Ground Moving Target Imaging and Analysis for Near-Space Hypersonic Vehicle-Borne Synthetic Aperture Radar System with Squint Angle

Abstract

Near space is the key to integrating “sky” and “space” into the future. A synthetic aperture radar (SAR) that works in this area would initiate a technological revolution for remote sensing applications. This study mainly focused on ground moving target imaging (GMTIm) for a near-space hypersonic vehicle-borne SAR (NS-HSV-SAR) with squint angle. The range history, parameter coupling, and Doppler ambiguity of the squint-looking NS-HSV-SAR are more complicated than traditional side-looking airborne or space-borne SARs. Thus, a precise range model is presented on the basis of phase error analyses. Then, all potential distributions of echo’s azimuth spectrum are derived, and a GMTIm method is proposed on the basis of a detailed analysis of the echo characteristics. The proposed method consists of three steps. Firstly, a prior information-based pre-processing function was created to decrease the Doppler ambiguity and range migration effects. Secondly, a blur matched keystone transform was developed to correct the residual range walk migration. Thirdly, a time-saving chirp Fourier transform was investigated for azimuth focusing. Implementation considerations, including the curvilinear trajectory of the NS-HSV-SAR, multiple moving target imaging, and applicability and limitation of the method, are discussed. Finally, simulation results are presented to validate the effectiveness of the proposed method.

Non‐adaptive space‐time clutter canceller for multi‐channel synthetic aperture radar

“…2a to verify the accuracy of (2). Similar to the phase error analysis in SAR [14] and existing studies [15][16][17], the farther from the centre of the detected scene, the larger the phase error of the range history caused by the Taylor series expansion is. Thus, two targets with velocity of (−9, −12, 0) m/s and (9, 12, 0) m/s located at the edge of an interested scene are selected.…”

“…The fourth approximation is that the residual range migration after performing the proposed HCP compensation and DEP compression functions is recognised to be ignored, as shown in (9). Actually, the above-mentioned first three approximations are true only if the total phase error they cause is not higher than the intolerable level, that is, π/4 in general [14][15][16][17], and the fourth approximation is true only if the residual range migration is small than half of the range resolution [14,17]. For clutter/targets with different initial positions and velocities, the residual phases vary after the proposed HCP compensation function and the DEP compression function are performed.…”

“…represents the bandwidth of the transmitted signal. It is difficult to obtain the analytical scope of target position and velocity from (16) and (17), because these two inequalities are related to the selection of radar system parameters. However, for a given radar system, we can easily determine the maximum velocity of the target and the maximum distance between the target and reference range, as (16) and (17) become the one-dimensional inequality.…”

Ground moving target focusing and motion parameter estimation method via MSOKT for synthetic aperture radar

“…However, if a large scope or a small step size is set, the computational complexity of the proposed method will increase. Hence, prior information (such as road position information, open street map, speed data, and legal maximum velocity in the road) is utilised to determine the search scope of [31]. Then, an appropriate small search scope can be obtained because using existing traffic information can considerably improve the processing efficiency [32, 33].…”

An Interrupted Sampling Scattered Wave Deception Jamming Method against Three-Channel SAR GMTI

“…Synthetic aperture radar ground moving target indication (SAR GMTI) is able to get high resolution images of sensitive areas and information of moving targets at all-time under all-weather condition [1][2][3][4]. Displaced phase center antenna (DPCA) and along track interferometry (ATI) are a type of three-channel SAR GMTI.…”