Ground Moving Target Signal Analysis in Complex Image Domain for Multichannel SAR

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.

Section: B Constant Turning Radius Targetssupporting

confidence: 75%

“…Fig. 5 presents the corresponding image formation smear, with an overlay of the predicted contour obtained via (21) and (22). Clearly, this result does not have the traditional parabolic or hyperbolic shape but instead has the appearance of two separate smears of opposite concavity which are connected at one end.…”

Section: B Constant Turning Radius Targetsmentioning

confidence: 98%

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

IEEE Trans. Geosci. Remote Sensing

2015

“…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.

“…For example, some researchers have attempted to improve the detection of such targets via the use of focusing methods. [5][6][7][8][9][10][11][12][13][14][15][16][17] A number of other investigators considered various methods for detecting moving targets through these signature techniques. [23][24][25][26][27][28] Finally, these moving target smear have been shown to exhibit curvature in the radar down-range direction.…”

Section: Introductionmentioning

confidence: 99%

Implications of SAR ambiguities in estimating the motion of slow targets

2017

SPIE Proceedings

This paper examines the implications pertaining to the problem of attempting to invert synthetic aperture radar (SAR) measurement data to yield unique estimates of the underlying motion of slow targets in the imaged scene. A recent analysis has demonstrated that ambiguities exist in estimating the kinematics parameters of surface targets for general bistatic SAR collection data. In particular, a procedure has been developed which generates alternate target trajectories which give the same SAR measurements as that of the true target motion. The current paper extends the earlier analysis by generating specific numeric examples of alternate target trajectories corresponding to the motion of a given slowly moving target. This slow-target case reveals the counter-intuitive result that a single SAR collection data set can be generated by target trajectories with significantly different, and possibly opposing, heading directions. For example, the true motion of a given target can be moving towards the mean radar position during the SAR collection interval, whereas a valid alternate trajectory can correspond to a target that is moving away from the radar. The present analysis demonstrates the extent of the challenges associated with attempting to estimate of the underlying motion of targets using SAR measurement data.