一种新的准随机LDPC卷积码及窗译码

以Gallager随机LDPC分组码为基础,通过列置换、置数、剪切与合并,构造了一种新的（l,3,6）准随机LDPC卷积码.针对该码类,提出了一种窗扇尺寸固定、滑动步长可选的窗译码算法,大幅降低了寄存器开销和译码延时.仿真实验界定了滑动步长的取值范围,验证了构造方案和窗译码的有效性,测试了不同约束度的准随机LDPC卷积码的误码性能,结果显示约束度l仅为1535即可获得距离香农限约1dB的纠错能力.     

A Quasi-Random Approach to Space–Time Codes

This paper presents a quasi-random approach to space–time (ST) codes. The basic principle is to transmit randomly interleaved versions of forward error correction (FEC)-coded sequences simultaneously from all antennas in a multilayer structure. This is conceptually simple, yet still very effective. It is also flexible regarding the transmission rate, antenna numbers, and channel conditions (e.g., with intersymbol interference). It provides a unified solution to various applications where the traditional ST codes may encounter difficulties. We outline turbo-type iterative joint detection and equalization algorithms with complexity (per FEC-coded bit) growing linearly with the transmit antenna number and independently of the layer number. We develop a signal-to-noise-ratio (SNR) evolution technique and a bounding technique to assess the performance of the proposed code in fixed and quasi-static fading channels, respectively. These performance assessment techniques are very simple and reasonably accurate. Using these techniques as a searching tool, efficient power allocation strategies are examined, which can greatly enhance the system performance. Simulation results show that the proposed code can achieve near-capacity performance with both low and high rates at low decoding complexity.      

准随机跳频信号的二维处理

高频雷达工作的波段十分拥挤,因而可用的连续带宽比较窄,雷达获得距离分辨力极为有限.为避开干扰频段能够提高系统带宽,本文采用了一种频带不连续的准随机跳频信号.并根据信号的特点,系统地提出了该信号的二维信号处理方案.仿真表明,这种方案具有解距离-速度模糊的能力,能有效地抑制最大距离旁瓣,较好地实现了距离速度二维分辨.     

IDDT Testing versus IDDQ Testing

IDDQ testing has progressed to become a worldwide accepted test method to detect CMOS IC defects. However, it is noticed that observing the average transient current can lead to improvements in real defect coverage, which is referred to IDDT testing. This letter presents a formal procedure to identify IDDT testable faults, and to generate input vector pairs to detect the faults based on Boolean process. It is interesting to note that those faults may not be detected by IDDQ or other test methods, which shows the significance of IDDT testing.     

AD转换器在数字测试仪上测试实现的探讨

近年来,出现越来越多的数模混合器件,或内部包含有模拟电路诸如ＡＤ转换器,ＤＡ转换器或滤波器的μＣＰＵ或ＡＳＩＣ数字器件。在纯数字测试系统上实现ＡＤ转换器的测试,对测试上述的包含一部分模拟电路的数字器件有十分重要的意义。本文以Ｔ３３４７Ａ为例,介绍在纯数字测试系统上实现ＡＤ转换器的测试。     

Achieving SCA Conformance Testing with Model-Based Testing

Time-to-market and implementation cost are high-priority considerations in the automation of digital hardware design. Nowadays, digital signal processing applications are implemented into fixed-point architectures due to its advantage of manipulating data with lower word-length. Thus, floating-point to fixed point conversion is mandatory. This conversion is translated into optimizing the integer word length and fractional word length. Optimizing the integer word-length can significantly reduce the cost when the application is tolerant to a low probability of overflow. In this paper, a new selective simulation technique to accelerate overflow effect analysis is introduced. A new integer word-length optimization algorithm that exploits this selective simulation technique is proposed to reduce both implementation cost and optimization time. The efficiency of our proposals is illustrated through experiments, where selective simulation technique allows accelerating the execution time of up to 1200 and 1000 when applied on Global Positioning System and on Fast Fourier Transform part (FFT) of Orthogonal Frequency Division Multiplexing chain respectively. Moreover, applying the optimization algorithm on the FFT part leads to a cost reduction between 17 to 22 % with respect to interval arithmetic and an acceleration factor of up to 617 with respect to classical max-1 algorithm.     

电磁兼容检测实验室测试系统相符性比对研究

电磁兼容测试结果与检测实验室可靠性程度直接相关,检测实验室自身质量是保证电磁兼容测试结果准确性先决条件,检测实验室测试系统相符性则成为电磁兼容系统性能评估中需要考虑的关键内容和重要指标。因此,检测实验室测试系统相符性比对是实现电磁兼容系统评估研究的基础工作之一。本文首先针对电磁兼容检测实验室测试系统相符性比对的特点,结合自己几年来的测试实践论述了电磁兼容检测实验室测试系统相符性对比方案,然后提出了具体的案例同时进行了详细的分析,最后总结出了影响电磁兼容检测实验室测试系统相符性因素,整个案例和分析过程及结果可作为电磁兼容检测实验室测试系统相符性比对的手段和依据,具有重要的现实指导意义。     

