数字音频／视频仪器大展宏图

最近一、两年来,DVD(数字视频光盘)间世,数字电视播送等业务正在积极筹办之中,这股者频/视频产品的数字化热潮,不仅带动了相关设备与元器件的研制开发工作,对于测量仪器厂家,也产生了重大影响。数字化音频/视频产品,对测试的要求全然不同于传统的模拟式产品,继续沿用和发展传统的模拟式仪器技术,已经毫无意义。其实,市场上对于传统仪器门类中的音频/视频测试仪器的需求量,从1993年开始,已经处于逐年减少的状态之中。用于评估DVD的光盘、播放机、驱动器及拾取头等的基准,远     

液晶显示器音频自动化测试研究

文章介绍了液晶显示器音频工作原理,引出音频测试的必要性。通过阐述音频分析仪的三种控制方式,给工程师编写程序,控制测试仪器工作,最终实现音频测试自动化,提供一定参考。     

PC仪器的发展

PC仪器(PC instruments),也称个人仪器(personal instruments),指的是一类以个人计算机为基础的测试和测量系统(personal-computer-based test and measurement system)。这类仪器系统充分利用个人计算机(PC)的资源,系统中所有仪器的显示和控制全部集中于PC,仪器本身只是基本的测试和测量功能部件,不再具有传统仪器的独立形态,而是以插件或模块(modnle)的形式被插入PC的总线插槽或其扩展机箱中,仪器的成本和尺寸明显缩减。     

几种最常用的测试仪器总线

众所周知,测试是生产过程中不可缺少的步骤,但测试费用越来越高,最好能省则省,使用通用仪器或重新配置的仪器是节省测试费用的办法之一,PC基仪器和模块仪器受到欢迎的主要原因就在于此。现今的测试项目较多,包括数字、模拟和混合信号,需要多种仪器构成测试系统。测试某一品种产品后,测试系     

基于LabVIEW与Matlab混合编程的雷达回波起伏特性模拟

目前对雷达回波起伏特性的模拟一般是基于专用回波模拟器的。然而,某些通用仪器具有将Matlab编写的波形文件下载到仪器中以获得自定义波形输出的特点,因此,利用这些仪器可以模拟回波的起伏特性;LabVIEW在测试与测量、仪器控制等领域获得了广泛的应用,他提供了Matlab Script节点,使之可以与Matlab进行通信。因此利用这两种软件可以更好地控制通用仪器,实现回波起伏特性模拟。     

基于STD标准的仪器可互换技术

仪器可互换技术是新一代自动测试系统的关键技术之一。针对可互换技术只能实现同类仪器的互换,无法实现具有相同信号能力的不同类仪器的互换以及多功能仪器的互换等问题,文中开展面向信号的仪器可互换技术研究。STD标准是信号和测试定义标准,为实现面向信号的仪器可互换技术提供支撑。首先分析面向信号的仪器控制模型,找出测试描述中与仪器相关的重要环节,即信号操作与信号接口的映射关系,以及测试描述与仪器能力的信号匹配;再建立统一的函数接口,实现不同角色信号的标准化映射过程,通过设计自定义匹配流程,根据信号类型及对应的属性表达式实现信号的自动匹配;最后,对仪器互换过程进行验证。结果表明,基于STD标准的仪器可互换技术不仅能够实现同类仪器的互换,还能实现不同类仪器的互换,实现过程简单方便。     

个人机仪器向我们走来

基于个人机的测试仪器将会成为技术人员的测试工具;个人机利用插入扩充槽的模/数转换插卡板,可以构成若干成本低廉的专用测试系统,并有可能替代单机仪器通过GPIB等接口连接而成的测试系统。     

