Abstract
Geosynchronous synthetic aperture radar (GEO SAR) has great potentials in ship surveillance due to its high time resolution and wide swath coverage. However, the remote slant range will result in a very low signal-to-noise ratio (SNR) of echoes that need to be enhanced by long-time coherent integration. The generalized Radon-Fourier transform (GRFT) can realize the coherent integration of moving target under long integration time by jointly parameter searching along range and velocity directions. Unfortunately, in GEO SAR, the very large slant range and long synthetic aperture will cause the curved synthetic aperture trajectory and non-negligible signal round-trip delay, leading to the failure of the traditional slant range and GRFT signal model for moving targets. This paper proposes an improved GRFT-based approach to realize the detection and imaging of moving ship targets in GEO SAR. Firstly, the accurate slant range for moving ship targets is constructed and the GRFT signal is redefined considering the curved trajectory and signal round-trip delay in GEO SAR. Then, GRFT responses to different motion parameters are analyzed. The procedures of moving ship targets detection and imaging in GEO SAR are presented through the detection with coarse-searched motion parameters in GRFT and the following imaging with fine-searched motion parameters based on minimum entropy. Finally, computer simulations verify the proposed GRFT-based method.
Highlights
As a kind of all-day, all-weather, high-resolution remote sensing techniques, synthetic aperture radar (SAR) becomes one of the main approaches of ship surveillance [1,2]
This paper proposes an improved generalized Radon-Fourier transform (GRFT)-based approach to realize moving ship targets detection and imaging in Geosynchronous synthetic aperture radar (GEO SAR)
Due to the characteristics of the slant range model, the existing GRFT cannot be applied to GEO SAR directly, resulting in the GRFT needing to be redefined to make it suitable for the signal integration of moving ship targets
Summary
As a kind of all-day, all-weather, high-resolution remote sensing techniques, synthetic aperture radar (SAR) becomes one of the main approaches of ship surveillance [1,2]. Moving ship detection and estimation can be realized without sea clutter suppression by single-channel SAR scheme, which can be divided into short-time and long-time integration. This paper proposes an improved GRFT-based approach to realize moving ship targets detection and imaging in GEO SAR. The main contributions are as follows: the accurate slant range model for moving ship targets in GEO SAR is established; based on the slant range model, the GRFT-based signal integration method is modified and the processing for moving ship targets detection and imaging is given. The processing of moving ship targets detection and imaging in GEO SAR, which can be summarized as detection with motion parameters’ coarse searching in GRFT and the following imaging with fine-searched motion parameters, is given.
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