编码超声血流多深度检测

血流信息检测及其成像因其独特的优势,在临床上得到广泛应用。但常规经颅多普勒超声系统仍采用模拟和数字电路结合的传统技术,这类系统容易受到外界干扰且不能进行多深度检测。文章设计出一种全数字多普勒超声血流检测系统方案,弥补了传统模拟系统存在的问题。多普勒仿体和人体实验结果表明,该系统能够进行多深度检测,确定血管的深度;同时,还提高了检测灵敏度、超声穿透力和系统成像分辨率。     

编码超声血流多深度检测

血流信息检测及其成像因其独特的优势,在临床上得到广泛应用。但常规经颅多普勒超声系统仍采用模拟和数字电路结合的传统技术,这类系统容易受到外界干扰且不能进行多深度检测。文章设计出一种全数字多普勒超声血流检测系统方案,弥补了传统模拟系统存在的问题。多普勒仿体和人体实验结果表明,该系统能够进行多深度检测,确定血管的深度;同时,还提高了检测灵敏度、超声穿透力和系统成像分辨率。     

Design concepts of instruments for vector parameter identification

The concepts for design of phase-sensitive measuring instruments, based on two-phase synchronous detection, are proposed. The main idea of the design is to utilize the advantages of both analog and digital signal processing methods via combining the principles of synchronous detection and averaging with the principles of integrating analog-to-digital and functional digital-to-analog conversion     

Operator errors when operating with digital readout devices and measures for eliminating them

Conclusions Until now digital measuring instruments have rarely matched the result devices with the psychological properties of an operator. Such a situation has been caused by a number of reasons, and particularly the conviction that subjective errors are not characteristic of digital devices and also by the lack of suitable recommendations.Comparative analysis of the information characteristics of digital and analog readouts, conducted in this work, allow us to recommend the following measures for increasing the effectiveness of the perception of the indications of digital indicators: use of information redundancy for the creation of a spatial visual form, corresponding to the equivalent analog readout by addition of one or several dimensionalities; elimination of the noninformational content (noise) from the readout with the aid of an indication register; separating out the dynamics of change of indications.Translated from Izmeritel'naya Tekhnika, No. 11, pp. 71–73, November, 1971.     

Development and Application of a Programmable Partial Discharge Calibrator

A programmable partial discharge (PD) calibrator composed of an arbitrary waveform generator that is series connected to a capacitor is described. The voltage waveform supplied by the generator is software controlled. The characteristics and capabilities of the calibrator are presented, and the procedures used for its characterization are discussed. The calibrator can reproduce different types of pulses, which include both the corona and PDs of random amplitudes and the predetermined phase relationship with respect to the high-voltage (HV) supply. Examples of the actual discharges measured in the laboratory are compared with the corresponding pulse sequences generated by the calibrator. Finally, by means of this developed instrument, the performances of four partial-discharge-measuring systems equipped with analog and digital measuring instruments are investigated and compared by generating suitable pulse charge sequences.      

Classification of digital measuring instruments

Summary A classification schematic of digital instruments (Fig. 2) based on the above article includes the classification of digitizers by their method of comparing the unknown and known quantities, by the method used in measuring by their equipment and their output devices, that is, their method of presenting the results.The examination of the design principles of digital instruments only with respect to these classifications shows a considerable variety of measuring methods for which these instruments can be used. It should be noted, however, that the above classification does not include many derived types of digital circuits. However, digital instruments based on intermediate types may be of great importance. Thus, for instance, the simultaneous utilization of digitizers and analogue instruments, which is characteristic for differential methods of measuring the difference between a discrete and an unknown analogue quantity, is employed in a considerable number of instruments [5,7]. In the category of intermediate types of digital instruments should also be included partly automatic instruments which comprise contact and contactless elements, digitizers based on the simultaneous utilization of different methods of comparing the unknown and known quantities, etc.The proposed classification of digital instruments is undoubtedly not the only possible one. However, in our opinion, it covers the basic principles for designing digital instruments and indicates certain possible tendencies in their development.In conclusion the author considers it his duty to express his gratitude to Corresponding Member of the Academy of Sciences, USSR K. B. Karandeev and to Prof. M. I. Levin for their valuable advice, as well as to candidate of technical sciences B. S. Sinitsyn and engineers B. V. Karpyuka and A. N. Kasperovich for the useful observations made by them in discussing the material dealt with in this article.     

