Browsing by Author "Welsh, Richard"

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    Laboratory multistatic 3D SAR with polarimetry and sparse aperture sampling
    (Wiley, 2024-01-01) Welsh, Richard; Andre, Daniel; Finnis, Mark
    With the advent of constellations of SAR satellites, and the possibility of swarms of SAR UAV's, there is increased interest in multistatic SAR image formation. This may provide advantages including allowing three-dimensional image formation free of clutter overlay; the coherent combination of bistatic SAR geometries for improved image resolution; and the collection of additional scattering information, including polarimetric. The polarimetric collection may provide useful target information, such as its orientation, polarisability, or number of interactions with the radar signal; distributed receivers would be more likely to capture any bright specular responses from targets in the scene, making target outlines distinct. Highlight results from multistatic polarimetric SAR experiments at the Cranfield University GBSAR laboratory are presented, illustrating the utility of the approach for fully sampled 3D SAR image formation, and for sparse aperture SAR 3D point-cloud generation with a newly developed volumetric multistatic interferometry algorithm.
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    Laboratory multistatic polarimetric 3D SAR
    (IET, 2023-02-07) Andre, Daniel; Welsh, Richard; Finnis, Mark
    With the advent of constellations of SAR satellites, and the possibility of swarms of SAR UAV's, there is increased interest in multistatic SAR image formation. This may provide advantages including allowing three-dimensional image formation free of clutter overlay; the coherent combination of bistatic SAR geometries for improved image resolution; the collection of additional scattering information, including polarimetric. The polarimetric collection may provide useful target information, such as its orientation, polarizability or number of interactions with the radar signal; distributed receivers would be more likely to capture any bright specular responses from targets in the scene, making target outlines distinct. Highlight results from multistatic polarimetric SAR experiments at the Cranfield University GBSAR laboratory are presented, illustrating the utility of the approach.
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    Laboratory multistatic polarimetric sparse aperture 3D SAR investigation
    (Institute of Acoustics, 2023-12-31) Welsh, Richard; Andre, Daniel; Finnis, Mark
    Synthetic Aperture Radar (SAR) is a coherent technique that produces high quality imagery, with a finer cross-range resolution than would be possible with a stationary antenna. Radar pulses from multiple points along a flight path are combined, with return time and phase recorded for each pulse. This technique can be used to produce multidimensional 3D SAR images, with scatterers otherwise overlaid in range and azimuth separated out in height.
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    Multistatic 3D SAR imaging with coarse elevation and azimuth sampling
    (IEEE, 2022-11-10) Welsh, Richard; Andre, Daniel; Finnis, Mark
    It is advantageous to produce Synthetic Aperture Radar (SAR) renderings in three dimensions as these allow the separation of features in height, providing additional target information. A Nyquist sampled 2D SAR aperture produces high quality 3D imagery, however the large scanning time and data storage requirements make this method impractical for use in many scenarios. This paper investigates the formation of 3D target renderings from sparsely sampled 2D aperture Multistatic SAR geometries. The investigation employed both simulations and measured multistatic data collected at the Ground Based SAR (GBSAR) Laboratory at Cranfield University.
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    Volumetric interferometry for sparse 3D synthetic aperture radar with bistatic geometries
    (Institution of Engineering and Technology (IET), 2023-06-25) Welsh, Richard; Andre, Daniel; Finnis, Mark
    Synthetic Aperture Radar (SAR) renderings in 3D provide additional target information when compared to 2D by separating out features overlaid in height. However, the required 2D SAR aperture, when Nyquist sampled, necessitates large scanning times that would be impractical for most realistic collections. This research has developed a novel volumetric approach to sparse aperture 3D SAR imaging, that is applicable to bistatic SAR near-field geometries, a generalization of far-field cases. This approach is first demonstrated in simulation and then applied to a measured scene containing a model vehicle target, producing sub-Nyquist sampled 3D SAR renderings.