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Synthetic Aperture Radar Interferometry (InSAR) allows the generation of Digital Elevation Models (DEMs) exploiting the phase difference (interferogram) of SAR data pairs relevant to the same illuminated area and received by slightly different look angles. Within the processing chain leading from the acquired SAR data pair to the final InSAR DEM, it is necessary to calculate a proper phase offset...
Ionosphere irregularities along the synthetic aperture generate shifts and blurring that cause decorrelation. In this paper it is shown how, by partially focusing SAR images to the height of the ionosphere, it is possible to reduce the ionospheric azimuth effects and increase the coherence. This permits, even in case of turbulent ionosphere, to obtain better accuracies when separating the deformations...
Tandem-L is a proposal for an innovative interferometric radar mission to monitor the Earth system and its intricate dynamics. Important mission objectives are global inventories of forest height and above-ground biomass, largescale measurements of Earth surface deformations due to plate tectonics, erosion and anthropogenic activities, observations of glacier movements and 3-D structure changes in...
We have designed and developed a new airborne Ku-band Doppler radar, called KuROS, to prepare the CFOSAT satellite mission for measuring ocean surface wind and waves. The main characteristics of this new radar are presented, and first results obtained from a campaign held in 2013 illustrated. Both intensity and Doppler information are used to estimate the directional spectra of ocean waves. Radar...
Optronic processing is a promising way to real-time highresolution SAR image formation. Rang migration is inevitable in SAR imaging, especially in the case of highresolution SAR system, range cell migration correction (RCMC) is considered in nature. A solution of RCMC by using optronic processing is presented in this paper. In this optronic solution, most computation is undertaken by optical devices,...
This paper presents a two-dimensional (2-D) generalized omega-K algorithm for high-precision processing of the data of missile-borne Synthetic Aperture Radar (SAR) with constant acceleration. The almost adequate expression of the 2-D spectrum of the echo signal is obtained by the Method of Series Reversion (MSR). Then a 2-D generalized Stolt interpolation is carried out. The proposed algorithm can...
Angular super-resolution performance is the key problem in the field of radar imaging. In this paper, we propose an approach to radar angular super-resolution through deconvolution, which is able to increase the resolution of radar image beyond the limitation of system parameters. It relies on the Bayesian formulation approach that enables to incorporate the prior information about the system and...
The theory of compressed sensing (CS) indicates that the optimal reconstruction of an unknown ISAR signal with intrinsical sparsity can be achieved by solving a sparsity-driven optimization problem. Due to this property, a novel method to construct sparse basis is presented for ISAR image generation. We utilize discrete chirp fourier transform (dcft) and CLEAN to decompose the signal of interest into...
Many parameters are required for the measurement of the sea surface currents and the sea levels simultaneously by the along-track interferometry SAR (AT-InSAR). To estimate the elevation or the sea levels from the signals observed by the AT-InSAR, the method for synthesizing these received signals was developed. To evaluate the estimation method, the ground surface was observed by the cross-track...
In the area of airborne synthetic aperture radar (SAR), motion compensation (MOCO) is a crucial technique employed to correct the SAR data affected by nonlinear platform trajectory during data acquisition. Due to range-azimuth coupling and computational burden consideration, MOCO is usually implemented only with respect to range dependent motion errors, which is adequate for SAR systems of moderate...
For high resolution spaceborne SAR system, the errors caused by straight trajectory assumption and stop-go approximation cannot be ignored. In this paper, an algorithm is proposed to compensate the above errors. First, a novel modified hyperbolic range equation (MHRE) is introduced to describe the satellite's orbit which is more precise than the traditional hyperbolic range equation (THRE). Then,...
Near-space Synthetic Aperture Radar (SAR) possesses useful features such as High-Resolution Wide-Swath (HRWS) and high revisiting frequency etc., which are difficult for the conventional SAR, e.g. spaceborne and airborne SAR, to simultaneously provide. Slow-speed SAR is introduced to solve the contradiction between high resolution and wide swath of Near-space SAR and a frequency domain algorithm based...
In space-borne azimuth multi-channel SAR, the antenna phase center spacing should be measured precisely to obtain the reconstruction filters. In this paper, a data-based onboard estimation method of antenna phase center spacing in spaceborne multi-channel SAR system is proposed. Firstly, the principle of data-based onboard estimation is presented, then the estimation method in details is described...
As having the imaging ability of area in front of flight direction, forward-looking synthetic aperture radar (SAR) has become a hot topic in areas of SAR research. Nevertheless, the currently exploited imaging algorithms of forward-looking SAR suffer from poor azimuth resolution induced by limited azimuth aperture length. To address this challenge, we develop a super-resolving imaging algorithm for...
The displaced phase centre multiple azimuth beams (DPC-MAB) synthetic aperture radar (SAR) can realize wide swath imaging with high azimuth resolution, but it has strict requirement on the pulse repetition frequency (PRF). When actual PRF deviates from the ideal PRF, non-uniform azimuth sampling will arise and then seriously interfere with SAR imaging. This paper proposes a novel reconstruction method...
An automatic DPCA technique is presented for SAR Ground Moving Target Indication (GMTI). We note that there exists a shift and a phase difference between the images from two channels. Therefore, SAR-GMTI can be implemented in the following steps: Image registration, phase compensation, image subtraction, and CFAR detection. In our technique, these steps are carried out automatically, and thus no precise...
This paper proposes an algorithm for multi-channel SAR ground moving target detection and estimation using the Fractional Fourier Transform(FrFT). To detect the moving target with low speed, the clutter is first suppressed by Displace Phase Center Antenna(DPCA), then the signal-to-clutter can be enhanced. Have suppressed the clutter, the echo of moving target remains and can be regarded as a chirp...
Ground moving target detection (GMTD) for squint synthetic aperture radar (SAR) is a more challenging task than that of the broadside SAR. The severe range and azimuth coupling induced by the squint mode combined with the unknown motion parameters makes the problem of indicating the moving targets more involved. In this paper, a novel ground moving target detection method for squint SAR is proposed...
An efficient approach to achieve ground moving target indication (GMTI) for synthetic aperture radar (SAR) is to use the Monopulse-SAR system. This paper examines the statistics of monopulse ratio (MR) for SAR/GMTI model when complex Gaussian clutter-plus-noise is considered. The probability density function (pdf) of MR is analyzed in detail. Especially, the conditional likelihood function of MR under...
Airborne SAR imaging processing needs to estimate motion error to compensate non-ideal trajectory. In this paper, a subaperture imaging scheme for wide azimuth beam airborne SAR systems is proposed. First, the motion error is estimated from the subaperture data and the modified range migration algorithm is applied to obtain the coarse focused image, whose azimuth resolution corresponds to the subaperture...
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