Research On High Squint Airborne SAR Moving Target Imaging Algorithm

Synthetic Aperture Radar (SAR) is a very important remote sensing tool. SAR has thecharacter of all-day and all-weather imaging with the image quality regardless of the weatherconditions. Different from those traditional stationary target imaging algorithms, this paper intendto research on moving target imaging algorithm via high squint SAR. It has capability to imagingmoving targets. Moreover squint mode SAR is particularly suitable for battlefield reconnaissanceand hidden object detection, also this mode can visit desired zones repeatedly by changing the beampointing. Most important the high squint mode can provide a safety and hidden environment forairborne platforms by detecting target in advance. This system is often equipped on the fighters andbombers. Given these advantages the moving target imaging technology via high squint has a wideuse in military and civil filed.This paper aim to develop a moving target imaging Algorithm via high squint SAR based onRDA, the main content is organized as follows:(1) Introduced some basic theories about SAR system and then established SAR signal modelby analyzing the characteristic of SAR system. Then studied the effect of moving targets on SARimages through stationary targets imaging algorithm.(2) This paper investigated the moving target imaging algorithm with known and unknownspeed of moving target in side-looking mode. For the case of speed unknown, this paper use thekeystone transformation to correction range migration, and then use the correlation function andminimum entropy criterion to estimate the Doppler center and Doppler frequency respectively, andultimately realized the SAR imaging of moving targets in unknown speed condition.(3) Studied the characteristics of high squint SAR system, then established the appropriategeometric model according to squint SAR system. Traditional algorithm has the deficiencies inimage quality and processing speed. In this paper, a keystone transform based on time domainscaling principle has been taken to improve processing speed and more accurate range cellmigration equation to improve image quality.