Automated performance evaluation of skew-tolerant clocking schemes

In this paper the authors evaluate the timing and power performance of three skew-tolerant clocking schemes. These schemes are the well known master–slave clocking scheme (MS) and two schemes developed by the authors: Parallel alternating latches clocking scheme (PALACS) and four-phase parallel alternating latches clocking scheme (four-phase PALACS). In order to evaluate the timing performance, the authors introduce algorithms to obtain the clock waveforms required by a synchronous sequential circuit. Separated algorithms were developed for every clocking scheme. From these waveforms it is possible to get parameters such as the non-overlapping time and the clock period. They have been implemented in a tool and have been used to compare the timing performance of the clocking schemes applied to a simple circuit. To analyse the power consumption the authors have electrically simulated a simple circuit for several operation frequencies. The most remarkable conclusion is that it is possible to save about 50% of the power consumption of the clock distribution network by using PALACS.     

一种非均匀Weibull杂波背景中的CFAR检测器

针对传统恒虚警(CFAR)算法在非均匀环境下,待检测单元(CUT)与参考窗的分辨单元不具有独立同分布(IID)特性,检测器性能出现剧烈下降的问题,提出一种新的CFAR检测器。该检测器首先引入一种M-N杂波边缘二元积累实现非均匀杂波边缘提取;然后,对数据平面内相邻杂波边缘内的数据,利用一种地形特征分类算法实现对地形的分类编号;最后,根据地形编号选择与CUT相同地形的分辨单元作为参考单元实现CFAR检测,则所选择的参考单元与CUT具有IID特性。利用实测数据验证M-N杂波边缘二元积累检测算法和地形特征分类算法的有效性。计算机仿真证明:文中提出的CFAR检测器的性能,比传统CFAR检测器的性能有明显提升。     

CFAR detection for multistatic radar

In this paper a multistatic radar system with n transmitters and one receiver is considered and several constant false alarm rate (CFAR) algorithms for detection are introduced. The decision statistics of the proposed detectors are the sum of the n largest returning signals in an array of N+n range cells. It is shown that the proposed decision statistic satisfies the CFAR condition and it is justified that the sum of the largest returning signals is the optimal statistic. The proposed CFAR detectors are simulated both in homogenous and non-homogenous backgrounds and their performances are compared with the performance of a monostatic radar of higher power. It is shown that a multistatic radar outperforms a monostatic radar under equal transmit power condition.     

Performance analysis of the modified versions of CFAR detectors in multiple-target and nonuniform clutter

A constant false alarm rate (CFAR) in the presence of variable levels of noise is usually a requirement placed on any modern radar. The CA- and OS-CFAR detectors are the most widely used ones in the CFAR world. The cell-averaging (CA) is the optimum CFAR detector in terms of detection probability in homogeneous background when the reference cells have identical, independent and exponentially distributed signals. The ordered-statistic (OS) is an alternative to the CA processor, which trades a small loss in detection performance, relative to the CA scheme, in ideal conditions for much less performance degradation in nonideal background environments. To benefice the merits of these well-known schemes, two modified versions (MX- and MN-CFAR) have been recently suggested. This paper is devoted to the detection performance evaluation of these modified versions as well as a novel one (ML-CFAR). Exact formulas for their false alarm and detection performances are derived, in the absence as well as in the presence of spurious targets. The results of these performances obtained for Rayleigh clutter and Rayleigh target indicate that the MN-CFAR scheme performs nearly as good as OS detector in the presence of outlying targets and all the developed versions perform much better than that processor when the background environment is homogeneous. When compared to CA-CFAR, the modified schemes perform better in ideal conditions, and behave much better in the presence of interfering targets.     

Object CFAR detection in gamma-distributed textured-backgroundimages

The authors introduce a new non-Gaussian CFAR detector, specifically a CFAR detector for gamma-distributed textured backgrounds. The design and analysis of the detector is carried out in several steps: basic design, analysis in only noise conditions, bias removal and analysis in the presence of correlation. The authors also discuss the possibility of applying a data prewhitening technique to control the false alarm rate in correlated textured patterns. In terms of detection, they analyse the performance of their detector for a certain model of target. They compare its performance to that of the ideal detector, and quantify in which conditions the former behaves closely enough to the latter     

A performance review of out-of-frame detection schemes for DS1signals

A basic framework is given for performance comparisons of several frame detection schemes used to identify individual channels within a DS1 digital transmission system in either the superframe (SF) or extended superframe (ESF) format. Key criteria include mean misframe times, out-of-frame detection times, reframe times, tolerance to error bursts and application considerations. Through the use of Markov chain models, analytical solutions for the mean misframe and out-of-frame detection times are derived in terms of the bit error ratio and frame period. Performance comparisons of several frame detection schemes in various error conditions are made     

Dynamic reconfiguration schemes for megabit BiCMOS SRAMs and performance evaluation

