Browsing by Author "Hagelberg, Alexander"

Now showing 1 - 8 of 8
  • Thumbnail Image
    ItemOpen Access
    Bistatic multi‐polarimetric synthetic aperture radar coherence investigation using spatially variant incoherence trimming
    (Institution of Engineering and Technology (IET), 2024-12-31) Hagelberg, Alexander; Andre, Daniel; Finnis, Mark
    Synthetic Aperture Radar (SAR) Coherent Change Detection allows for the detection of very small scene changes. This is particularly useful for Intelligence, Surveillance and Reconnaissance as small changes such as vehicle tracks can be identified. Rapidly collecting repeat pass SAR imagery is important in these applications. For space‐borne platforms, such repeat passes may however have significant differences, or baselines. Coherent Change Detection products are reliant on high coherence for good interpretability. This work investigates the sources and levels of incoherence associated with bistatic SAR imagery for a variety of baselines using simulations and measured laboratory data for two ground types. Additionally, spatially variant incoherence trimming is implemented. The paper shows the importance of angle‐dependant backscatter on the coherence of sub‐resolution cell scatterers.
  • Thumbnail Image
    ItemOpen Access
    Combined intensity and coherent change detection with four classes for laboratory multistatic polarimetric synthetic aperture radar
    (Institution of Engineering and Technology (IET), 2024-06-14) Hagelberg, Alexander; Andre, Daniel; Finnis, Mark
    Satellites and drone swarms can be used to collect multistatic Synthetic Aperture Radar (SAR) images. Synthetic Aperture Radar images can be used for Intelligence Surveillance and Reconnaissance. One method is to use Coherent Change Detection (CCD) to identify changes such as objects or tracks in the scene. This paper investigates a two-stage change detector, formed using intensity change and CCD images, extended to laboratory measured multistatic SAR data. A variety of performance metrics are used to quantitatively assess the results. Bistatic results are compared to a variety of multistatic and fully polarimetric results. The improvement in performance of multistatic and fully polarimetric images over bistatic images is shown. Additionally challenges and limitations of using multistatic datasets are highlighted.
  • No Thumbnail Available
    ItemOpen Access
    Dataset "Radar geometries used during the PhD of Alexander Hagelberg"
    (Cranfield University, 2024-08-23) Hagelberg, Alexander; Andre, Daniel
    This excel file contains the co-ordinates used in the experiments of the PhD of Alexander Hagelberg. These trajectories were used in various papers which are listed in the headers.
  • Thumbnail Image
    ItemOpen Access
    Laboratory bistatic synthetic aperture radar coherent change detection investigation
    (IET - The Institution of Engineering and Technology, 2023-08-10) Hagelberg, Alexander; Andre, Daniel; Finnis, Mark
    Synthetic Aperture Radar (SAR) Coherent Change Detection (CCD) allows for the detection of very small scene changes. This is particularly useful for reconnaissance and surveillance as small changes such as vehicle tracks can be identified. In some situations, it is desirable to rapidly collect repeat pass SAR images for use in change detection, and multistatic geometries may facilitate this. Such repeat passes may however have significant baselines, particularly for satellite-based platforms, though CCD products are reliant on high coherence for good interpretability. This work investigates the sources and levels of incoherence associated with bistatic SAR imagery with increasing baselines using simulations and measured laboratory data.
  • No Thumbnail Available
    ItemOpen Access
    Multistatic Synthetic Aperture Radar Phenomenology and Interferometry
    (Cranfield University, 2022-11-22T11:36:33Z) Hagelberg, Alexander
    Synthetic Aperture Radar (SAR) is a remote sensing technique which provides high resolution imagery over large areas of the Earth. Unlike optical imagery, SAR operates in all-weathers, day or night. SAR images provide different information compared to electro-optical imagery and allows interferometry to be performed. Interferometry provides sensitive detection of ground height and of changes on the ground. This project investigates multistatic SAR geometries suitable to swarm radar platform concepts including SAR satellite constellations, as well as the processing of collected data.
  • Thumbnail Image
    ItemOpen Access
    Non-overlapping trajectory Multistatic SAR Coherent Change Detection
    (IET, 2022-04-21) Hagelberg, Alexander; Andre, Daniel; Finnis, Mark
    Synthetic Aperture Radar (SAR) Coherent Change Detection (CCD) allows the detection of very small scene changes but is typically reliant on a high degree of similarity in the radar trajectories, with a small baseline. In the case of multistatic SAR imagery, such as those formed by a constellation of SAR satellites, the radar trajectories may have a greater baseline than those collected by a monostatic system such as an aircraft. This paper investigates the effects of multistatic trajectories on the measured coherence between imagery, and how this relates to the spatial frequency (K-space). In particular, the case where radar platform trajectories are greatly dissimilar, but where the K-space image supports still contains a high degree of overlap, is investigated. This paper uses multistatic SAR collections measured at the Ground Based SAR Laboratory at Cranfield University.
  • Thumbnail Image
    ItemOpen Access
    Polarimetric bistatic SAR image coherence
    (VDE Publishing, 2022-11-10) Hagelberg, Alexander; Andre, Daniel; Finnis, Mark
    Synthetic Aperture Radar (SAR) Coherent Change Detection (CCD) allows the detection of very small scene changes, such as from ground subsidence or vehicle tracks, with applications both civilian and military. This high sensitivity to small changes can mean that differences in collection geometry or in polarisation can lead to significant changes in image coherence. This paper investigates the coherence between different bistatic SAR image geometries and their corresponding spatial frequency supports. It also investigates methods used to model coherence. The investigation employed both simulations and measured multistatic data collected at the Ground Based SAR Laboratory at Cranfield University.
  • Thumbnail Image
    ItemOpen Access
    Polarimetrically augmented Coherent Change Detection three stage detector for laboratory multistatic Synthetic Aperture Radar
    (Cranfield University, 2024-01-19T12:41:39Z) Hagelberg, Alexander
    Paper presentation to the Defence and Security Doctoral Symposium 2023