Subaperture Imaging Algorithm for Squinted Automotive FMCW SAR Based on CLOSI-Omega-K

Abstract

Due to the short duration of automotive frequency-modulated continuous-wave (FMCW) synthetic aperture radar (SAR), targets located at the edge of the imaging scene are often distorted in the SAR image, rendering conventional imaging algorithms ineffective. Moreover, the under-utilization of the supported area in the wave-number domain significantly compromises image quality. To address these challenges, this paper presents a modified Omega-K subaperture imaging algorithm based on cross-line-of-sight interpolation (CLOSI) for the squinted automotive FMCW SAR. CLOSI ensures the optimal utilization of the wave-number spectrum, thereby guaranteeing superior image quality. By compensating for the phase-wave-number variation ratio, the problem of point target position aliasing arising from the azimuth width of the imaging scene exceeding the length of the synthetic aperture is solved. Integration with SPECAN processing enables the final imaging results to be focused in both the range position and azimuth wave-number domains. This eliminates the need for zero padding, thereby enhancing processing efficiency. Finally, the feasibility of the proposed algorithm is verified by point target simulation experiments. The imaging performance indicators, such as the peak side lobe ratio (PSLR) and the integral side lobe ratio (ISLR), are close to their theoretical values of -13.24dB and -9.80dB, respectively, demonstrating the effectiveness of the proposed algorithm.

Keywords

• Squinted automotive frequency-modulated continuous-wave synthetic aperture radar (FMCW SAR)
• subaperture imaging
• cross-line-of-sight interpolation (CLOSI)
• SPECAN processing