Imaging the rotor blades of hovering helicopters with SAR

Barber, B.C.

doi:10.1109/radar.2008.4720849

Cited by 13 publications

(6 citation statements)

References 3 publications

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“…For example, Ruegg studied two typical micro-motions, vibration and rotation, in millimeterwave SAR and presented that the SAR images of rotating targets showed a smearing phenomenon [8]. In [9], it was shown that the SAR image from the rotating blades of a hovering helicopter consists of a set of ghost images, which have the form of periodically repeated point spread functions. In [10], Li analyzed the influence of typical target micromotions on SAR images, azimuth resolution limit, ground moving target indication (GMTI), and MTI, and reported several types of image characteristics including gray strips, ghost points, and fences.…”

Section: Introductionmentioning

confidence: 99%

High-Resolution SAR Imaging Characteristics for Multiple Scattering of Rotating Targets

Wang,

Qiu,

Wen

2024

IEEE J. Sel. Top. Appl. Earth Observations Remote Sensing

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The rotation of targets in high-resolution synthetic aperture radar (SAR) images results in complex and nonlinear micro-Doppler modulation of SAR returns, exhibiting distinct and diverse imaging characteristics under different conditions. This poses challenges to image interpretation, target detection and recognition. This study establishes signal models for single and multiple scattering of rotating targets in high-resolution spaceborne SAR and, in conjunction with the processing procedures of range doppler algorithm (RDA), derives the azimuth bandwidth and the conditions for azimuth frequency aliasing caused by rotation. Quantitative analysis of the errors introduced by target rotation in various signal domains is performed, takeing into account the stationary phase point offset, the rotationinduced range migration correction error (RMCE), and the change of azimuth phase in detail. Additionally, representative signatures of these influences in SAR images are simulated and interpreted and more accurate theoretical models of imaging results are derived. The processing and analysis of both simulation and real measured data validate the correctness of the theoretical derivation in this study and provide support for the interpretation and information extraction of high-resolution SAR rotating targets.

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Section: Introductionmentioning

confidence: 99%

High-Resolution SAR Imaging Characteristics for Multiple Scattering of Rotating Targets

Wang,

Qiu,

Wen

2024

IEEE J. Sel. Top. Appl. Earth Observations Remote Sensing

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“…These may be extracted from both monostatic and bistatic radar providing some interesting advantages in the bistatic case [15], [16], [17].The use of micro-Doppler for target classification has been deeply investigated in recent years [18], and it can be now considered a technology ready to be deployed in commercial devices [19]. Of particular interest in the paper is the analysis of the effect from the rotating rotor blades of an helicopter since the effect on the radar returns depends on the characteristics of the rotor like the blade rotating velocity, blade length and the number of blades [15], [20]. Helicopters parameters of helicopter rotor blades were estimated in [21] with an algorithm based on the Radon transform.…”

Section: Introductionmentioning

confidence: 99%

GNSS based passive bistatic radar for micro-Doppler based classification of helicopters: Experimental validation

Clemente

Parry

Galston

et al. 2015

2015 IEEE Radar Conference (RadarCon)

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This version is available at https://strathprints.strath.ac.uk/51869/ Strathprints is designed to allow users to access the research output of the University of Strathclyde. Unless otherwise explicitly stated on the manuscript, Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Please check the manuscript for details of any other licences that may have been applied. You may not engage in further distribution of the material for any profitmaking activities or any commercial gain. You may freely distribute both the url (https://strathprints.strath.ac.uk/) and the content of this paper for research or private study, educational, or not-for-profit purposes without prior permission or charge.Any correspondence concerning this service should be sent to the Strathprints administrator: strathprints@strath.ac.ukThe Strathprints institutional repository (https://strathprints.strath.ac.uk) is a digital archive of University of Strathclyde research outputs. It has been developed to disseminate open access research outputs, expose data about those outputs, and enable the management and persistent access to Strathclyde's intellectual output. Abstract-The capability of using illuminators of opportunity for target classification is of great interest to the radar community. In particular the alternative use of Global Navigation Satellite System (GNSS) has recently initiated a number of studies that aim to exploit this source of illumination for passive radar. We recently introduced the concept of a GNSS based passive radar for extraction of micro-Doppler signatures from helicopter rotor blades with the aim of identify these kind of targets. In this paper we present the experimental validation of our concept with real data from two different models of helicopter.

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“…Target micromotion is of growing interest to the synthetic aperture radar (SAR) community since it can provide additional and favorable information for SAR image interpretation. Micromotion mainly includes rotation and vibration, and typical SAR micromotion targets include ground/shipborne search antennas for air traffic control/surveillance [1], rotor blades of hovering helicopters [2], vibrating vehicles as well as their tires/engines [3], and walking or running dismounts (i.e. humans) [4].…”

Section: Introductionmentioning

confidence: 99%

“…Conventionally only paired echoes (PEs) or ghost images are revealed in SAR imaging of micromotion targets [2,[6][7][8][9][10][11][12]. PEs arise only in special conditions, e.g., minor amplitude of micromotion.…”

Section: Introductionmentioning

confidence: 99%

Angular extent effect of micromotion target in SAR image by polar format algorithm

Deng

Qin

Wang

et al. 2014

J. of Syst. Eng. Electron.

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Target micromotion not only plays an important role in target recognition but also leads to esoteric characteristics in synthetic aperture radar (SAR) imaging. This paper finds out an interesting phenomenon, i.e. the angular extent effect, in micromotion target images formulated by the polar format algorithm. A micromotion target takes on multiple pairs of paired echoes (PEs) around the true point, and each PE extends for an angle which is exactly equal to the angular extent of the synthetic aperture, regardless of the micromotion frequency. The effect is derived and interpreted by using the characteristics of Bessel functions. Then it is demonstrated by simulation experiments of a target with different micromotion frequencies. The revelation and interpretation of the effect is highly beneficial to micromotion-target SAR image understanding as well as target recognition.

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Imaging the rotor blades of hovering helicopters with SAR

Cited by 13 publications

References 3 publications

High-Resolution SAR Imaging Characteristics for Multiple Scattering of Rotating Targets

High-Resolution SAR Imaging Characteristics for Multiple Scattering of Rotating Targets

GNSS based passive bistatic radar for micro-Doppler based classification of helicopters: Experimental validation

Angular extent effect of micromotion target in SAR image by polar format algorithm

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