An integration of memory-based analog signal generation intocurrent DFT architectures

One method for the testing of mixed analog/digital integrated circuits involves the digital encoding of analog signals into an aperiodic pulse-density modulated (PDM) serial bit stream and using it to stimulate a device under test (DUT). This paper describes a method for obtaining a short periodic approximation of the PDM pattern and identifies two methods of integrating this analog test scheme into the current digital test environment: RAM- and scan-based storage. Using such design-for-test logic as the 1149.1-1990 JTAG architecture and a typical RAMBIST controller, these analog signal generation techniques can be added to digital integrated circuits (IC's) with minimal additional hardware overhead     

Accurate self-synchronizing technique for measuring transmitterphase and frequency errors in TDMA digitally encoded cellular systems

Measurement of phase and frequency errors, affecting the transmitted signal in digitally encoded cellular systems, is discussed here. To this aim, a new, cost-effective technique, particularly suitable in time domain multiple access (TDMA) systems, is proposed. In contrast to other measurement methods or instruments, the proposed technique gains burst synchronization on the analyzed signal through digital signal-processing, thus avoiding the need of sophisticated and expensive analog triggering solutions. Only a general-purpose data acquisition system is, in fact, required to capture a proper time window of the transmitted signal, preliminarily down-converted to intermediate frequency. Furthermore, in the same way as other methods or instruments, phase and frequency errors are evaluated according to a standard digital signal-processing procedure, which applies both for the actual and reference phase trajectory of the transmitted signal. The technique makes both trajectories available just at the end of the aforementioned burst synchronization stage, thus also optimizing the computational burden     

高精度温度控制方式述评

对高精度温度控制系统中常用的模拟控制方式、数字控制方式和模拟/数字控制方式作了比较,目的在于找到既能满足计量检定恒温装置所需的技术指标、又方便实用的控制方式.     

随钻测量中工具面角的模拟解算

针对井眼轨迹的测量问题,根据测量仪器的输出信号与钻具姿态信息存在一定的三角函数关系,提出了一种工具面角模拟解算方法.分析了工具面角数字计算方法及其误差,基于模拟函数发生器构造了一种新颖的反正切函数求解电路,可以直接获取工具面角.对不同井斜角和工具面角的情况下进行了试验测试,数据分析表明,该方法可行,并具有较高的精度,可用于快速的姿态参数解算.     

A Technique for Synthesizing Digital Filters

In designing digital systems, one often faces the task of replacing a given analog filter by an equivalent digital filter. This paper proposes a method for synthesizing such digital filters in the time domain. It is assumed that the pulsed transfer function of the digital filter is a ratio of two rational polynomials. The coefficients are then determined by least-square fitting the digital filter to the analog filter's sampled input and output data. The resulting equations for computing the coefficients are linear. It is shown that the digital filter is essentially related to the analog filter, the sampling time, and the power spectrum of the signal being processed. If the signal is band-limited and the sampling frequency is sufficiently high, the digital filter can then be simply approximated by the Z transform of the analog filter multiplied by the sampling period.     

Architecture and design of an open ATE to incubate the development of third-party instruments

To test next-generation system-on-a-chip (SoC) ICs, an open architecture automatic test equipment (ATE) has been conceived. Open architecture provides a framework to integrate software and instruments of different vendors into the ATE. The specifications of this framework, known as OPENSTAR specifications, have been developed by the Semiconductor Test Consortium (STC). The deployment of third-party instruments and modules in this framework is plug-and-play to achieve the optimal test configuration for a given SoC. In this test system, each modular unit can be replaced with another modular unit from a different vendor, and the tester can be reconfigured to map the test resources according to the requirements of device-under-test (DUT). The only restriction in using the third party modules is that each modular unit must adhere to the standard interfaces of the integrating framework and should conform to the OPENSTAR specifications. Hardware modules can be any functional unit such as a digital pincard, an analog card, device power supply (DPS), instruments such as waveform generator, etc. Similarly, software modules can be a tool or utility such as a test executive tool, system monitoring or licensing tools, unit-level controllers, database, microsoft office utilities, application specific software for controlling equipment, etc. The basic structure of this test system, module structure, calibration/diagnostics and synchronization as well as system reconfigurability is described in this paper.     

Classification of analog electrical measuring instruments

Conclusions From the large number of criteria that take into account the physical and technical nature of analog electrical measuring instruments, three have been singled out in the proposed classification which define the purpose, the metrological features (method of realizing the measuring process), and the technological features (nature of the major subassemblies). All analog instruments can be classified in accord with these criteria regardless of their structure, complexity of the equipment, and operating principles of the measuring transducer.Translated from Izmeritel'naya Tekhnika, No. 11, pp. 53–54, November, 1971.     

