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Modulation in the mean value of power (sigma0) from diffuse radar backscattering necessitates a compound model for high-resolution clutter statistics. Non-stationary internal structures in the scene under observation result in strong fluctuations in sigma0, and are identified as textures in the backscattering. Texture detection in clutter leads to interpretation of the surface structures present in...
Synthetic aperture radar (SAR) is a kind of coherent imaging system that produces a random pattern, named speckle, which degrades the quality of SAR images and affects their further application seriously. Therefore how to restore SAR image from speckled one has become a necessary step in post-processing of image. In this paper, a new despeckling algorithm is presented based on wavelet transform using...
Periodogram is a simple and efficient way to detect and estimate parameters of sinusoidal signals which is widely used in radar where we need to detect moving targets. In this paper, the detection performance of the periodogram and its variants such as Bartlett, Welch methods, and a proposed Bartlett-based method is evaluated. Performance evaluation through the receiver operating characteristics (ROCs)...
This paper presents the statistical distribution functions of the radar cross section of a group of ground man-made targets in some specific operationally viable cases. It demonstrates the variety of distribution functions that can arise, the multimodal nature of them, the frequency variability and more importantly underlines the significance of the operational scenario including velocity information...
In this paper we consider the problem of the estimation of the digital elevation model (DEM) of a ground scene starting from dual baseline interferometric synthetic aperture radar (SAR) signals. classical maximum likelihood (ML) estimation techniques require the knowledge of the joint probability density function (PDF) of the two measured interferometric phases. Usually the joint PDF expression is...
Passive radars are not at all new to the radar community though they lately raised interest among researchers for some specific features that make them more appealing than classic active radar systems. In fact, having the TX and RX located at two different positions, and the adoption of signals carrying other kinds of information such as GSM (either classical or the 1800/1900 MHz version) or FM modulated...
The paper proposes a novel constant false alarm rate (CFAR) detector using Markov chain models, an innovative new technique that will utilize the finer resolution of RADARSAT-2 to yield improved detection performance for higher-resolution objects. The Markov chain based CFAR detector extends traditional PDF based CFAR detection to first-order Markov chain model by considering both correlation between...
For composite hypothesis testing, the generalized likelihood ratio test (GLRT) and the Bayesian approach are two widely used methods. This paper investigates the two methods for signal detection of a known waveform and unknown amplitude with distributed sensors. It is first proved that the performance of the GLRT can be poor. Secondly, a direct way of improving the GLRT is proposed. Thirdly, an approximate...
In this paper we study the statistical distributions of bistatic scattering from Pierson-Moskowitz sea surfaces. The Monte Carlo simulation method is applied and the Maxwellpsilas equations are solved numerically using the Banded Matrix Iterative Approach. By assuming normal-distributed and correlated real and imaginary scattering components, we derive analytical probability density functions (pdfs)...
This paper presents an improved estimation scheme when the clutter distribution is unknown. The Empirical Likelihood (EL) is a recent semi-parametric estimation method which allows to estimate unknown parameters by using information contained in the observed data such as constraints on the parameter of interest as well as an a priori structure. The aim of this paper is twofold. First, the empirical...
This paper addresses adaptive high resolution radar detection of range-distributed target embedded in compound-Gaussian clutter modeled as a spherically invariant random process (SIRP). Echoes backscattered from range-distributed target are modeled as a subspace random signal by using multiple dominant scattering models. At the design stage we resort to the so-called two-step GLRT-based design procedure...
In this contribution, a low-complexity particle filter (PF) is proposed to track the parameters of the signal reflected by a target illuminated with a digital-video-broadcast terrestrial (DVB-T) signal. The tracked parameters are the delay (time of arrival), the azimuth and elevation of arrival, the Doppler frequency, the complex amplitude of the target signal, as well as the rates of change of all...
The sensitivity of track before detect processing to the choice of clutter model in the measurement correction stage was examined through processing of real and simulated data containing radar echo returns of a small maritime target in sea clutter. The potential for achieving significant detection performance improvements by utilizing K and KA distributed clutter models in place of the simpler Rayleigh...
Heterogeneous clutter environments are frequently encountered in radar processing and constitute a main source of performance degradation for most adaptive detection schemes which use the sample covariance matrix (SCM). This degradation is mainly due to the fact the SCM is no longer a consistent estimate of the clutter covariance matrix in the cell under test (CUT). In a recent paper we proposed a...
Recent and future space missions for Earth Observation grant a growing avaibility of high resolution SAR images. The analysis of this data tipology critically requires exploiting the spatial-contextual information in the related images. In this paper we propose a contextual measure of the amount of information in a SAR image based on Gauss Markov Random Fields, which takes into account both the radiometric...
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