Acceleration Compensation for Estimation of Along-Track Velocity of Ground Moving Target from Single-Channel SAR SLC Data

Abstract

Across-track acceleration is a major source of estimation error of along-track velocity in synthetic-aperture radar (SAR) ground moving-target indication (GMTI). This paper presents the theory and a method of compensating across-track acceleration to improve the accuracy of along-track velocity estimated from single-channel SAR single-look complex data. A unique feature of the proposed method is the utilisation of phase derivatives in the Doppler frequency domain, which is effective for azimuth-compressed signals. The performance of the method was evaluated through experimental data acquired by TerraSAR-X and speed-controlled and measured vehicles. The application results demonstrate a notable improvement in along-track velocity estimates. The amount of along-track velocity correction is particularly significant when a target has irregular motion with a low signal-to-clutter ratio. A discontinuous velocity jump rather than a constant acceleration was also observed and verified through comparison between actual data and simulations. By applying this method, the capability of single-channel SAR GMTI could be substantially improved in terms of accuracy of velocity, and moving direction. However, the method is effective only if the correlation between the actual Doppler phase derivatives and a model derived from the residual Doppler rate is sufficiently high. The proposed method will be applied to X-band SAR systems of KOMPSAT-5 and -6.

Detecting Moving Target on Ground Based on Its Shadow by Using VideoSAR

“…where Z contains all integers. The minimum N value required to meet the detection of slow moving targets is determined according to Equation (9), and the N-frame difference results are accumulated according to Equation (5). By accumulating the results of multi-interval frame difference, we can simultaneously detect a target moving with different velocities.…”

“…The combing ground moving target indication (GMTI) technique partially enables SAR to detect moving targets. This method extracts some parameters of moving targets from moving bright spots after SAR imaging, such as the along track velocity [5], the variations in traffic [6], etc. However, such a GMTI/SAR technique incurs a significant computational load and has a complex implementation procedure [7][8][9].…”

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“…Synthetic aperture radar-ground moving-target indication (SAR-GMTI), which combines SAR imaging and GMTI technology, has played an important role in the modern radar system. Due to the increase of the spatial degree of freedom, multichannel SAR (MSAR) can address the limit of velocity detection and the strong clutter interference in single-channel SAR [ 3 , 4 ]. It can significantly improve the performance of moving-target detection, especially the ability to detect slow-moving targets.…”

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“…Thus, six papers have been published. Two of the six papers dealt with topics related to optical images [7,8], two with radar image topics [9,10], and two with image fusion topics [11,12].…”

“…Lee et al [8] mapped the forest vertical structure in Seogwipo city, Jeju Island. They used the optical KOMPSAT-3 and L-band radar ALOS-1 PALSAR-1 images for the mapping.…”