be used with synthetic transmit aperture method (STA) and it bases on an assumption that a signal obtained from any pair of transducers is the same, no matter which transducer transmits and which receives. According to this postulate, nearly a half of the data can be ignored without image quality decrease. The presented results of simulations and measurements with use of wire and tissue phantom prove that the proposed data reduction technique reduces the amount of data to be processed by half, while maintaining resolution and allowing only a small decrease of SNR and contrast of resulting images.
Źródło:
Archives of Acoustics; 2010, 35, 4; 635-642
0137-5075
Pojawia się w:
Archives of Acoustics
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:
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:
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:
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 and Optical Images Fusion Using Stripmap SAR Data with Multilook Processing
Autorzy:
Kulpa, K.
Malanowski, M.
Misiurewicz, J.
Samczynski, P.
Powiązania:
https://bibliotekanauki.pl/articles/226571.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Synthetic Aperture Radar (SAR)
focused SAR
multilook
multilook colour mapping
data fusion
Opis:
The paper presents the real-life data results of SAR and optical images data fusion. The fusion has been carried out for SAR images obtained in stripmap SAR mode using multilook processing with different methods of final image creation. The aim of the fusion was to enhance the target recognition capabilities on the Earth surface for a simple single-channel SAR receiver.
Źródło:
International Journal of Electronics and Telecommunications; 2011, 57, 1; 37-42
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:
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:
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:
Comparison of range stacking and omega-k algorithms in synthetic aperture sonar processing
Porównanie algorytmów omega-k oraz range stacking w przetwarzaniu SAS
Autorzy:
Szczegielniak, M.
Szczegielniak, D.
Powiązania:
https://bibliotekanauki.pl/articles/389862.pdf
Data publikacji:
2012
Wydawca:
Politechnika Bydgoska im. Jana i Jędrzeja Śniadeckich. Wydawnictwo PB
Tematy:
synthetic aperture sonar
range stacking
omega-k
comparison
sonar z syntetyczną aperturą
porównanie
Opis:
Synthetic Aperture Sonar (SAS) processing is continuously developing into a direction of better, more effective and accurate algorithms. It is preferable to use algorithms which don’t introduce additional errors because of a phase approximation or digital data interpolation. One of them is Range Stacking. The short analysis of this algorithm, emphasizing its advantages and disadvantages in comparison with another reconstruction algorithm called Omega-k, was carried out in the paper. The simulated raw SAS signals for the stripmap mode were the basis of the practical part of the comparison. The set of examined SAS images included some signals after the spatial filtering with the use of Polar Format Processing. The results of the numerical simulation are shown and discussed in this paper.
Przetwarzanie SAS (Synthetic Aperture Sonar) jest wciąż rozwijane w kierunku lepszych, bardziej efektywnych oraz dokładnych algorytmów. Pożądane jest stosowanie algorytmów, które nie wprowadzają dodatkowych błędów z powodu aproksymacji fazy lub cyfrowej interpolacji danych. Jednym z takich algorytmów jest "Range Stacking". W artykule zaprezentowano jego krótką charakterystykę z wyróżnieniem jego wad i zalet w stosunku do innego, chętnie stosowanego algorytmu rekonstrukcji Omega-k. Wygenerowane sygnały SAS dla trybu "stripmap" zostały wykorzystane do praktycznego porównania obydwu algorytmów. Zbiór symulowanych obrazów SAS zawierał również sygnały przefiltrowane przestrzennie za pomocą algorytmu "Polar Format Processing". Wyniki numerycznych symulacji zostały zaprezentowane i przedyskutowane w artykule.
Źródło:
Zeszyty Naukowe. Telekomunikacja i Elektronika / Uniwersytet Technologiczno-Przyrodniczy w Bydgoszczy; 2012, 16; 27-39
1899-0088
Pojawia się w:
Zeszyty Naukowe. Telekomunikacja i Elektronika / Uniwersytet Technologiczno-Przyrodniczy w Bydgoszczy
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:
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:
Upwelling dynamics in the Baltic Sea studied by a combined SAR-infrared satellite data and circulation model analysis
Autorzy:
Gurova, E.
Lehmann, A.
Ivanov, A.
Powiązania:
https://bibliotekanauki.pl/articles/48338.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Instytut Oceanologii PAN
Tematy:
Baltic Sea
coastal upwelling
MODIS satellite image
circulation model
synthetic aperture radar
sea surface temperature
wind stress
Źródło:
Oceanologia; 2013, 55, 3
0078-3234
Pojawia się w:
Oceanologia
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
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