Space-based bistatic GMTI using low resolution SAR

IET Radar, Sonar & Navigation

2014

This study develops a methodology for analytically predicting the detailed smear signature morphology of surface targets with arbitrary motion in spotlight synthetic aperture radar (SAR) imagery. The radar sensor is assumed to move with constant speed and heading on a level flight path with broadside imaging geometry. Cases of uniform target motion exhibit morphology of simply curved smear shapes, as has been reported previously. However, the present analysis shows that nonuniform target motion can cause complicated smear shapes in spotlight SAR imagery. Specifically, the method of stationary phase is applied to local subaperture SAR images to yield analytic non-parametric expressions for the morphology of smear signatures within spotlight SAR imagery for surface targets with arbitrary motion trajectories. This predictive capability offers the potential of extracting some characteristics of true target motion based upon the induced SAR smear signatures alone.

Section: Introductionmentioning

confidence: 99%

Smear signature morphology of surface targets with arbitrary motion in spotlight synthetic aperture radar imagery

IET Radar, Sonar & Navigation

2014

“…14(b). This result provides another example of the strong effects of acceleration on signature morphology, as perpetrated through the relatively large value of κ 0 via the κ 0 w 0 cos(φ 0 ) tanh(ψ(τ s )) term in (26) for y(τ s ). Fig.…”

Section: Hyperbolic Tangent Speed Targetsmentioning

confidence: 86%

“…The general properties of moving target signatures in SAR imagery have been developed by a number of researchers [10]- [13]. Some researchers have developed specific methods for detecting and refocusing the smears resulting from moving targets [14]- [26] and for estimating their motion parameters [27]- [32]. Jao [33] revealed that moving targets give curved signatures in SAR imagery, which are related to range migration effects [34], [35].…”

Section: Introductionmentioning

confidence: 99%

Signature Morphology Effects of Squint Angle for Arbitrarily Moving Surface Targets in Spotlight Synthetic Aperture Radar

IEEE Trans. Geosci. Remote Sensing

2015

Abstract-This investigation examines the phenomenology effects of the squint angle on the morphology of moving target smears in spotlight synthetic aperture radar (SAR). This analysis includes both the smears resulting from standard image formation applied to simulated radar measurements as well as the theoretical predictions for the central contours of the signatures. In particular, this paper generates the down-range and cross-range components of the predicted central 2-D contours of mover signatures, including the locations of the cross-range offsets. The analytics for squinted geometry include additional contributions in the signature contour equations that do not arise for the case of broadside imaging. These terms can affect the overall contour morphology, particularly in terms of shape and extent. Numerous examples are presented to demonstrate that the signature prediction equations yield excellent agreement with standard image formation with simulated radar data. Therefore, this analysis can provide an effective tool in predicting the shape, extent, and location of smears due to arbitrarily moving surface targets for squinted spotlight SAR.

“…In particular, a number of researchers [1][2][3][4] investigate the general features of mover smears. Other researchers [5][6][7][8][9][10][11][12][13][14][15][16][17] examine the detection and focusing of moving target signatures. Additional researchers [18][19][20][21][22][23] analyze techniques for improving the detection and estimation of moving targets in SAR imagery.…”

Section: Introductionmentioning

confidence: 99%

Insights into the complicated SAR signature shapes induced by braking targets

Algorithms for Synthetic Aperture Radar Imagery XXV

2018

This investigation considers the shapes of synthetic aperture radar (SAR) imagery signature smears that are caused by surface targets that perform braking maneuvers during the SAR collection time. It is known that such maneuvering target signatures can have a wide variety of two-dimensional (2D) shapes, as opposed to the simpler parabolic signatures that are induced by constant velocity targets. The current paper examines the theoretical properties of these 2D signature shapes for cases in which the specific parameters of the target braking maneuver temporal profile are varied, including the rate at which the target decreases speed, the total amount of speed change, and the speed transition time within the SAR collection interval. Furthermore, the current investigation yields new insights regarding the complicated SAR signature shapes that are indicative of targets undergoing such braking maneuvers. This analysis reveals that the SAR signature for a given braking target is effectively a composite of three curved smear portions. One portion is a part of a parabola that is obtained from the constant-velocity target motion at the initial SAR collection time. Next, the second portion is that of a part of a different parabola that is generated from the final constant target velocity segment during the SAR collection interval. The third curved portion of the full moving target signature forms a connection between the parts of the two parabolas that are due to the initial and final constant velocity segments of the full target motion during the SAR measurement interval.