Abstract
Calibration using corner reflectors is an effective way to estimate the distortion parameters of hybrid compact polarimetric (HCP) synthetic aperture radar (SAR) systems. However, the existing literature lacks a discussion on the inconsistency of the amplitude and phase coefficients between measured scattering vectors of different corner reflectors. In response to this problem, this paper first proves that this inconsistency will seriously deteriorate the estimation accuracy of polarimetric distortion parameters. Based on the optimization algorithm, two calibration schemes for simultaneously estimating the traditional distortion parameters and the amplitude/phase coefficients are proposed while ignoring crosstalk (ICT) and considering crosstalk (CCT). In the process of distortion parameter estimation, the idea of “optimizing while compensating” is adopted to eliminate the problem of uneven echo intensity. Simulation results show that both schemes can eliminate the influence of the inconsistency of amplitude and phase coefficients, and estimate distortion parameters accurately. When the received crosstalk level is lower than −30 dB, the ICT scheme can accurately estimate polarimetric distortion parameters. The CCT scheme has a wider application range of crosstalk and can work well when the crosstalk level is lower than −20 dB, but it also has a higher requirement for the signal-to-clutter ratio (SCR). When SCR is greater than 35 dB, the CCT scheme yields higher estimation accuracy than the ICT scheme. In addition, the effectiveness of the calibration schemes is verified based on the L-band measured data acquired by the Aerospace Information Research Institute, Chinese Academy of Sciences.
Highlights
Introduction published maps and institutional affilRecently, more and more researchers have begun to turn their attention to HybridCompact Polarimetric (HCP) Synthetic Aperture Radar (SAR), and the research covers many aspects, such as system architecture [1], interpretation algorithms [2,3,4,5], and the potential for the technology in remote sensing applications [6,7,8], etc
We simulated the estimation error when each distortion parameter changes with crosstalk under the T2D calibrator configuration
It is concluded that the worst-receiving crosstalk levels applicable to the ignoring crosstalk (ICT) and the considering crosstalk (CCT) scheme are −30 dB and −20 dB, respectively
Summary
Compact Polarimetric (HCP) Synthetic Aperture Radar (SAR), and the research covers many aspects, such as system architecture [1], interpretation algorithms [2,3,4,5], and the potential for the technology in remote sensing applications [6,7,8], etc. HCP can only acquire partial polarimetric information of the ground target compared to quad-polarimetric system, it can overcome shortcomings such as narrow imaging width, high pulse repetition frequency, and complicated system design due to additional channel gain [9]. These advantages reduce the cost of hardware design, which is consistent with the goal of payload miniaturization. RISAT-1 [12] in India, ALOS-2 [13] in Japan, and RADARSAT Constellation Mission iations
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