Scan BIST with biased scan test signals

The conventional test-per-scan built-in self-test （BIST） scheme needs a number of shift cycles followed by one capture cycle. Fault effects received by the scan flipflops are shifted out while shifting in the next test vector like scan testing. Unlike deterministic testing, it is unnecessary to apply a complete test vector to the scan chains. A new scan-based BIST scheme is proposed by properly controlling the test signals of the scan chains. Different biased random values are assigned to the test signals of scan flip-flops in separate scan chains. Capture cycles can be inserted at any clock cycle if necessary. A new testability estimation procedure according to the proposed testing scheme is presented. A greedy procedure is proposed to select a weight for each scan chain. Experimental results show that the proposed method can improve test effectiveness of scan-based BIST greatly, and most circuits can obtain complete fault coverage or very close to complete fault coverage.

WAVELET ANALYSIS IN TESTING SIGNALS

In this paper, Wavelet Analysis Method (WAM) is introduced to analyse the non-stationary, shock signals. The theory and construction method of wavelet, the fast algorithms of wavelet analysis are presented. As an example, the gear testing signal has been analysed by WAM, and the results of WAM are compared with that of Fourier spectrum. The advantages of WAM are clearly shown.

Feasibility of differentiating defect signals of ultrasonic testing for laser weld based on independent component analysis theory

Separating noise from observed signals was studied.When the small defect in the T-shape laser welding joint was inspected by ultrasonic testing system adopting independent component analysis(ICA) theory to process the signals.The principle of automatic ultrasonic testing signals processing and negentropy law of ICA were introduced.The experimental data were processed using relative analysis tools and results showed that the ICA could separate defects signals from noise effectively in laboratory.

Adaptive Signal Conditioning Technology in Fighter Weapon System Test

In order to realize the real-time and precise test for a weapon system of a certain type of fighter,a signal classification method according to attributes is proposed,common input channels for multiple signals are configured optimally,and a test adapter and an adaptive signal conditioning module is designed. The hardware of conditioning module can be configured flexibly and the programmable test range can be adjusted owing to programmable multiplexer. An FPGA adaptive filter is designed by the calculated filter coefficient vectors with LMS method to solve the problem of parallel test of fighter weapon system in electromagnetic interference environment. The adaptive signal conditioning technology is characterized by high efficiency,precision and integration. Its application makes the test system successful to conduct real-time and parallel test for a weapon system,which is developed based on VXI bus and virtual-instrument technology.

Wigner-Matrix-Based Normality Test and Application to Weak Signal Detection in SISO/SIMO Systems

Based on the asymptotic spectral distribution of Wigner matrices, a new normality test method is proposed via reforming the white noise sequence. In this work, the asymptotic cumulative distribution function （CDF） of eigenvalues of the Wigner matrix is deduced. A numerical Kullback-Leibler divergence of the empiric-d spectral CDF based on test samples from the deduced asymptotic CDF is established, which is treated as the test statistic. For validating the superiority of our proposed normality test, we apply the method to weak SIPSK signal detection in the single-input single-output （SISO） system and the single-input multiple-output （SIMO） system. By comparing with other common normality tests and the existing signal detection methods, simulation results show that the proposed method is superior and robust.

Analyzing and Seeking Minimum Test Instruction Set of Digital Signal Processor for Motor Control

The relativity of instructions of motor control digital signal processor (MCDSP) in the design is analyzed. A method for obtaining a minimum instruction set in plac e of the complete instruction set during generation of testing procedures is giv en in terms of the processor presentation matrix between micro-operators and in structions of MCDSP.

Analogue and Mixed-Signal Production Test Speed-Up by Means of Fault List Compression

Accurate test effectiveness estimation for analogue and mixed-signal Systems on a Chip (SoCs) is currently prohibitive in the design environment. One of the factors that sky rockets fault simulation costs is the number of structural faults which need to be simulated at circuit-level. The purpose of this paper is to propose a novel fault list compression technique by defining a stratified fault list, build with a set of “representative” faults, one per stratum. Criteria to partition the fault list in strata, and to identify representative faults are presented and discussed. A fault representativeness metric is proposed, based on an error probability. The proposed methodology allows different tradeoffs between fault list compression and fault representation accuracy. These tradeoffs may be optimized for each test preparation phase. The fault representativeness vs. fault list compression tradeoff is evaluated with an industrial case study—a DC-DC (switched buck converter). Although the methodology is presented in this paper using a very simple fault model, it may be easily extended to be used with more elaborate fault models. The proposed technique is a significant contribution to make mixed-signal fault simulation cost-effective as part of the production test preparation.

A Recursive Method of Time-Frequency Analysis for the Signal Processing of Flutter Test with Progression Variable Speed

Focused on the non-statlonarity and real-time analysis of signal in flutter test with progression variable speed （FTPVS）, a new method of recursive time-frequency analysis is presented. The time-varying system is tracked on-line by building a time-varying parameter model, and then the relevant parameter spectrum can be obtained. The feasibility and advantages of the method are examined by digital simulation. The results of FTPVS at low-speed wind-tunnel promise the engineering application perspective of the method.

