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A multi-port power amplifier (MPA) is a multi-input multi-output system that is capable of amplifying multiple input signals simultaneously by a set of shared power amplifiers without mutual interference. In a practical MPA, the component imperfections reduce the port isolation, which introduces leakage or cross-port interference. A patent-pending type-based calibration technique is studied in this...
Most significant part of radar target detection problems can be solved by using the method of statistical detection theory. Here the objective of the proposed optimal detection algorithm is to give a maximum detection probability for fixed false alarm probability. It is assumed that target is stationary and energy reflected from the target is distributed. The proposed detection algorithm has a squared...
Extremely low frequency (ELF) atmospheric noise is non-Gaussian, consisting of the sum of a Gaussian background and narrow pulses caused by lighting strokes. Therefore, the conventional detection method for signal in Gaussian noise gets worse. In this paper, a new structure for signal detection in the ELF atmospheric noise is proposed. First, the ELF atmospheric noise is modeled as a symmetric α-stable...
This paper deals with the adaptive detection of a signal of interest in the presence of Gaussian noise with unknown covariance matrix (CM). To this end, we resort to a Bayesian approach based on a suitable model for the probability density function (PDF) of unknown CM. Under this assumption, the maximum a-posteriori (MAP) estimation of CM is derived. The MAP estimate is in turn used to yield Bayesian...
This paper proposes a robust detector for detection of known signals in impulsive noise environments. The distribution of the noise is assumed to be a mixture of Laplacian distribution giving a sharp peak around the true value of the signal of interest and uniform distribution modeling the contributions of completely unknown noise. This type of noise appears in problems related to estimated pitch...
Hypothesis tests are used to compare and show the efficiency of drugs. However, usual tests do not perform properly whenever the number of variables is greater than, or of the same order of magnitude as, the number of observations. In this paper, we propose an alternative to usual multiclass multivariate group comparison tests such as MANOVA or Wilcoxon tests. We present a pattern recognition approach...
In this paper, a new blind carrier frequency and phase offset detector, and modulation order identifier are presented for phase shift keying (PSK) signals. These operations are intermediate steps between signal detection and demodulation, and play a key role in various military and non- military applications. As compared with previous related approaches, the proposed algorithm provides a fully blind...
In this work motivated by a hierarchical spatially adaptive image prior that we have developed for additive watermarking; we first, propose a new perceptual mask which improves robustness of additive watermark detectors in the spatial domain. The proposed mask is based on the local image variations along the two principal directions and enhances the watermark's energy while satisfying the imperceptibility...
This paper presents a discrete wavelet transform (DWT) domain watermark detection approach using Gaussian mixture model (GMM) with automated model selection. More specifically, instead of using traditional expectation maximization (EM) algorithm for parameter estimation in mixture model, where the number of model components need to be fixed in advance, the proposed approach employs the component-wise...
The problem of the detection of a signal in the presence of broad-band noise and interferences that lie in a subspace that is imperfectly known is considered. It is assumed that a basis (or generating set) of the interference subspace is known up to additive white Gaussian noise. This amounts to assuming that each of these basis vectors lies in a cone, the aperture of which depends upon the level...
Scanning probes can be used for storage of data at ultra-high areal densities, beyond those achieved by other techniques. Thermo-mechanical probe storage is one variant of scanning-probe technology in which data is stored in the form of indentations in thin polymer films. A simplified channel model of thermo-mechanical probe storage is first introduced, derived from a comprehensive characterization...
A number of action recognition methods make use of spatio-temporal features. These features often consist of local spatio-temporal descriptors centered at locations provided by an interest point detector. The extracted descriptors will then serve as input to classification algorithms. The correct scale of these descriptors is an essential parameter to be determined. Improved information quality has...
Interest points have been used as local features with success in many computer vision applications such as image/video retrieval and object recognition. However, a major issue when using this approach is a large number of interest points detected from each image and created a dense feature space. This influences the processing speed in any runtime application. Selecting the most important features...
A modified Sobel edge detection is proposed in this paper. Dempster-Shafer theory, also known as the theory of belief function, is applied to improve the drawbacks of the conventional Sobel operator, for instance, the thick edge and sensitive to noise. The reason is that by selecting the mass function, Dempster-Shafer theory can distinguish the edge pixels from the uncertain edge pixels correctly,...
Non-coherent detection using multiple pulses is very useful in radar detection, especially in the case that the phase information of return pulses is unavailable. This paper addresses the performance of non-coherent CFAR detection based on goodness-of-fit (GoF) tests compared with non-coherent CFAR integrator (NCCI) in different clutter environments by simulation experiments, when the assumed and...
In this paper, the statistic characteristics of the digital channelized receiver are studied in the context of additive white Gaussian noise. Based on the statistic characteristics, the automatic censored mean level (ACML) detector is proposed and its performance is analyzed by simulation. The results show that the simulated performance curves are very similar to the theoretical curves for the detection...
Edge detection is an important field in image processing. It can be used in many applications such as feature detection and extraction. An edge is detected as the discontinuity in intensity level of a point. So edges are mostly detected using either the first derivatives, called gradient, or the second derivatives, called Laplacien. In this paper, we propose a new edge detector using the gradient...
This paper presents a novel methodology to perform matching between image points described by their respective features. Traditionally, such correspondences are determined by computing the similarity between descriptor vectors associated to each point which are obtained by invariant descriptors. Our methodology first obtains a coarse global registration among images, which constrains the correspondence...
Radar fast threshold constant false alarm rate (CFAR) detector, which keeps CFAR by estimating background and adjusting adaptive threshold, is widely used for detecting targets in synthetic aperture radar images. Two typical CFAR detectors based on sliding windows, the cell-averaged CFAR (CA-CFAR) detector and the order-statistics CFAR (OS-CFAR) detector are compared in this paper firstly. The results...
In this study, the effects of adding independent noise to observations of a suboptimal detector are studied for M-ary hypothesis-testing problems according to the minimax criterion. It is shown that the optimal additional noise can be represented by a randomization of at most M signal values under certain conditions. In addition, a convex relaxation approach is proposed to obtain an accurate approximation...
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