电子测试仪器发展新动向

移动通信、数据传输、光纤通信、网络检测的高速增长促进了电子测试仪器技术的不断改进和发展。专家们指出,在２０００年以后的新世纪里,数字化、模块代、网络化和系统化已成为电子测试仪器发展的新趋势,采用各种各样先进技术的第３代电子测试仪器将不断问世。 通常,电子测试仪器可以分为独立式仪器、模块化仪器和ＰＣ插卡式仪器３个大类。 在实际应用领域中,台式、便携式和手持式独立仪器又分为基础仪器和专业仪器两种。基础仪器通常包括示波器、逻辑分析仪和数字万用表等电子测试仪器;专业仪器则是以网络分析仪、ＲＦ信道仿真器、…     

吉时利在射频测试仪器中新增WiMAX测试功能

美国吉时利（Keithley）仪器公司（NYSE代码：KEI）,日前宣布了一套信号生成与分析工具,扩展了其射频测试功能,实现了对WiMAX信号的测试。吉时利新的测试方案建立在新型硬件平台基础上,降低增加支持新信号标准的难度和成本,例如基于4×4MIMO信道802．16e移动WiMAX Wave2测试,不需要昂贵的硬件升级过程或者其他辅助仪器。     

吉时利在射频测试仪器中 新增WiMAX测试功能

2008年6月23日，美国吉时利仪器公司宣布了一套信号生成与分析工具，扩展了其射频测试功能，实现了对WiMAX信号的测试。该公司最新的测试方案建立在新型硬件平台基础上，降低增加支持新信号标准的难度和成本，例如基于4×4 MIMO信道802．16e移动WiMAX Wave2测试，不需要昂贵的硬件升级过程或其他辅助仪器。此外，这些新型仪器支持低达400MHz低频带测试，这对于正在研发的新一代WiMAX解决方案是一种日益重要的新功能。     

On trends in automatic testing of analog circuits

The rapid change and the turmoil characteristic of the electronics industry today, is evident also in analog testing field. Because an analog electronic circuit or device may be tested many times during its life-time, analog testing has become a significant component of life cycle cost. In this paper, we discuss briefly the emerging trends towards test techniques; testlanguages; test system architectures; test instruments; test computers; and test requirements as related to analog testing field. The topics discussed assume a new importance, however, as VLSI introduces more analog circuits into the digital domain.     

Engineering education for test and measurement designers

Education programs for engineers working in the T&M industry should cover the basics well. An engineer needs an educational foundation that he or she can build on for an entire career. Leading-edge computer technologies (hardware and software) are critical to the development of test instruments. Analog design and digital signal processing of analog signals are also key design skills required by instrument manufacturers     

Switched-capacitor filters: precise, compact, inexpensive

Switched-capacitor filters-silicon ICs that combine features of analog and digital filters-are penetrating markets far beyond the telephone networks for which they were first developed. They are now found in audio equipment, speech analyzers and recognizers, test instruments, and electronic musical instruments. Their precision, compactness, and low cost make them preferable to discrete and hybrid filters, as well as to digital filters. Design engineers needing quantities of inexpensive, precise, self-contained filters make switched-capacitor filters (SCFs) their first choice. The author discusses the construction, operation, building blocks, and problems of SCFs     

石油测井仪器电流检测系统分析

在测井仪器的研发期间,对仪器的功耗要进行监测,利于可以科学的给仪器搭配适合的电池,为此设计了可以在大动态情况下,连续的对直流的小电流进行监测的检测系统,对于系统有连续监测小电流的独特需求,设计出了运用高输入阻抗的方法和差分运放的I/V转换方法选用放大信号、多级硬件的电路滤波和数字的滤波相综合形式的制止干扰的方法,主要是制止系统内的噪声和系统外在的工频干扰;在此之外还运用软件来达到自动量程的效替来实现大范围的电流检测要求,通过实验来实现使用的需求.     

Delta modulation in DVM design

Existing digital voltmeters (DVM) do not sell as well as analog types having parallel capabilities for the simple reason that they cost more. Though the DVM has the superior performance to compete in the popular class of instruments, it must sell for less than 100 dollars. This means new thinking and radical alteration in present designs. New thinking developed the delta modulation DVM discussed here; it has high performance and is economical. Performance figures include an input impedance of >100 M/spl Omega/, an accuracy typically 0.3 percent of full scale, and a noise rejection figure of >60 dB at main frequencies >49 Hz. Power consumption is about 600 mW.     