In this paper two dynamic configuration schemes are discussed for megabit BiCMOS static random access memories (SRAMs). Dynamic reconfiguration schemes allows failure detection at the chip level and automatic reconfiguration to fault free memory cells within the chip. The first scheme is a standby system approach where the I/O lines of the memory can be dynamically switched to spare bit slices in the SRAM. This scheme is implemented through a switching network at the memory interface. Every memory access is controlled by a fault status table (FST) which memorizes the fault conditions of each memory block. This FST is implemented outside the memory system. A second dynamic reconfiguration scheme for BiCMOS SRAMs is addressed through a graceful degradation approach. Basic design considerations and performance evaluation of megabit BiCMOS SRAMs using dynamic reconfiguration schemes are presented. The basic properties of the proposed schemes and a prototype VLSI chip implementation details are discussed. BiCMOS SRAM access time improvement of about 35%, chip area of 25%, and chip yield of 10% are achieved, respectively, as compared to conventional methods. A comparison of reliability improvement of 1 Mb BiCMOS SRAMs using dynamic configuration schemes is presented. These two dynamic reconfiguration schemes have considerable importance in reliability improvement when compared to conventional methods. The major advantage is that the size of reconfiguration of the system can be considerably reduced.     

On the implementation and performance of single and doubledifferential detection schemes

A variety of schemes for performing differential detection in environments characterized by frequency offset are discussed. All of the schemes involve encoding the input phase information as a second-order difference and performing an analogous second-order differential detection at the receiver. Because of the back-to-back differential detection operations at the receiver, The performance of most of the schemes is considerably degraded relative to that of first-order differential detection schemes. However, the latter are quite sensitive to frequency offset and, in many instances, cannot be used at all. It is demonstrated that via a simple enhancement of using a 2 T s (instead of T s) delay in the second stage of the encoder and first stage of the decoder, the performance degradation can be significantly reduced. This result is significant in view of the fact that it comes without any penalty in implementation complexity     

一种新的分块恒虚警率检测技术

经典的参量型恒虚警率检测器只在特定的背景环境下才能得到较高的检测性能,而低空监视雷达的工作环境较为复杂,需要一种对杂波环境具有较强稳定性的检测器。为此,对传统的检测技术进行了改进,提出了一种新的分块恒虚警率检测技术。该技术通过对参考单元进行适当分块来提高对不同环境的适应能力,弥补了传统恒虚警率检测技术需要杂波背景分布的不足,增强了检测算法的通用性。给出了该算法在均匀杂波环境和杂波边缘环境下的虚警概率理论公式。计算机仿真验证了该技术的可行性和有效性。     

Distributed cell-averaging CFAR detection in dependent sensors

Constant false alarm rate detection is considered in a decentralized, two-sensor context. Cases with observations which are dependent from sensor to sensor are investigated, for which results have been lacking. The in-phase and quadrature components of the received narrowband observation at each sensor consist of a common weak random signal in additive Gaussian combined clutter and noise. The sensors use cell-averaging CFAR tests to each generate binary decisions which are sent to a fusion center. Optimal sensor thresholds are found and the performance of the best schemes using AND and OR fusion rules are compared. The ability of these schemes to maintain constant false alarm probability in the presence of clutter edges is also studied     

Analog seizure detection and performance evaluation

Epilepsy is the most prevalent neurological disorder affecting both adults and children. Over two-and-one-half million individuals in the United States have epilepsy and 25% of them do not respond to drugs. A significant focus of current research efforts is the development of a fully implantable device for real-time seizure detection and automated warning and blockage of seizures. The purpose of this paper is to describe and demonstrate the feasibility of incorporating a novel tool, the percentile tracking filter into a successful, validated seizure detection algorithm to create an analog seizure detection device. We demonstrate, in a small-scale study, that the performance of this analog implementation is statistically similar to a digital implementation of a previously described and successfully validated seizure digital algorithm. This analog implementation can be realized into an application specific integrated circuit that is suitable for a fully implantable device for seizure monitoring, warning and treatment, which is likely to consume very little power, a feature of practical value.     

极不均匀合成孔径雷达杂波建模及恒虚警检测

基于合成孔径雷达(SAR)城区极不均匀杂波实际数据和Cramer-Von Mises距离,本文运用Rayleigh分布、Weibull分布、K分布和G分布对杂波进行了分布拟合检验.结果表明Rayleigh分布和Weibull分布难以拟合极不均匀场景回波,K分布只能部分拟合,而G分布的拟合程度最好.进而,针对G分布下的目标恒虚警检测问题,本文给出了不同参考单元条件下达到给定检测性能时信噪比随形状参数的变化曲线,分析了恒虚警(CFAR)性能损失随分布参数变化的原因,得到了确定恒虚警门限的有效方法.     