符合性测试和互操作性测试的相关性(第2版)

传统上讲，符合性测试主要用于电信产业，而互操作性测试主要用于国际互联网络。这两种测试方法存在各自的优点和缺点，结合使用两种方法，能够使测试过程的效果达到最大化；同时还介绍了欧洲电信标准研究院（ETSI）的标准化活动。     

Testing microprocessors

The testability of microprocessors has become a very important question, especially for device manufacturers. Defining a set of worst case input vectors to exhaustively test still presents one of the major testing problems. This paper discusses a test strategy for microprocessors where the internal logic is separated into two types: data logic and control logic. This approach can be used to ease the definition of the test vectors A practical example is presented in the form of a test program for the SAB 8080 A microprocessor. The worst case functional pattern that was created lasts only 130 ms when run at 2.5 MHz.     

测量的要求

与法规第76部分所有的性能要求一样,上述规定适用于: (1)所有的有线电视系统(所服务的用户少于1000户的系统可与当地主管部门协商采用较宽的标准。然而,倘若没有这种书面协议,小系统也必须遵守与大系统同样的性能要求): (2)所有的频道; (3)所有的用户引出线; (4)所有的时间。     

滤波器的测试

像传输线那样,可以测试任何一种滤波器或陷波器的阻抗和频率响应。滤波器在其带宽内应该具有等于输入激励源阻抗和负载阻抗的输入阻抗和输出阻抗。为了测试阻抗,可以进行开路测试和短路测试。为了更加了解这种测试,请考虑图2.43滤波器或传输线的电路图。该电路图为平衡     

检测实验室的合作与检测结果的相互认可

一、引言 由第三方权威机构对产品质量作出科学评价并颁发证书这种认证制度始于二十世纪初,并在近二、三十年被世界上几乎所有国家采用。这种评价制度因为由第三方技术权威机构按严格的程序科学地对产品质量和性能作出评价结论、因而具有很高的可信任性。认证制度得以广泛采用的另一个因素、是认证活动为政府部门在推动法规实施时提供了经济、有效的帮助,从而赢得了政府对认证的信赖。例如美国的能源之星（ｅｎｅｒｇｙｓｔａｒ）认证制度就是世界上发展最成功的白愿性认证制度之一,由于它时节能和环保有显著的效果和深远的意义,美国政…     

软件测试中接口测试概述与实践

本文探讨了软件测试中接口测试,针对客户需求提出了应对策略和方法,研究了接口测试必须要遵循的几点原则和要求,旨在为接口测试提供相关的参考.     

Testing Result Statistics-Based Rapid Testing Method for Safety-Critical System

Safety-critical system （SCS） has highly demand for dependability, which requires plenty of resource to ensure that the system under test （SUT） satisfies the dependability requirement. In this paper, a new SCS rapid testing method is proposed to improve SCS adaptive dependability testing. The result of each test execution is saved in calculation memory unit and evaluated as an algorithm model. Then the least quantity of scenario test case for next test execution will be calculated according to the promised SUT＇s confidence level. The feedback data are generated to weight controller as the guideline for the further testing. Finally, a compre- hensive experiment study demonstrates that this adaptive testing method can really work in practice. This rapid testing method, testing result statistics-based adaptive control, makes the SCS dependability testing much more effective.     

嵌入式软件覆盖测试的研究和应用

基于软件覆盖率测试的基本理论,针对嵌入式软件测试的特点和难点,介绍了如何利用测试工具LDRA testbed获取嵌入式软件的结构覆盖率,给出了测试环境建立、源代码插装等具体实践过程,并进一步总结了嵌入式软件覆盖测试的经验和方法。     

黑盒测试技术在雷达软件系统测试中的应用

随着现代雷达技术的发展,雷达软件系统测试技术的研究和应用对于雷达软件质量的提高具有重要意义。文中以某雷达的软件系统测试为例,阐述了如何灵活采用等价类划分、边界值分析等多种黑盒测试技术来设计切实可行的测试用例,使得这些测试用例不仅能达到较大的雷达软件功能需求的测试覆盖率,而且可以有效地发现雷达系统软件设计中的缺陷。实践证明,应用这些黑盒测试技术在该雷达软件系统测试的用例设计中极大地提高了测试效率,取得了较好的效果,具有一定的工程应用价值。     

单元测试中访问权限受限的成员函数的测试

本文详细介绍了在面向对象语言的单元测试中，访问权限受限的成员函数测试的必要性，并进一步讨论了在Java语言中利用反射机制突破访问权限的限制，完成受限函数测试的具体实现方法。解决了在正常情况下无法对访问权限受限的成员函数进行有效测试的问题，大大提高了开发速度和软件质量。     

降低复杂PCB测试的成本及测试方案的规划

随着元件数和焊点数的不断增多,新型封装以及片式元件的使用,PCB测试比以往面临着更多的挑战。测试方案的选择与电路板的复杂程度有极大的关系。比较分析了3种复杂程度PCB测试的成本,并介绍了几种用于复杂PCB的测试方案。