Moving target indication

About: Moving target indication is a research topic. Over the lifetime, 2653 publications have been published within this topic receiving 32435 citations.

Clutter covariance matrices for GMTI MIMO radar

Abstract: We examine the clutter covariance matrices for ground moving-target indicator (GMTI) multiple-input, multiple-output (MIMO) radar systems, and, in particular, discuss a potential suboptimal increase in their rank This increase in rank will generically degrade the ability of a MIMO GMTI system to detect slowly moving targets We first give a general theoretical analysis and then focus on simulated and experimental data for MIMO systems employing fast-time random, time-division multiple-access (TDMA), and Doppler-division multiple-access (DDMA) waveforms We will show that for the TDMA/DDMA waveforms the clutter covariance matrix in a given Doppler bin is effectively rank 1 for both the simulated and experimental data

Moving target detection for synthetic aperture radar via shadow detection

Abstract: In this paper a novel technique is presented for detecting moving targets in SAR imagery by tracking the shadow of the target over multiple looks instead of using the target direct energy return Unlike the SAR image of a moving target that is blurred and displaced, the shadow of the target is displayed at the true target location The detection performance using shadow is primarily independent of the target radar cross-section and depends upon the clutter to noise signal level A change detection method is developed that provides detection via identification of the target shadow as an outlier from a background distribution The background is inferred from a sequence of SAR images It is shown that simple temporal averaging by alignment of the image for estimating the background works reasonably well with SAR images offering good shadow contrast The technique was successfully demonstrated initially using real radar data from a short range spotlight SAR system Results against weaker shadow signals at longer stand-off range have also proved very encouraging showing a moving target being detected at 10 km standoff range (5 pages)

Tracking Move-Stop-Move Targets with State-Dependent Mode Transition Probabilities

Abstract: This paper presents a method for tracking ground moving targets with a GMTI radar. To avoid detection by the GMTI radar, targets can deliberately stop for some time before moving again. The GMTI radar does not detect a target when the radial velocity (along the line-of-sight from the sensor) falls below a certain minimum detectable velocity (MDV). We develop a new approach by using state-dependent mode transition probabilities to track move-stop-move targets. Since in a real scenario, the maximum deceleration is always limited, a target cannot switch to the stopped-target model from a high speed. Therefore, with the use of the stopped-target model, the Markov chain of the mode switching has jump probabilities that depend on the target's kinematic state. A mode transition matrix with zero jump probabilities to the stopped-target mode is used when the speed is above a certain "stopping" limit (above which the target cannot stop in one sampling interval, designated as "fast stage") and another transition matrix with non-zero jump probabilities to the stopped-target mode is used when the speed is below this limit (designated as "slow stage"). The stage probabilities are calculated using the kinematic state statistics from the interacting multiple model (IMM) estimator and then used to combine the state-dependent mode transition probabilities (SDP) in the two different transition matrices. The experimental results show that the proposed algorithm outperforms previous methods.

Resolution and synthetic aperture characterization of sparse radar arrays

Abstract: The concept of radar satellite constellations, or clusters, for synthetic aperture radar (SAR), moving target indicator (MTI), and other radar modes has been proposed and is currently under research. These constellations form an array that is sparsely populated and irregularly spaced; therefore, traditional matched filtering is inadequate for dealing with the constellation's radiation pattern. To aid in the design, analysis, and signal processing of radar satellite constellations and sparse arrays in general, the characterization of the resolution and ambiguity functions of such systems is investigated. We project the radar's received phase history versus five sensor parameters: time, frequency, and three-dimensional position, into a phase history in terms of two eigensensors that can be interpreted as the dimensions of a two-dimensional synthetic aperture. Then, the synthetic aperture expression is used to derive resolution and the ambiguity function. Simulations are presented to verify the theory.

Multiple target detection using modified high order correlations

Abstract: This work is concerned with the problem of multiple target track detection in heavy clutter. Using the "modified high order correlation" (HOC) process and a track scoring mechanism a new method is developed to perform data association and track identification in the presence of heavy clutter. Using this new scheme any number of very close, crossing or splitting target tracks can be resolved without increasing the computational complexity of the algorithm. The applicability of the method for continuous detection of target tracks that can originate and terminate at any scan is also demonstrated, In addition, the operating characteristics as a function of the clutter density are also provided. Simulation results on all the cases are presented.