连续波频率调制雷达频域恒虚警检测的研究

光纤光耦合技术及数字处理技术的进步使得基于光纤连续波频率调制(FMCW)雷达技术快速发展。针对激光雷达时域信号处理在远程目标探测中的不足,根据雷达传统时域中的多重门限以及FMCW雷达回波频谱的特点,使用了频域恒虚警率(Constant False Alarm Rate,CFAR)目标检测技术。该CFAR技术是基于对回波信号进行时频变换,并对其结果进行解析,得出目标的距离及速度信息,实现在恒定虚警概率的前提下最大化提高系统的探测率。     

New formulation of GNSS acquisition with CFAR detection

This paper deals with the analysis of the acquisition process performed by a global navigation satellite system (GNSS) receiver with a pilot and data channel or in case of GNSS hybrid receiver. Signal acquisition decides the presence or absence of GNSS signal by comparing signal under test with a fixed threshold and provides a code delay and a Doppler frequency estimation, but in low signal conditions or in a noisy environment; acquisition systems are vulnerable and can give a high false alarm and low detection probability. Firstly, we introduce a cell‐averaging‐constant false alarm rate (CFAR) then a data‐pilot cell‐averaging‐CFAR detector fusion based to deal with these situations. In this context, we use a new mathematical derivation to develop a closed‐form analytic expressions for the probabilities of detection and false alarm. The performances of the proposed detector are evaluated and compared with a non‐CFAR case through an analytical and numerical results validated by Mont Carlo simulations. Copyright © 2016 John Wiley & Sons, Ltd.     

A survey and performance evaluation of decentralized aggregation schemes for autonomic management

Over the last few years, autonomic network and service management has emerged as a serious alternative to traditional management approaches. In these systems, distributed entities, called autonomic managers, perform monitoring and control operations in an autonomous and decentralized way. The monitoring consists of providing indicators on the state of the system. Several monitoring solutions have been proposed to enable autonomic managers to obtain a partial or complete knowledge of an indicator through aggregation processes. Such a profusion of solutions raises important questions regarding the choice of an aggregation scheme in a particular operational context and for a particular management information because each class of solution presents different benefits and weaknesses. That is why, in this paper, we present the result of our study of decentralized aggregation schemes for autonomic network and service monitoring. The contribution is twofold: (i) a survey of decentralized aggregation schemes based on a refined taxonomy; and (ii) the results of an evaluation campaign we performed to compare typical aggregation schemes. These results highlight the context, in terms of the managed network behaviour as well as information dynamics, in which each aggregation scheme outperforms the others, thus helping autonomic management system designers in choosing the best scheme for their management purpose. Copyright © 2014 John Wiley & Sons, Ltd     

Watermarking schemes evaluation

In this article we have used a duality approach to the watermarking evaluation problem by splitting the evaluation criteria into two (independent) groups: functionality and assurance. The first group represents a set of requirements that can be verified using agreed series of tests; the second is a set of levels to which each functionality is evaluated. These levels go from zero or low to very high. We are investigating how evaluation profiles can be defined for different applications and how importance sampling techniques could be used to evaluate the false alarm rate in an automated way     

Quality-guided lane detection by deeply modeling sophisticated traffic context

Lane detection is a useful technique in modern autonomous vehicles systems, which assists vehicle to accurately localize itself according to detected road lines. Traditional methods leveraged edge detection and Hough transform based algorithms to plot lines along the detected lane. Noticeably, they did not take the informative feature road gradient into account. In addition, most previous deep learning-based algorithms consider lane detection as pixel-wise lane segmentation, where only fixed number of lanes can be detected. In order to solve these limitations, we propose a quality guided lane detection algorithm by modeling the sophisticated traffic context, where variable number of lanes can be satisfactorily handled. Specifically, we first leverage chessboard images for camera calibration to calculate correspondence between real world and image coordinate system. Subsequently, we capture image regions of interest that only contains lane information by leveraging the prior knowledge and image quality scores. Afterwards, we design an end-to-end two-stage CNN architecture for lane detection, where binary lane mask is utilized for lane matching. Comprehensive experiments have demonstrated that our proposed method can cope with variable number of lanes effectively.     

DISTRIBUTED CFAR SIGNAL DETECTION BASED ON AREA FUSION

The multisensor detection area partitioning is considered. An approach is presented to the fusion in each detection area where the sensor uses different thresholds and then at system level. The expressions of the detection probability and false alarm probability are given. An application of the method is illustrated to distributed CFAR detection systems. The result shows that the system detection probability may be improved by setting different thresholds for a detector.     

基于ARMA模型的CFAR网络入侵检测方法研究

提出了一种基于ARMA网络流量模型的CFAR入侵检测系统。采用ARMA模型对网络流量进行预测,并运用雷达信号处理中的恒误警CFAR技术,选取检测阀值以判定是否存在入侵信号。利用林肯实验室DARPA数据对系统进行试验,结果表明,此方法与AR预测模型相比,具有更高的检测率和更低的误警率。     

基于ADSP-TS201的雷达恒虚警实现

介绍了ADI公司的新一代高性能TigerSHARC处理器ADSP—TS201的性能。给出了基于ADSP—TS201的瑞利分布杂波背景中雷达目标恒虚警检测原理及软、硬件实现方法,并给出了仿真实验结果。利用ADSP—TS201的强大功能实现雷达高速信号处理。