Testing times for analogue products

The test requirements of the second edition of the European generic immunity standard for residential, commercial and light industry environments (EN50082-1: 1997), differ substantially from those of the first edition (EN50082-1: 1992). In the first edition, the frequency range for radiated immunity testing was 27 MHz to 500 MHz. The second edition extends the frequency range to cover 150 kHz to 80 MHz (for conducted immunity) and 80 MHz to 1000 MHz (for radiated immunity). It also specifies that all RF tests feature amplitude modulation with 1 kHz at a depth of 80% in accordance with EN 61000-4-3 (radiated) and EN 61000-4-6 (conducted). Many product types that formerly complied with the radiated immunity test requirements are failing to comply with the amplitude modulation tests specified in the new edition. As a consequence, wise design engineers will want to re-examine their existing product designs, while reflecting carefully on specific areas on their new product development projects. The author offers guidance and advice for the concerned design engineer     

Test Strategies for Electrode Degradation in Bio-Fluidic Microsystems

Electrode technology is fundamental to numerous actuation and sensing functions in bio-fluidic microsystems that target portable bio-analytical instruments. Within these systems high levels of reliability and robustness are crucial and normally complemented by requirements for extremely low probabilities of false positives or negatives being generated. New methods of validating functionality and integrity of the reading are hence required. Embedded test and condition monitoring are crucial technologies for delivering these capabilities. This paper presents two solutions for detecting degradation in electrodes that interface to fluidic or biological systems. In the first solution, a low frequency, impedance based method for identifying degraded structures within an array is proposed. This method depends on measuring and comparing the impedance of each sensing electrode. This research is backed up by physical measurements from an electrode array for drug testing on cardiac and neuron tissue. In the second solution, a mid-frequency oscillation test technique is proposed that is sensitive to degradation in the bio-fluidic interface capacitance, to contamination and to fouling.     

Direct modulation of semiconductor lasers

Methods for direct modulation of semiconductor lasers are reviewed with the objective of indicating the advantages and limitations of each method. Techniques for producing amplitude, pulse, and frequency modulation of the optical wave are included. The modulation capabilities of present pulsed lasers are analyzed with special attention given to their operation at room temperature. In addition, several ways of producing analog position or width modulation of microwave-rate optical pulses are described, and the capabilities of optical frequency modulation by acoustic waves are reviewed. A new way of obtaining mode-locked optical pulses with a semiconductor laser is also suggested.     

Design of a wide-band frequency synthesizer based on TDC and DVC techniques

A wide-band frequency synthesizer based on time-to-digital (TDC) and digital-to-voltage (DVC) conversion techniques is proposed here. The proposed frequency synthesizer has the capabilities of jitter reduction and large bandwidth, making it more robust for high-frequency applications. A test chip is designed and fabricated in 0.6-/spl mu/m CMOS single-poly triple-metal process. Here, the novel DVC circuit is realized by tristate inverters, where the resolution can achieve 0.2 mV. Control stability of jitter can improve about 24 dB by exploiting the TDC-based controller. In order to achieve high output frequency and large output range, an analog voltage-controlled oscillator is designed to provide a locked range from 900 to 1900 MHz with <22 kHz resolution at 3.3 V. Simulation and test results show that the proposal can work as expected. Moreover, the TDC-based controller can be treated as soft IP to speed up turnaround time.     

手持式电子测量系统的低功耗没计

目前,电池供电的手持式电子测量仪器应用越来越广泛,各种测量仪器都出现了手持式的型号。这给电子设计工程师在系统功耗设计上带来了新的挑战。文中就低功耗系统设计的原则进行了分析,提出了从器件选择,供电效率,系统总体设计等方面来降低功耗的方法。