Loran-C skywave delay detection using ARMA algorithm

The autoregressive moving average technique (ARMA) is applied to the problem of estimating the delay of Loran-C skywaves. The performance of this technique is evaluated and compared with Fourier-based methods. The simulation results show that the ARMA algorithm yields a significantly greater estimation accuracy and that it can also operate successfully with very noisy signals     

Distortion of pulsed signals when the group delay is a nonlinear function of frequency

An analysis for the propagation of a Gaussian-modulated signal through a dispersive channel is presented. Both quadratic-and cubic-type phase distortions are permitted. It is shown that the envelope of the detected signal is characterized by an Airy function.     

Exact computation of group delay and its sensitivities using adjoint-network concept

The exact calculation of the group delay and its derivatives is described for active or passive lumped and/or distributed networks. Two simple examples are included to illustrate the application of the method.     

视频复杂补偿网络群时延理论分析及应用

根据“自控原理”中的梅逊公式及网络理论，对视频矩阵复杂补偿网络进行了理论分析，得出了传递函数和群时延表示式。结果表明，理论分析与实用数据有较好的一致性。     

Bounded delay timing analysis and power estimation using SAT

This paper presents a satisfiability based approach that can be used for accurate estimation of both the critical delay and dynamic transition power consumption of circuits using an event propagation model. The accuracy of the model depends on the accuracy of the gate delays. The speed and efficiency of modern Boolean SAT solvers permits us to model complicated delay models like the Bounded Delay Model, which is better able to capture realistic variations in gate delays due to process variations and changes in operating conditions. We show that timing analysis with bounded delays yields a more accurate critical delay for a circuit than with fixed gate delays. In spite of the high complexity due to unpredictable gate delays, our SAT based approach gives good performance on benchmark circuits, even with a Bounded Delay Model derived from a real industrial library.     

Lowpass delay filters with flat magnitude and group delay constraints

This paper describes the design of finite impulse response (FIR) delay filters that minimize a squared error and have prescribed number of zeros at /spl omega/=/spl pi/ and prescribed magnitude and group delay flatness at /spl omega/=0. An important special case is the design of least squared error lowpass filters with prescribed flatness constraints and zeros at /spl omega/=/spl pi/. Even though the flatness constraints are in general nonlinear functions of the filter coefficients, we show the remarkable fact that for a subclass of the filters a simple orthogonal projection of least squared error filters onto a special linear subspace determined via Baher (1982) filters gives the solution. The paper also introduces the notion of delay filters that are high-order approximations to the ideal delay and establishes their equivalence to Baher filters. This connection gives novel elementary derivations of Baher filters and their properties. Matlab programs are provided at the end of the paper for the design of filters described in this paper.     

基于PGC解调的激光多普勒语音检测系统

提出了一种可实现非接触、远距离、高灵敏度的激光多普勒语音检测系统.该系统采用压电陶瓷(PZT)对迈克尔逊干涉仪的参考信号进行调制,利用相位产生载波法(PGC)对干涉信号解调,提高了零差干涉法的抗干扰性,并且具有光路简单、成本低等优点.推导了干涉信号的解析表达式,数值分析了PGC解调参数的最优值.实验结果表明:该系统能动...     

Computation of group delay and its sensitivities

A method is given for the efficient computation of group delay and its sensitivities for active or passive lumped and/or distributed networks. The method is based on solving a transpose system of equations.     

Message delay analysis for TDMA schemes using contiguous-slotassignments

Under a TDMA (time-division multiple-access) scheme, a station shares a multiple-access communications channel by transmitting its messages during its dedicated time slots. An exact result concerning the queue-sizer and message delay analysis of TDMA systems in which a station is allocated multiple consecutive slots per frame is presented. The generating function of the system queue-size for a general independent arrival message process is obtained. Messages consist of a random number of packets, following a geometric distribution. An exact result for the generating function of the message delay for various common message arrival processes and light bounds for the mean message queue-size and delay are then derived. The results are compared to previously derived approximations. It is also proved that a slot allocation scheme which distributes station slots uniformly over the frame yields a message-delay lower bound. The results also apply to the analysis of time-shared reservation schemes     

BER for optical heterodyne DPSK receivers using delay demodulationand integration detection

Previous work on the bit error rate (BER) performance of differential phase-shift keying (DPSK) including the effects of additive white Gaussian noise (AWGN) and phase noise has concentrated on the delay demodulator with narrow-band intermediate frequency (IF) bandpass filtering (BPF) and sampling detection. No similar analysis has yet been performed for the delay demodulator with wideband IF bandpass filtering and integration detection. Phase noise is an important consideration in coherent optical communication systems and the most widely accepted model is a Brownian motion process. A closed-form BER expression along with detailed Monte Carlo simulation results are presented for the DPSK delay demodulator with wideband IF bandpass filtering and integration detection filtering including phase noise effects using the Brownian motion model. Analytic expressions are also obtained for the moments of the phase noise component of the decision variable. Using these moments, estimates of the phase noise BER floor are produced. It is found that this receiver has noise performance comparable to receivers with narrowband IF bandpass filtering and sampling detectors for signal-to-noise ratio (SNR) and phase noise in the range of practical interest, but with potentially less degradation due to intersymbol interference (ISI)     

对群延迟测量方法的研究

基于对群延迟测量方法优化的目的,采用数字信号处理的方法,设计了计算群延迟的计算机算法。将一部分测量工作转化为计算机的计算工作,从而简化了测量方法,提高了测试效率。以滤波器为例进行测量实验。证明了测量方法和算法的正确性,从而得出了运用数字信号处理的方法并结合计算机快速计算的特点可以优化传统的信号测量方法,提高测量效率的结论。     

