Abstract
Airborne Synthetic Aperture Radar (SAR) systems are gaining increasing interest within the remote sensing community due to their operational flexibility and observation capabilities. Among these systems, those exploiting the Frequency-Modulated Continuous-Wave (FMCW) technology are compact, lightweight, and comparatively low cost. For these reasons, they are becoming very attractive, since they can be easily mounted onboard ever-smaller and highly flexible aerial platforms, like helicopters or unmanned aerial vehicles (UAVs). In this work, we present the imaging and topographic capabilities of a novel Italian airborne SAR system developed in the frame of cooperation between a public research institute (IREA-CNR) and a private company (Elettra Microwave S.r.l.). The system, which is named AXIS (standing for Airborne X-band Interferometric SAR), is based on FMCW technology and is equipped with a single-pass interferometric layout. In the work we first provide a description of the AXIS system. Then, we describe the acquisition campaign carried out in April 2018, just after the system completion. Finally, we perform an analysis of the radar data acquired during the campaign, by presenting a quantitative assessment of the quality of the SLC (Single Look Complex) SAR images and the interferometric products achievable through the system. The overall analysis aims at providing first reference values for future research and operational activities that will be conducted with this sensor.
Highlights
Synthetic Aperture Radar (SAR) systems are microwave remote sensors that are mounted on board moving platforms in order to obtain high spatial resolution in the along-track direction by emulating the acquisition mechanism of large-aperture antennas [1,2]
During the campaign, a number of Corner Reflectors (CRs) were deployed within the area illuminated by the radar, and very accurate measurement of their positions through the Differential Global Positioning System (D-GPS) technique was carried out to provide a set of sound reference ground points
In order to limit the effects of the residual errors which are typical of airborne SAR data [20], the AXIS system uses a very precise navigation unit, namely, the Applanix POS-AV510, which contains a Global Navigation Satellite System (GNSS) and an Inertial Measurement Unit (IMU), which is directly connected to the radar module and accommodated on the top of the rack
Summary
Synthetic Aperture Radar (SAR) systems are microwave remote sensors that are mounted on board moving platforms in order to obtain high spatial resolution in the along-track direction by emulating the acquisition mechanism of large-aperture antennas [1,2]. In this case, the technological challenge to face consists of the implementation of advanced acquisition modes, such as ScanSAR [1,2,21,22], TOPS [2,5,22,23], and/or advanced optimization strategies, such as the digital beam-forming on receive technique [24], which are aimed at widening the across-track (XT) coverage achievable with the more conventional Stripmap mode [1,2]. During the campaign, a number of Corner Reflectors (CRs) were deployed within the area illuminated by the radar, and very accurate measurement of their positions through the Differential Global Positioning System (D-GPS) technique was carried out to provide a set of sound reference ground points This allowed a first assessment of the quality of the focused SAR images and the Interferometric SAR (InSAR) products achieved with the AXIS system.
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