A Novel Two-Step Scheme Based on Joint GO-DPCA and Local STAP in Image Domain for Multichannel SAR-GMTI

Abstract

Multichannel Synthetic Aperture Radar Ground Moving Target Indication (SAR-GMTI) has been widely used and get great attention nowadays. Traditional adaptive methods like Space-time adaptive processing (STAP) need to calculate and search the maximum of the test statistic pixel by pixel over a large range of radial velocity, which will cause great computational burden. Non-adaptive methods like Displaced Phase Center Antenna (DPCA) will cause signal loss of moving targets, thereby degrading the performance of moving targets detection and radial velocity estimation. To improve the problem mentioned above, this paper proposes a novel two-step scheme based on Greatest Of (GO)-DPCA and Local STAP. In step I, GO-DPCA utilizes the complex images of the channels with different baselines for joint moving target detection. Then in step II, only the local data of moving targets detected in step I needs to be extracted from the original image domain for clutter suppression and radial velocity estimation simultaneously by STAP. Since the processing gain of moving targets depends on the radial velocity and baseline length, the detection performance of moving targets with different radial velocity can be improved by proposed GO-DPCA compared to conventional DPCA. And considering the moving targets usually distribute sparsely in the scene, step II can avoid most computational burden caused by processing pixel by pixel. Finally, the experimental results of both simulated and acquired data are given to validate the effectiveness of the proposed method. Index Terms-Synthetic Aperture Radar (SAR), ground moving target indication (GMTI), greatest of displaced phase center antenna (GO-DPCA), space-time adaptive processing (STAP).

A Novel Detection Scheme in Image Domain for Multichannel Circular SAR Ground-Moving-Target Indication

“…Based on the four-channel real data collected by the airborne SAR, we compare the detection performance of the proposed method with the DRVC method [ 14 ], the GO-DPCA method [ 11 ], and weighted DPCA [ 34 ].…”

“…In this mode, the echo of the auxiliary antenna has a bistatic effect. After range compression, the echo signals in the sub-aperture received by the reference channel and the channel can be written, respectively, as [ 11 , 35 ]: where is represents the amplitude of the echo, is fast time, and c is the speed of light. The symbol B is frequency bandwidth, is carrier frequency, is the rectangle window, and and denote the synthetic aperture time and center time, respectively, of the sub-aperture.…”

“…The commonly used moving-target detection methods can be divided into two types: single-channel [ 5 , 8 , 9 , 10 ] and multichannel [ 3 , 11 , 12 , 13 , 14 ]. The single-channel moving-target-detection method uses the Doppler shift and Doppler rate characteristics of moving targets in SAR images [ 5 , 9 ].…”

“…Different from the single-channel system, the multichannel system has more spatial degrees-of-freedom in azimuth and can realize clutter suppression, thus improving SCR, which effectively enhances detection and parameter estimation performance for slowly moving targets [ 17 ]. To detect slowly moving targets submerged in the main-lobe clutter spectrum, multichannel methods such as displaced phase center antenna (DPCA) [ 11 , 18 , 19 ], ATI [ 7 , 20 , 21 ], space–time adaptive processing (STAP) [ 12 , 22 ], and robust principal component analysis (RPCA) [ 23 , 24 , 25 ] have been widely developed. DPCA and ATI are sensitive to the inevitable noise and are suboptimal for systems with more than two channels.…”

“…In this paper, four-channel, airborne, X-band data is used to verify the correctness and effectiveness of the proposed method. We compared the detection performance of the proposed method with the DRVC method [ 14 ], the GO-DPCA method [ 11 ], and the weighted DPCA [ 34 ]. The results of measured data verified that the PFA of the proposed method is only 20% that of the comparison method and has better robustness.…”