基于IVI-Signal标准的自动测试系统驱动研究

建立通用测试软件平台,实现测试程序集和仪器资源的无关性设计是通用ATS的发展方向;驱动程序作为连接测试程序集和仪器资源的桥梁,在“无关性设计”中起着决定性作用;在分析自动测试系统基本理论和基于IVI-Signal标准的ATS软件平台体系基础上,运用组件技术划分信号角色、定义信号接口,根据仪器资源信号能力提出资源配置文件设计方法并给出XML语言实例,提供了基于测试资源信号能力的驱动设计方案,验证了IVI-Signal标准的可行性,为进一步工程实现提供了依据。

逻辑分析仪SignalTap Ⅱ在系统级调试中的应用

嵌入式逻辑分析仪SignalTapⅡ是QuartusⅡ软件中第二代系统级调试工具,它可以用来捕捉目标芯片内部信号节点处的信息,而又不影响原硬件系统的正常工作。通过一个多波形信号发生器的设计实例,详细阐述SignalTapⅡ的工作流程和参数设置方法。实验结果表明,该测试方法操作方便,实时性较高,能够加快系统的开发流程。

Ultrasonic signal classification based on ambiguity plane feature

Ambiguity function （AF） is proposed to represent ultrasonic signal to resolve the preprocessing problem of different center frequencies and different arriving times among ultrasonic signals for feature extraction, as well as offer time-frequency features for signal classification. Moreover, Karhunen-Loeve （K-L） transform is considered to extract signal features from ambiguity plane, and then the features are presented to probabilistic neural network （PNN） for signal classification. Experimental results show that ambiguity function eliminates the difference of center frequency and arriving time existing in ultrasonic signals, and ambiguity plane features extracted by K-L transform describe the signal of different classes effectively in a reduced dimensional space. Classification result suggests that the ambiguity plane features obtain better performance than the features extracted by wavelet transform （WT）.

Investigation of ionospheric TEC changes related to the 2008 Wenchuan earthquake based on statistic analysis and signal detection

Ionospheric TEC （total electron content） time series are derived from GPS measurements at 13 stations around the epicenter of the 2008 Wenchuan earthquake. Defining anomaly bounds for a sliding window by quartile and 2-standard deviation of TEC values, this paper analyzed the characteristics of ionospheric changes before and after the destructive event. The Neyman-Pearson signal detection method is employed to compute the probabilities of TEC abnormalities. Result shows that one week before the Wenchuan earthquake, ionospheric TEC over the epicenter and its vicinities displays obvious abnormal disturbances, most of which are positive anomalies. The largest TEC abnormal changes appeared on May 9, three days prior to the seismic event. Signal detection shows that the largest possibility ofTEC abnormity on May 9 is 50.74%, indicating that ionospheric abnormities three days before the main shock are likely related to the preparation process of the Ms8.0 Wenchuan earthquake.

Metal magnetic memory testing for early damage assessment in ferromagnetic materials

In order to investigate the physical mechanism of metal magnetic memory testing, both the influences of earth magnetic field and applied stress on magnetic domain structure were discussed. Static tension and fatigue tests for low carbon steel plate specimens were carried out on hydraulic servo testing machine of MTS810 type and magnetic signals were measured during the processes by the type of EMS-2003 instrument. The results indicate that the initial magnetic signals of specimens are different before loading. The magnetic signals curves are transformed from initial random to regular pattern due to the effect of two types of loads. However, the shape and distribution of magnetic signal curves in the elastic region are different from that of plastic region in tension test. While in fatigue test those magnetic signals curves corresponding to different cycles are similar. The H_p(y) value of magnetic signals on the fracture zone increases dramatically at the breaking transient time and positive-negative magnetic poles occur on the two parts of fracture zone.

Design and application of wireless signal strength measurement system on the near-ground

The wireless communication system's performance is greatly constrained by the wireless channel characteristics,especially in some specific environment.Therefore,signal transmission will be greatly impacted even if not in a complicated topography.Testing results show that it is hardly to characterize the radio propagation properties for the antenna installed on the ground.In order to ensure a successful communication,the radio frequency(RF)wireless signal intensity monitor system was designed.We can get the wireless link transmission loss through measuring signal strength from received node.The test shows that the near-ground wireless signal propagation characteristics still can be characterized by the log distance propagation loss model.These results will conduce to studying the transmission characteristic of Near-Earth wireless signals and will predict the coverage of the earth's surface wireless sensor network.

Research on A Checking Method of Vibration Characteristics for Test System

To ensure the accuracy and precision of vibration test,a universal checking method is proposed.The use of the method is discussed and an actual example is given.First,the calibration of the 7703A-500 type sensor is analyzed on the basis of frequency response method.The frequency range of normal working can be determined by the exact calibration of sensitivity,frequency response and linearity.For the basic problem of abnormal signals appearing in test system,the method of zero check and loading vibration source are developed.The frequency spectrum of output signals is employed to distinguish the noise signal,unknown source signal and useful signal effectively.Finally,the experimental results reveal the importance to improve the accuracy of the results of practical vibration test.

