矢网在脉冲行波管增益测试中的应用研究

分析了脉冲调制下行波管输出信号频域特性,探讨了矢量网络分析仪在脉冲调制信号测试中的应用,设置矢量网络分析仪接收机带宽可实现宽带检测和窄带检测两种测试方法,结合典型脉冲调制信号分析对比了两种检测方法的脉冲退敏效应,分析了脉冲行波管在不同测试方法下的增益特性,最终确立了宽带检测法作为脉冲行波管增益波动的测试方法,实际测试结果验证了矢量网络分析仪宽带检测法更适合测试脉冲行波管增益波动测试。     

网络分析仪自动检测系统的设计与实现

本文介绍了矢量网络分析仪的测试原理、测试方法和需要检测的参数,根据JJF1495-2014《矢量网络分析仪校准规范》设计系统,重点介绍了系统的硬件设备和软件设计。     

基于85671 A单边带相位噪声自动测试的实现

本文在简要探讨了相位噪声的定义和测试方法的基础上,重点分析了频谱分析仪测试相位噪声的原理及关键技术;研究了HP／Agilent公司的频谱分析仪相位噪声测试选件85671A实现自动测试的难点和解决办法,最后给出了基于85671A实现SSB相位噪声自动测试的具体实现,解决了85671A不能用于自动测试的难题;结果表明这是一种更加高效准确的单边带相位噪声测试方法。     

流动注射分析仪性能测试方法的研究

研究一种简单可靠的流动注射分析仪性能测试方法,阐述了流动注射分析仪测试用标准物质的选择,测试原理及具体的测试方法、步骤和测试结果的处理方法.该测试方法可操作性强,且测试结果具有较好的可比性和溯源性.     

RFID应用服务自动化测试方法

提出一种对RFID应用服务进行测试的自动化方法．使用虚拟终端替代复杂的系统架构中的硬件设备和网络交换过程，并通过设置虚拟脚本，自动与应用服务软件进行数据交换，从而避免安装和调试硬件所带来的困扰，实现在实验室环境下低成本地测试应用服务的能力．这种方法有助于对多层体系和多种硬件并存的系统进行测试，还可以对系统负载的扩展性进行评价．     

用网络分析仪测量电缆的方法

在使用网络分析仪测量电缆损耗的过程中,不正确的测试方法将使被测电缆的测量精度降低。针对各类型网络分析仪,通过补偿网络分析仪的时间延迟,结合具体实例,得出了补偿时间延迟之后,测量结果不确定度的评定。方法表明。在网络分析仪测试电缆的常规方法基础上,可以更加准确地进行电缆损耗的测量,具有广阔的应用前景。     

一种图象识别神经网络的全硬件实现

本文介绍了神经网络的全硬件实现方法，采用数字脉冲形式，设计了一个全硬件实现的神经网络图象识别系统，提供了数字脉冲神经元电路的设计方法。网络分为三层，采取层内有互连的前向，组合式网络结构，不同层中的神经元不同，同一层中也有不同的元，它们之间存在相互连接。     

喀呖声测试脉冲信号的实现与应用

断续干扰分析仪(又称喀呖声分析仪)是家电产品电磁兼容测试的重要设备之一,文章采用基于labview可视化编程技术的函数信号发生器生成方法实现了GB/T 6113.101-2016中所规定的24种测试喀呖声分析仪的脉冲信号,并利用数字示波器波形捕获与电磁骚扰测量接收机断续干扰信号分析功能对所生成的各种测试脉冲信号的脉冲时...     

利用网络分析仪进行时域响应测试

本文简要介绍了时频转换的理论基础和在网络分析仪上实现的方法，并对不同的测试模式和激励方式进行了比较和分析。同时，通过一个典型电路的测试实例，进一步说明了利用网络分析仪进行时域响应测试的意义。     

提高频谱分析仪测试性能的几种方法

通过分析频谱分析仪基本工作原理和主要用途，结合实际测试工作中的经验，总结了优化频谱分析仪设置、提高频谱分析仪测试性能的几种方法。     

TR组件测试系统功率参数校准技术

研究工作状态下TR组件测试系统功率参数的校准方法,介绍了在脉冲峰值功率条件下功率参数测量标准的仪器组成,分析其功率参数校准的定标方法,并给出相应实验数据。     

基于CPLD的单半正弦脉冲发生器的设计

为了能够满足对振动台进行冲击测试的需求,利用CPLD实现了输出单半正弦脉冲,解决了单脉冲信号输出的控制问题。系统使用VHDL编制程序并加以D/A转换芯片、可调增益控制器等构成。试验表明用该方法生成的脉冲波形无失真、可调节脉宽范围1ms～20ms,幅值稳定可调,可用于振动台的冲击测试实验,也非常适用于实验教学和其它科研工作。     

A calibration and measurement method of a tri-six-port networkanalyzer suitable for on-wafer characterization of three-port devices