Measuring mixed-signal substrate coupling

A measurement method is proposed to characterize the substrate coupling between digital and analog sections of a mixed-signal CMOS chip. Induced noise and spurious signals can be measured by a custom-designed analog sensor. This paper proposes a method that, when given such a sensor, allows to measure the crosstalk between digital and analog chip sections. Calibrated sampling scope measurements illustrate the performance of the measurement setup     

Hardware-Software Tradeoffs for Analog Automatic Test Instruments

This paper will show that in general the cost and reliability of ATE analog instruments are improved if hardwired logic is minimized and software is given the task of step-by-step control of these instruments. Test speed is perhaps the most important parameter that may be adversely affected by this tradeoff. However, by careful design of the ATE software system, test speed for software-controlled instruments can be improved substantially.     

Research on Digital and Analog Electronic Experiment Teaching Course Management based on UltraLab Network Experiment Platform

Digital circuit and analog circuit courses are basic courses for students of science and engineering universities. Among them,the practical courses are of great significance for students to master the knowledge of electronics. In order to make teachers teaching more efficiently and students studying more quickly,how to update the experimental course in teaching reform is the key point. This paper analyzing the present situation of teaching in the digital circuit and analog circuit courses,the teaching questions in universities. On the basis of it,the innovation measures of experimental teaching methods and contents are discussed. Our school tries to introduce the UltraLab network experiment platform,reform and optimize the teaching methods of related courses.And it' s accelerating the construction and development of emerging engineering education' s process,reducing effectively the teacher's time for managing in equipment,improving the students' ability to use instruments.     

High Precision SAR ADC Using CNTFET for Internet of Things

A high precision 10-bit successive approximation register analog to digital converter (ADC) designed and implemented in 32nm CNTFET process technology at the supply of 0.6V, with 73.24 dB SNDR at a sampling rate of 640 MS/s with the average power consumption of 120.2 μW for the Internet of things node. The key components in CNTFET SAR ADCs are binary scaled charge redistribution digital to analog converter using MOS capacitors, CNTFET based dynamic latch comparator and simple SAR digital code error correction logic. These techniques are used to increase the sampling rate and precision while ensuring the linearity, power consumption and noise level are within the limit. The proposed architecture has high scalability to CNTFET technology and also has higher energy efficiency. We compared the results of CNTFET based SAR ADC with other known architectures and confirm that this proposed SAR ADC can provide higher precision, power efficiency to the Internet of things node.     

Certain instances of the use of electronic pulse counters in measurement techniques

Summary Conversion circuits can be used for designing monitoring and measuring equipment for mpst diverse applications. Such instruments, side by side with digital devices, are intended to measure directly various physical quantities, and provide, in conjunction with units used in computer equipment, the possibility not only of producing complex measuring equipment, but also of processing data obtained in measuring several parameters and providing results which are of direct interest to the operator.In order to raise the reliability and efficiency of such instruments and to decrease their over-all dimensions and weight, it is advisable in the near future to transistorize these sets.     

虚拟仪器在导弹测试发控系统中的应用

设计的基于PC/104嵌入式计算机系统的虚拟仪器,具有测量各种电学信号和时频信号功能;同时具有输出各种模拟信号、不同频率和幅值的脉冲信号及各种波形信号的信号源功能.其测量精度高,输出信号精度高,可用于导弹测试发控系统对其进行各种测试和控制.     

滚动轴承振动加速度信号积分测试技术研究

滚动轴承出厂时需要根据国家标准进行振动检测。对滚动轴承的振动进行测量的方法主要是采用速度型测振和加速度型测振。由于速度型测振仪和加速度型测振仪所采用的传感器不同,两者的测量结果有相关性,但测量结果并不一致。传统的轴承测振仪采用模拟电路,对加速度信号进行准确积分,难度较大;随着计算机测量技术的迅速发展,运用数字量测试和积分技术,可以采用对加速度信号进行积分得到速度的方法进行测试。通过对轴承的加速度信号进行积分,进行振动速度测量,可以在同样的测试条件下对轴承的振动加速度和振动速度进行比较,具有实际应用价值。本文采用数字量测试技术,以深沟球轴承为研究对象,对加速度积分算法进行研究,利用MATLAB和Lab VIEW软件编写了数字滤波器和时域积分算法,减去了时域积分产生的趋势项,降低了趋势项误差。通过实际测量实验,所得结果与轴承行业所用的标准精密模拟积分器所得结果具有较好的一致性,可以满足轴承振动速度测量的需要。