A Point-of-Care Test System for Biochemical Blood Analysis Based on ADUC824

A point-of-care test system has been studied in this paper.It was used to determine substances in blood such as Hemoglobin (HB),Aspartate Aminotransferase (AST),Creatine Kinase (CK) and so on.Based on the principle of amperometric determination,the research on detecting weak current signals was carried on.At the same time as to the weak signals (nA level),magnifying,sampling and processing the signals were also studied.Controlled by ADUC824 and assisted by other units, every substance could be determined automatically and rapidly integrated with the corresponding biosensor.In the experiment, the minimum detectable current of the instrument (YT2005-1) is 0.2 nA.With regard to the 1 nA which the experiment demanded,it could be up to the mustard.And the system can provide results in 180 s with a long term stability.

复杂电能信号谐波时频域特征分析及其对电能计量影响

为准确分析复杂电能信号谐波时频域特性对电能计量的影响,提出了一种零值搜索-短时傅里叶变换时频域电压、电流信号幅度和相位分析算法,利用信号波形过零特征,自适应调整短窗傅里叶变换的时域窗宽,解决了电网频率波动导致的相位累积效应对相位分析的影响,算法的幅值分析误差为10-3、相位分析误差小于1°;建立了复杂电能信号时频域数据表征模型和4类时频域全局化特征矩阵提取算法,解决了时频域特性表征与提取的问题;以典型非线性动态负荷中频炉为分析案例,分析给出了其4类时频域全局化特征,并建立了畸变波形动态电能测试信号特征模型,通过辅助实验验证了4个时频域全局化特征对电能表动态超差的影响,提出了对国际和国内标准修改的建议。

Simulation of large-scale numerical substructure in real-time dynamic hybrid testing

A solution scheme is proposed in this paper for an existing RTDHT system to simulate large-scale finite element （FE） numerical substructures. The analysis of the FE numerical substructure is split into response analysis and signal generation tasks, and executed in two different target computers in real-time. One target computer implements the response analysis task, wherein a large time-step is used to solve the FE substructure, and another target computer implements the signal generation task, wherein an interpolation program is used to generate control signals in a small time-step to meet the input demand of the controller. By using this strategy, the scale of the FE numerical substructure simulation may be increased significantly. The proposed scheme is initially verified by two FE numerical substructure models with 98 and 1240 degrees of freedom （DOFs）. Thereafter, RTDHTs of a single frame-foundation structure are implemented where the foundation, considered as the numerical substructure, is simulated by the FE model with 1240 DOFs. Good agreements between the results of the RTDHT and those from the FE analysis in ABAQUS are obtained.

Experimental validation of a signal-based approach for structural earthquake damage detection using fractal dimension of time frequency feature

This article extends a signal-based approach formerly proposed by the authors, which utilizes the fractal dimension of time frequency feature （FDTFF） of displacements, for earthquake damage detection of moment resist frame （MRF）, and validates the approach with shaking table tests. The time frequency feature （TFF） of the relative displacement at measured story is defined as the real part of the coefficients of the analytical wavelet transform. The fractal dimension （FD） is to quantify the TFF within the fundamental frequency band using box counting method. It is verified that the FDTFFs at all stories of the linear MRF are identical with the help of static condensation method and modal superposition principle, while the FDTFFs at the stories with localized nonlinearities due to damage will be different from those at the stories without nonlinearities using the reverse-path methodology. By comparing the FDTFFs of displacements at measured stories in a structure, the damage-induced nonlinearity of the structure under strong ground motion can be detected and localized. Finally shaking table experiments on a 1：8 scale sixteen-story three-bay steel MRF with added frictional dampers, which generate local nonlinearities, are conducted to validate the approach.

基于磁场模型的矿用钢丝绳检测信号特性试验研究

电磁检测是矿用钢丝绳缺陷可靠的检测手段之一。基于电磁法的矿用钢丝绳缺陷检测,目前存在缺陷与信号特性表征规律不明确的问题,定量识别时存在无关信号特性,影响识别准确性。采用三维磁偶极子理论计算、Maxwell模拟仿真与试验相互验证的方法,总结漏磁信号特性与缺陷变化之间的表征关系。首先建立磁场环境下的钢丝绳三维磁偶极子理论模型,应用模型对标准缺陷处进行磁场理论计算并进行Maxwell模拟仿真;分别提取理论值与仿真值的峰/谷绝对值、波宽、峰谷差值、峰谷值宽度四项信号特性,进行缺陷与信号的表征分析;最后设计缺陷进行试验验证,得到试验数值的斯皮尔曼相关系数。试验结果表明:缺陷的宽度、深度与峰/谷绝对值、波宽、峰谷差值3个信号特征值呈正相关,与峰谷值宽度无明显相关性;缺陷长度与峰/谷绝对值呈先上升后下降的趋势,与波宽、峰谷差值、峰谷值宽度呈正相关。并且发现宽度缺陷信号幅值最强,长度缺陷信号幅值最弱,深度信号幅值居中,峰谷差值和峰谷绝对值与缺陷相关性最高。该研究具有一定的工程指导价值。