SAR Imaging of a Moving Target

Abstract

In the proposed work new synthetic aperture radar Doppler frequency. The position of bright points along the geometry named Generalized Inverse Synthetic Aperture Radar radar line of sight (LOS) axis (range axis) is given by time (GISAR) geometry is addressed. A new three-dimensional (3-D) analysis while their position on the cross-range axis is model of deterministic components of GISAR trajectory signals provided by Doppler frequency analysis. The range-Doppler with stepped frequency modulation is suggested. 3-D GISAR technique is based on the assumption that the Doppler geometry is described by means of the analytical geometry. The geometry and kinematics of the object and GISAR observation firequency shift of each scatterer ls constant during the system are described in separate 3-D Cartesian coordinate processing time. This can be valid assumption for low cross system. The stationary objects are presented in 3-D regular grid range resolution and for targets moving along regular of isotropic point scatterers, relatively moving with respect to trajectories. However, this is no longer valid for a target GISAR system at the velocity of the SAR carrier. The SAR undergoing irregular rotation motions, like tanks at battlefield carrier is considered unmoving placed in the origin of the where Doppler frequency shift variation during processing coordinate system of observation. The stationary targets are time induce a spreading effect of scatterers' contributions. In moving at the complex velocity equal to the geometrical sum of such a case, the use of some joint time-frequency processing the target velocity and SAR carrier velocity. The analytical is obvious [6, 10]. This allows observing the evolution of expressions to compute the range distance to point scatterers of the stationary scene and moving targets are derived. The image Doppler information durmig recordmig time. The main reconstruction procedure includes both range and azimuth advantage of such a technique is its ability to concentrate a compression: cross correlation technique to GISAR signal to wideband signal, like a chirp, while it spreads noise [7, 12]. realize range compression and short time frequency transform The problem of airborne side view ISAR imaging of ship to realize azimuth compression. A range alignment and an targets is examined in [8], which results in a robust autofocusing technique are applied to GISAR signal. To processing scheme including target motion estimation and illustrate the capability of the 3-D ISAR signal model numerical correction, optimal processing time and duration estimation experiment is implemented. and target shape extraction.In the recent publications there is a lack of description of 3-I. INTRODUCTION D geometry of the GISAR scenario with application of Synthetic aperture radar (SAR) imaging is a signal stepped frequency emitted signals combined with crossprocessing algorithm for surveillance and mapping of Earth correlation and time-frequency transform procedures for and ocean surface. SAR is a technique using t...

SAR imaging of moving targets using polynomial Fourier transform

“…Then, it would be very interesting to apply the phase differentiation (higher-order ambiguity function) with the nonlinear optimisation approach proposed in [34] in order to achieve two goals: focused radar image for multicomponent signals with reduced calculation complexity. In addition, the proposed approach can be applied to the newly proposed SAR systems with generalised inverse synthetic aperture radar geometry [35].…”

Research on Turning Motion Targets and Velocity Estimation in High Resolution Spaceborne SAR

“…4. Obtain the refocused ROI target sized M × N in time domain by applying azimuth Fourier transform (FFT); 5. measure and calculate the displacement of azimuth position caused by target motion; 6. calculate the radial velocity V y according to Equation (9) and Equation; 7. The azimuth velocity V x is calculated by the compensation phase curve and the radial velocity estimation results combined with Equation (7); and, 8. calculate the amplitude V m and the direction θ m of the velocity through the radial velocity V y and the azimuthal velocity V x .…”

“…There are also literature analyses of the imaging effect of moving targets with acceleration [7], that is, the third phase error and the asymmetric distortion of the image. Another part of the literature analyzes the influence of the complex motion of the target, such as the rotation motion of the target itself [8], three-dimensional motion [9,10], vibration, and other Sensors 2020, 20, 2201 2 of 19 fretting forms [11]. There are also a part of literatures that introduces the influence of ship fretting, such as the ship's three-dimensional swing, including roll, pitch, yaw, and so on [12,13].…”

Simulator-defined Radar Countermeasure System (Sim-dRCS) Proof of Concept for Deception in Air Defense at Sea

“…This duality is mentioned because it helps to explain the ISAR operational principle. 14 Technically, ISAR systems employ the concept of coherence, which means that the phase or frequency information of the return echoes are processed together with the amplitude of the return signal. 15 This enhanced reflectivity information is handled by a digital signal processor.…”