Abstract
In a dual-channel circular synthetic aperture radar (CSAR) and ground moving target indication (GMTI) system, the antenna baseline is not parallel with the flight path due to a yaw angle. The angle causes a varying group-phase shift between the dual-channel signals and therefore degrades the correlation between the image pair. Therefore, the group-phase shift needs to be removed before channel equalization. To resolve the problem, the interferometric phase term was deduced and analyzed based on the geometry of a dual-channel CSAR system. Then, the varying phase term with respect to the Doppler frequency and the varying group-phase shift over the range were compensated for in the channel registration. Furthermore, blind channel equalization, including two-dimensional calibration and amplitude equalization, was applied to eliminate the amplitude and residual phase differences between the channels. Finally, the amplitude image obtained using a displaced phase center antenna (DPCA) was multiplied by the phase image obtained with along-track interferometry (ATI) to detect moving targets. The experimental results verified the effectiveness of the method for both uniform and non-uniform clutter suppression.
Highlights
Synthetic aperture radar (SAR) combined with ground moving target indication (GMTI) [1]technology has been extensively studied in remote sensing
For the dual-channel circular SAR (CSAR)/GMTI system, the image geometry had a significant impact on the moving target indication
We proposed a modified GMTI method that included moving target indication
Summary
Synthetic aperture radar (SAR) combined with ground moving target indication (GMTI) [1]. The carrier yaw in the dual-channel CSAR geometry causes group-phase shift [5] between the CSAR image pair Both the amplitude and phase differences affect the image correlation and might give rise to residual components after clutter suppression. We deduced phase differences of the dual-channel signals pair. Inthe thisCSAR study,imaging we deduced the phase differences ofathe dual-channel signals incompensate the CSAR imaging varying phase differences between channels. We proposed a phase factor to efficiently compensate for the varying phase differences registration, channel equalization, andMTI a DPCA plus ATI method, was utilized toregistration, suppress the channel clutter, between channels.
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