Two Dimension Digital Beamforming Preprocessing in Multibeam Scansar

Abstract

Abstract-The novel multibeam ScanSAR takes advantage of the displaced phase center multiple azimuth beam (DPCMAB) imaging scheme and intra-pulse beam steering in elevation in ScanSAR to achieve the high-resolution ultra-wide-swath imaging capacity. This letter proposes an innovative two-dimensional (2D) digital beamforming (DBF) space-time preprocessing approach for multibeam ScanSAR. According to echo proprieties of such imaging scheme, both azimuth ambiguity and range ambiguity problems should be resolve before a conventional ScanSAR imaging processor. After range compressing in each receive channel, a 2D DBF processor is carried out in the range-Doppler domain. The azimuth DBF operation is adopted to resolve the azimuth nonuniform sampling problem in multichannel SAR systems, while the DBF preprocessing in elevation is carried out to separate echoes from different subswaths corresponding to different sub-pulses. Imaging results on simulated distributed targets validate the proposed 2D DBF preprocessing approach.

SAR Imaging Based on Compressive Sensing via Fractional Fourier Transform

“…Due to its compressed sampling ability, compressed sensing has found many attractions in radar remote sensing and branched out to many new fronts. R. Baraniuk et al proposed the radar imaging system based on CS for the first time and a high resolution imaging method is presented in for SAR sparse targets reconstruction based on CS theory [7][8][9][10][11][12][13][14][15]. In the above researches, it has been shown that a successful recovery of a compressible signal depends on the presence of sparse dictionary and these works have made a great contribution to the future research of radar signal processing.…”

MIMO SAR Using Orthogonal Coding: Design, Performance Analysis, and Verifications

“…Spotlight obtains very fine resolution while it cannot observe the earth continuously in azimuth [2]. Other techniques including wide swath imaging via elevation and azimuth multiple beams [3,4] or azimuth digital beam forming [5][6][7] and high resolution wide swath (HRWS) imaging via multidimensional waveform encoding are proposed [8], while they cause the system complexity ascension, reliability reduction, or signal processing difficulty increasing.…”

Joint Two-Dimensional Ambiguity Resolving Based on Space-Time Filtering for MIMO-SAR

“…To obtain wide swath coverage and high resolution, one can utilize two-dimensional array to transmit and receive SAR signals and then resolve the range and azimuth ambiguity [13]. However, this method makes range point target downlooking angle as range steer vector in approximate treatment and does not consider the changing of the downlooking angle with the azimuth time.…”