群时延的快速测量方法

群时延是射频器件测试中的一项重要待测指标。提出了一种新的群时延测量方法,改善了分辨率和准确性之间的矛盾,同时便于快速实现。本方法所得到的测量结果可用于对射频器件的频率响应特性进行校准,以消除信号通过射频器件时产生的幅度和相位失真,进而减小射频器件对通信和信号处理系统性能所产生的影响。仿真结果验证了提出的测量方法的有效性。     

Computer-aided analysis of solid-state analog delay lines using conventional circuit analysis programs

A method is described for analyzing the two-dimensional behavior of minority carriers in a solid-state analog delay line by applying, without modification, existing computer-aided circuit analysis programs to a lumped model. Development of the model in two dimensions is based on an approximate solution of the minority carrier partial differential equation using an analogous electrical network. The model includes injecting and collecting junction nonlinearities and thereby permits the study of responses to arbitrary external excitations. Several examples of the use of the model are given.     

Wiener filter realization for target detection using group delaystatistics

Several techniques are demonstrated for Wiener filter realization based on group delay statistics. The theoretical analysis shows that an inverse relationship exists between the frequency-domain signal-to-noise ratio and the group delay moving standard deviation and/or group delay moving entropy. Therefore, an adaptive Wiener filter can be realized without a priori knowledge of the signal and noise spectra. Group delay statistics estimation algorithms are proposed and evaluated by simulation. Experimental data from ultrasonic flaw detection are presented to support the effectiveness of the techniques     

Optimization and FROC analysis of rule-based detection schemes using a multiobjective approach

Computerized detection schemes have the potential of increasing diagnostic accuracy in medical imaging by alerting radiologists to lesions that they initially overlooked. These schemes typically employ multiple parameters such as threshold values or filter weights to arrive at a detection decision. In order for the system to have high performance, the values of these parameters need to be set optimally. Conventional optimization techniques are designed to optimize a scalar objective function. The task of optimizing the performance of a computerized detection scheme, however, is clearly a multiobjective problem: we wish to simultaneously improve the sensitivity and false-positive rate of the system. In this work we investigate a multiobjective approach to optimizing computerized rule-based detection schemes. In a multiobjective optimization, multiple objectives are simultaneously optimized, with the objective now being a vector-valued function. The multiobjective optimization problem admits a set of solutions, known as the Pareto-optimal set, which are equivalent in the absence of any information regarding the preferences of the objectives. The performances of the Pareto-optimal solutions can be interpreted as operating points on an optimal free-response receiver operating characteristic (FROC) curve, greater than or equal to the points on any possible FROC curve for a given dataset and detection scheme. It is demonstrated that generating FROC curves in this manner eliminates several known problems with conventional FROC curve generation techniques for rule-based detection schemes. We employ the multiobjective approach to optimize a rule-based scheme for clustered microcalcification detection that has been developed in our laboratory.     

Multipath delay estimation using a superresolution PN-correlationmethod

This paper addresses the problem of high-resolution estimation of a multipath channel delay profile. We propose several improvements to the so-called superresolution pseudo-noise sequence correlation method (SPM) and analyze its performance on time-varying channels. SPM is based on the multiple signal classification (MUSIC) algorithm, which requires decorrelation of the multipath echoes. The proposed improvements enable SPM-based delay estimation in the presence of narrowband interference, and they reduce the necessary transmission window while preserving multipath echo decorrelation. These improvements are analyzed and are applied to underwater acoustic experimental data     

Conditions on the group delay of transmittances

The necessary and sufficient conditions are given for a function to be the group delay of a passive 2-port transmittance. In some important particular cases, more stringent conditions must be imposed. It appears that the realisability of the classical Thomson and Abele families in these cases is purely incidental, and that the last family is actually restricted to low ripples.     

Anomaly detection with a moving camera using multiscale video analysis

Multidimensional Systems and Signal Processing - This paper addresses the problem of abandoned object detection in a cluttered environment using a camera moving along a straight track. The...     

Sensor fusion in anti-personnel mine detection using a two-level belief function model

A two-level approach for modeling and fusion of antipersonnel mine detection sensors in terms of belief functions within the Dempster-Shafer framework is presented. Three promising and complementary sensors are considered: a metal detector, an infrared camera, and a ground-penetrating radar. Since the metal detector, the most often used mine detection sensor, provides measures that have different behaviors depending on the metal content of the observed object, the first level aims at identifying this content and at providing a classification into three classes. Depending on the metal content, the object is further analyzed at the second level toward deciding the final object identity. This process can be applied to any problem where one piece of information induces different reasoning schemes depending on its value. A way to include influence of various factors on sensors in the model is also presented, as well as a possibility that not all sensors refer to the same object. An original decision rule adapted to this type of application is proposed, as well as a way for estimating confidence degrees. More generally, this decision rule can be used in any situation where the different types of errors do not have the same importance. Some examples of obtained results are shown on synthetic data mimicking reality and with increasing complexity. Finally, applications on real data show promising results.     

Performance analysis of 1-persistent ICMA/CD with variable collision detection delay

The throughput of 1-persistent idle-signal-casting multiple access with collision detection (ICMA/CD) with variable collision detection delay is analysed, taking into consideration the effects of multipath signal fading. The packet failure probability with a limited number of reschedulings is also investigated.<>