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In radar signal reconnaissance digital receiver based on DFT (Discrete Fourier Transform), automatic CFAR (Constant False Alarm Rate) detection in frequency domain is necessary in processing of peak-seek algorithm. A CMLD-CFAR (Censored Mean Level Detector CFAR) algorithm in frequency domain is presented. By researching the threshold generating algorithm of pulse radar signalspsila spectrum under...
In we developed a Viterbi algorithm for efficient detection of M-ary phase-shift keyed (MPSK) sequences received over the additive, white, Gaussian noise (AWGN) channel with an unknown carrier phase. Its performance approaches that of coherent detection, but the observation interval for forming the decision metric is fixed and chosen based on prior statistical knowledge of the carrier phase characteristics...
In this paper, non-dimensional parameter immune detectors are constructed using some non-dimensional parameter which are more hypersensitive to single fault combined with negative selection mechanism of artificial immune system. Regarding complex fault as a type new occurring fault and is gone into fault space to train, fault character can be extracted, and fault can be diagnosed. The machine unit...
Fully exploiting the phase and magnitude information in received data is crucial to the detection of cognitive radio signals, and this is usually done in the time domain. In fact, the same set of information can also be exploited in the frequency domain in the form of power spectrum. The most appealing one is the multitaper spectrum (MTS) estimator, which enjoys a high estimation accuracy and relatively...
The radio fuze will be out of order easily because of small size and high integration. In order to improve the testability, an effective method to achieve rapid detection and fault isolation is to determine reasonable test-sets and a best diagnosis strategy. Based on the functional block diagram, a fault message matrix among every module of inner radio fuze is built and some optimum test-sets are...
Two new theorems show how deliberately adding quantizer noise can improve statistical signal detection in array-based nonlinear correlation detection even in the case of infinite-variance alpha-stable channel noise. The first theorem gives a necessary and sufficient condition for such quantizer noise to increase the detection probability for a fixed false-alarm probability. The second theorem shows...
Collusion attack is a cost-effective attack against digital fingerprint. To develop an efficient collusion-resistant fingerprint scheme, it is very important for the detector to study the behavior of the colluders and the performance of collusion attack. Although several prior works have been proposed in the literature to analyze the performance of collusion attack, few effort has been made to explicitly...
Spectrum sensing is important for cognitive radios to utilize the idle spectrum opportunities, and recently cooperation schemes have been introduced to enhance spectrum sensing in specific areas. However, when a mobile cognitive node roams among heterogenous wireless network, it will be difficult to catch the changes of primary user's behavior, or to setup the cooperation relationship with local network...
Alpha stable distribution has gained much attention due to its generality to represent heavy-tailed and impulsive interference. In such non-Gaussian interference, the detection key is to evaluate the zero-memory nonlinearity (ZMNL) function of locally optimal (LO) detector. Unfortunately, there is no closed form expression for the probability density function (PDF) of alpha-stable distributions. Hereby,...
Reducing the number of secondary data used to estimate the Clutter Covariance Matrix (CCM) for Space Time Adaptive Processing (STAP) techniques is still an active research topic. Low rank CCM estimates have already been proposed but only for homogeneous and Gaussian clutter. We propose in this paper to extend the low-rank CCM methods for heterogeneous and/or non-Gaussian clutter. We derive a new detector...
An iterative detection aided down-link (DL) space division multiple access (SDMA) system is proposed. The base station (BS) requires DL channel state information (CSI) estimated by and fed back from the mobile station (MS) for separating the DL signals to be transmitted to the MSs from the BS. We investigate the achievable system performance subject to finite-accuracy CSI feedback. The achievable...
Despite the current Internets critical importance, portions of its architecture are still vulnerable to attacks ranging from malicious software exploits to denial-of-service (DoS). Most of these attacks and vulnerabilities experienced on the Internet today are due to the fact that the Internet architecture and its supporting protocols was primarily designed for a benign and trustworthy environment,...
Doubletalk detector (DTD) is essential to keep adaptive filter from diverging in the presence of near-end speech in acoustic echo cancellation (AEC), and there was a receiver operating characteristic (ROC) to characterize DTD performance. However, the traditional ROC for evaluating DTD used a static time-invariant room acoustic impulse response and could not evaluate DTDs which distinguish echo path...
In this work, a detector scheme for the detection of signal in a group of non-Gaussian narrowband interferences and white Gaussian noise is developed. Since there exists no closed-form probability distribution for this type of disturbance modeling, the key innovation lies in the use of characteristic function rather than the probability distribution to both design and implement the detector. Parameter...
In a parallel distributed detection in order to design the optimal fusion rule, the fusion center needs to have perfect knowledge of the performance of the local detectors as well as the prior probabilities of the hypotheses. Such knowledge is not available in most practical cases. In this paper, we propose a blind technique for the M-ary distributed detection problem. We derive the probability mass...
A fully affine invariant image comparison method, Affine-SIFT (ASIFT) is introduced. While SIFT is fully invariant with respect to only four parameters namely zoom, rotation and translation, the new method treats the two left over parameters : the angles defining the camera axis orientation. Against any prognosis, simulating all views depending on these two parameters is feasible. The method permits...
The diversification and intelligent of hackerspsila attacks makes it hard for single intrusion detection measure to attain favorable detection result. Therefore, it becomes one of the new hot spots in current research that how to combine multiple security measures to provide the network system more effective protection. A new computer information security protection system based on data fusion theory...
For cognitive radio technology, energy detection using the fast Fourier transform (FFT) is a common technique for spectrum sensing so that underutilized frequency bands can be opportunistically used while causing no detrimental interference to the primary user. However, traditional detection and false alarm rate analyses of FFT-based detectors require incorporating the characteristics of the propagation...
A FFT-based partial matched filter (PMF) acquisition threshold setting method for fast GPS acquisition is presented. Normal distribution and numerical fitting technique instead of real decision variable (DV) distribution are used in derivation to approximate the threshold expression, and the modification method for the threshold expression is also presented. The threshold expression is based on the...
Standard edge detectors such as Canny edge detector use a local gradient operator to find the ridges in digital images. In this study we show that peer groups and simple variance calculations can be used to improve the performance of gradient operators. Some of the pixels near the threshold are weaker edge pixels of the objects in the image and others are unimportant edges created by unevenness of...
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