Abstract
Abstract. Multichannel synthetic aperture radar (SAR) is a significant breakthrough to the inherent limitation between high-resolution and wide-swath (HRWS) faced with conventional SAR. Error estimation and unambiguous reconstruction are two crucial techniques for obtaining high-quality imagery. This paper demonstrates the experimental results of the two techniques for Chinese first dualchannel spaceborne SAR imaging. The model of Chinese Gaofen-3 dual-channel mode is established and the mechanism of channel mismatches is first discussed. Particularly, we propose a digital beamforming (DBF) process composed of the subspace-based error estimation algorithm and the reconstruction algorithm before imaging. The results exhibit the effective suppression of azimuth ambiguities with the proposed DBF process, and indicate the feasibility of this technique for future HRWS SAR systems.
Highlights
Modern remote sensing sets higher requirements on the image resolution as well as the swath width for synthetic aperture radar (SAR) (Currie et al, 1992; Gebert et al, 2009; Krieger et al, 2004; Gebert and Krieger, 2009)
The primary goal of this paper is to demonstrate the effectiveness of digital beamforming (DBF) technique on the dual-channel spaceborne SAR mode, providing an approach for future high-resolution and wide-swath (HRWS) SAR systems with more channels
The practical 1877.1 Hz pulse repetition frequency (PRF) leads to a separation of 2.015 m between two equivalent phase centers
Summary
Modern remote sensing sets higher requirements on the image resolution as well as the swath width for synthetic aperture radar (SAR) (Currie et al, 1992; Gebert et al, 2009; Krieger et al, 2004; Gebert and Krieger, 2009). Multichannel SAR has been proposed to obtain high-resolution and wide-swath (HRWS) imaging simultaneously, by splitting the antenna into multiple receive channels in azimuth. Low PRF is transmitted to obtain an unambiguous wide swath, echoes of multiple receivers are combined to improve the azimuth resolution and eliminate azimuth ambiguities. The feasibility of this mode has been verified by TerraSAR-X and AlOS-2 spaceborne SAR and airborne F-SAR data. Previous study achieved good applications of DBF on multichannel SAR imaging They applied correlation method (Liu et al, 2013) to estimate the channel mismatches in DBF, with a little deficiency of not considering other estimation algorithms. There remains a necessary step to complete the spaceborne experiment of error estimation with the OSM
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