Synthetic-aperture radar processing using fast factorized back-projection

Ulander, Lars M. H.; Hellsten, Hans; Stenström, G.

doi:10.1109/taes.2003.1238734

Cited by 658 publications

(458 citation statements)

References 23 publications

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“…Let and be the discrete sets of -crossrange and -downrange positions, respectively. Consider an arbitrary position , the backprojected beamformed image pixel value at location , denoted with , is given by [18]- [20], (3) where is the convolution operator. In practice, the time-delays in (3) can be implemented off-line using the FFT via the Fourier (time) shift theorem.…”

Section: Free Space Imaging Preliminariesmentioning

confidence: 99%

Multipath Exploitation in Non-LOS Urban Synthetic Aperture Radar

Setlur

Negishi

Devroye

et al. 2014

IEEE J. Sel. Top. Signal Process.

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Abstract-Multipath is exploited to image targets that are hidden due to lack of line of sight (LOS) path in urban environments. Urban radar scenes include building walls, therefore creating reflections causing multipath returns. Conventional processing via synthetic aperture beamforming algorithms do not detect or localize the target at its true position. To remove these limitations, two multipath exploitation techniques to image a hidden target at its true location are presented under the assumptions that the locations of the reflecting walls are known and that the target multipath is resolvable and detectable. The first technique directly operates on the radar returns, whereas the second operates on the traditional beamformed image. Both these techniques mitigate the false alarms arising from the multipath while simultaneously permitting the shadowed target to be detected at its true location. While these techniques are general, they are examined for two important urban radar applications: detecting shadowed targets in an urban canyon, and detecting shadowed targets around corners.

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Section: Free Space Imaging Preliminariesmentioning

confidence: 99%

Multipath Exploitation in Non-LOS Urban Synthetic Aperture Radar

Setlur

Negishi

Devroye

et al. 2014

IEEE J. Sel. Top. Signal Process.

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“…In multistage backprojection techniques such as [29,30] there are many stages involved in moving target SAR processing.…”

Section: Discussionmentioning

confidence: 99%

Optimum relative speed discretisation for detection of moving objects in wide band SAR

Pettersson

2007

IET Radar Sonar Navig.

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This is an author produced version of a paper published in IET Radar, Sonar and Navigation. This paper has been peer-reviewed but may not include the final publisher proof-corrections or journal pagination.Citation for the published paper: Mats I. Pettersson Optimum relative speed discretisation for detection of moving objects in wide band SAR IET Radar, Sonar and Navigation Volume 1, Issue 3, page 213-220, Year 2007 Access to the published version may require subscription. Published with permission from: IET Abstract: This paper considers Ground Moving Target Indication (GMTI) using Synthetic Aperture Radar (SAR). SAR GMTI requires that Relative Speed between the target and the SAR platform is included in the detection algorithm. A separation between the true Relative Speed and the Relative Speed used in the SAR process will cause unfocused targets, and decrease detectability. Blind hypotheses of Relative Speeds are used in the detection phase of moving targets in SAR.The step size between the hypotheses (or, discretization step) in Relative Speed involves a trade off between the number of hypotheses to test and detectability. A large number of tests will increase detectability but will also increase computation load and vice versa. The relevance of Relative Speed increases as the azimuth integration time gets larger. Long integration time is associated with low signature moving target detection in strong clutter environments, or for SAR GMTI at low frequencies. In this paper we determine the optimum discretization of Normalized Relative Speed (NRS) for moving target detection. The optimum discretization is derived from the moving target impulse response. Use of optimum discretization reduces the computation burden in SAR GMTI and secures the detectability.

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“…A computationally efficient method for creating the image is the Fast Factorized Back-Projection (FFBP) [13]. In FFBP, the whole image initially consists of a large number of small subimages with low angular resolution.…”

Section: A Image Formingmentioning

confidence: 99%

Programming Real-Time Autofocus on a Massively Parallel Reconfigurable Architecture Using Occam-pi

Zain-ul-Abdin

Åhlander²,

Svensson

2011

2011 IEEE 19th Annual International Symposium on Field-Programmable Custom Computing Machines

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Abstract-Recently we proposed occam-pi as a high-level language for programming massively parallel reconfigurable architectures. The design of occam-pi incorporates ideas from CSP and pi-calculus to facilitate expressing parallelism and reconfigurability. The feasability of this approach was illustrated by building three occam-pi implementations of DCT executing on an Ambric. However, because DCT is a simple and wellstudied algorithm it remained uncertain whether occam-pi would also be effective for programming novel, more complex algorithms.In this paper, we demonstrate the applicability of occam-pi for expressing various degrees of parallelism by implementing a significantly large case-study of focus criterion calculation in an autofocus algorithm on the Ambric architecture. Autofocus is a key component of synthetic aperture radar systems. Two implementations of focus criterion calculation were developed and evaluated on the basis of performance. The comparison of the performance results with a single threaded software implementation of the same algorithm show that the throughput of the two implementations are 11x and 23x higher than the sequential implementation despite a much lower (9x) clock frequency. The two designs are, respectively, 29x and 40x more energy efficient. I. INTRODUCTION AND MOTIVATIONEmbedded signal processing systems are facing the challenges of increased computational demands. Massively parallel reconfigurable architectures, which can be configured to form application-specific hardware, offer high degree of parallelism to meet the application requirements. However, the applicability of reconfigurable processor arrays in embedded and high performance computing is constrained by the need for mastering low-level structural description languages and the lack of support in these languages for expressing dynamic reconfiguration. Clearly, all these challenges need to be taken care of by using an appropriate programming model.We proposed to use a concurrent programming model that allows the programmer to express computations in a productive manner by matching it to the target hardware using highlevel constructs, and the language is further supported by a compiler for providing portability across different hardware resources. Occam [2] is a programming language based on the Communicating Sequential Processes (CSP) [1] concurrent model of computation and was developed by Inmos for their microprocessor chip Transputer. However, CSP can only express a static model of the application, where processes synchronize through communication over fixed channels. In contrast, the pi-calculus [3] allows modeling of dynamic construc-

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Synthetic-aperture radar processing using fast factorized back-projection

Cited by 658 publications

References 23 publications

Multipath Exploitation in Non-LOS Urban Synthetic Aperture Radar

Multipath Exploitation in Non-LOS Urban Synthetic Aperture Radar

Optimum relative speed discretisation for detection of moving objects in wide band SAR

Programming Real-Time Autofocus on a Massively Parallel Reconfigurable Architecture Using Occam-pi

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