Deceptive jamming against synthetic aperture radar (SAR) receives intensive interests during the past decade. However, it is still a challenging task to design a jamming method that is competent both in focus capabili...
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Deceptive jamming against synthetic aperture radar (SAR) receives intensive interests during the past decade. However, it is still a challenging task to design a jamming method that is competent both in focus capability and in computational efficiency, especially in the case where jammer is confronted with SAR with significant squint angle and long synthetic aperture. In this paper, we propose an inverse omega-k algorithm and present an accurate and an approximate implementation scheme of the algorithm. The accurate scheme can achieve full focus with no regard to the squint angle and synthetic aperture of radar. Its computations include fast Fourier transform (FFT), Stolt interpolation, and complex multiply. Advantage of computational efficiency can be achieved under assumption that the support region of radar can be crudely evaluated a priori so that the most time-consuming Stolt interpolation can be done offline. The support region is determined by carrier frequency and bandwidth of radar signal, pointing direction, and azimuth beam width of radar antenna. For the case in which the support region of radar is not available to jammer beforehand, the approximate scheme is a remedy. By substituting the Stolt interpolation with Chirp-Z transform (CZT), the approximate scheme is readily fit for parallel computation and hence appealing for its high efficiency. However, the focus criterion exerts a limitation on range scale of electromagnetic deception when the squint angle of SAR is large. Both implementation schemes are verified by simulation results.
Due to a long coherent processing interval, moving targets are severely smeared in the UHF-band synthetic aperture radar (SAR) imagery. This further results in a low signal-to-clutter-and-noise ratio, which might lead...
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Due to a long coherent processing interval, moving targets are severely smeared in the UHF-band synthetic aperture radar (SAR) imagery. This further results in a low signal-to-clutter-and-noise ratio, which might lead to an unacceptable false-alarm rate in multichannel ground moving target indication. A method of moving target screening is presented in this letter, which serves to determine whether the target detected by a constant false-alarm rate detector is a real moving target. An inverse omega-k algorithm is implemented, which can recover the Doppler phase history of any isolated target within a clutter-suppressed omega-k SAR image. The recovered data are again processed into a subimage by a simple range-Doppler algorithm. Then, the subimage is refocused by azimuth autofocus processing. The sharpness of the subimage will not change after refocusing if it only contains stationary targets;otherwise, the sharpness will significantly improve. We can eliminate a false moving target by detecting this change. The proposed method is demonstrated on simulated and real multichannel UHF-band SAR data.
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