A calibration and measurement method using a wideband tri-six-port network and analyzer (TSPNA) is proposed. The scattering parameters of a three-port device under test are found to be the unknowns of a set of nine simultaneous complex linear equations. These equations are established via a group of three calibrated linearly independent excitations. No isolators are required for calibration and measurement procedures. Three unknown reciprocal two-port standards are needed for the calibration of the TSPNA. The proposed method is rigorous, explicit, and suitable for wideband on-wafer three-port device S-parameter measurements. It can easily be adapted for heterodyne automated network analyzers equipped with three reflection test-set units     

FPGA-Based Multiple-Channel Vibration Analyzer for Industrial Applications in Induction Motor Failure Detection

Early detection of failures in equipment is one of the most important concerns to industry. Many techniques have been developed for early failure detection in induction motors. There is the necessity of low-cost instrumentation for online multichannel measurement and analysis of vibration in the frequency domain, and this could be fixed to the machine for continuous monitoring to provide a reliable continuous diagnosis without needing trained staff. Field-programmable gate arrays (FPGAs) are distinguished by being very fast and highly reconfigurable devices, allowing the development of scalable parallel architectures for multichannel analysis without changing the internal hardware. The novelty of this work is the development of a low-cost FPGA based on a multichannel vibration analyzer; this is capable of providing an automatic diagnosis of the motor state carrying out online continuous monitoring. To test the functionality of the proposed vibration analyzer, three experiments on 746-W (1-hp) induction motors were carried out. Such experiments are intended to detect motor failures such as broken bars, unbalance, and looseness. The obtained results show the overall system performance.      

基于矢量误差修正的实时负载牵引测量模型方法

提出了一种新型基于矢量误差修正的负载牵引测量模型方法。相比于传统负载牵引测量系统,该方法从8-term矢量误差模型入手,建立接收机与被测件端口处电压波的函数关系,通过对矢量网络分析仪进行矢量校准和对内部接收机进行一次绝对功率校准,可实时测量被测件的输入/负载反射系数,输入/输出功率及功率增益、效率等。按照模型方法搭建了相应的硬件系统,与商用Focus的类似系统进行了比较验证,实验结果表明具有良好的效果,证明了所提方法的准确性。     

LRR-a self-calibration technique for the calibration of vector network analyzers

A new self-calibration procedure, the LRR method, for the calibration of vector network analyzers is presented. The calibration circuits consist of partly unknown standards, where L symbolizes a line element and R represents a symmetrical reflection standard. In contrast to the thru reflect line (TRL) method, which needs a line-standard with a different length than the other calibration standards, the calibration circuits of the LRR method are all of equal mechanical length. This is advantageous because the connectors of the vector network analyzer do not, thus, have to be placed at different distances from each other during calibration. In addition, the complexity of the test fixture can be reduced. The robust functionality of the LRR method is confirmed by measurements.     

A six-port network analyzer load-pull system for active load tuning

An experimental six-port network analyzer has been used as a load-pull system in an active load tuning configuration. It is shown that by using a dual six-port reflectometer and an appropriate calibration procedure, it is possible to measure at the same reference plane the ratio between the incident and reflected waves and the power flow at the output of the test transistor. Using these two values the simulated load impedance seen by a transistor and the microwave power delivered to the simulated load are calculated. Experimental results on microwave transistor characterization confirm the validity of this method. This technique uses less hardware than conventional methods, and presents a comparable accuracy to conventional techniques     

Simple photomultiplier tube internal-gating method for use in subnanosecond time-resolved spectroscopy

We propose a simple photomultiplier tube (PMT) internal-gating method for use in the field of subnanosecond time-resolved spectroscopy. In the proposed method, we control two dynodes in the PMT by applying a gate signal whose pulse width is Tg. When controlling the mth and the n(> m)th dynodes, a resolution time delta t is approximately given by delta t = Tg-(n-m) tau, where tau is a transit time of a lump of secondary electrons traveling between the two dynodes in the PMT. In principle, the resolution time delta t shorter than the pulse width Tg of the gate signal can be easily obtained. From a fundamental performance test, we found that a subnanosecond resolution time delta t = 0.31 ns was obtained for the case of m = 2 and n = 5. To demonstrate the effectiveness of the proposed method, we carried out a time-resolved spectroscopic measurement of emission obtained from a white-light-emitting diode (LED) driven by a nanosecond current pulse.     

脉冲电流条件下Ni箔流动应力及其尺寸效应的神经网络模型

目的揭示脉冲电流对金属箔材室温流动应力及其尺寸效应的影响规律,构建脉冲条件下Ni箔室温塑性流动的本构模型。方法采用单向拉伸试验,测试不同试样尺寸的Ni箔在不同电流密度条件下的单向拉伸性能。根据本构方程的输入、输出参数,设计BP神经网络结构,并利用试验数据对其进行训练及预测精度检验。结果单向拉伸试验结果表明,箔材厚度与晶粒尺寸之比及变形过程中引入的脉冲电流均会对材料的流动应力产生显著影响,且其影响规律高度复杂。脉冲电流条件下,构建的金属箔材流动应力尺寸效应神经网络模型,其预测相对误差控制在6%以内,相关系数R达到0.99。结论该神经网络模型准确描述了脉冲电流条件下金属Ni箔流动应力尺寸效应,为该材料塑性变形过程分析及合理制定工艺参数奠定了理论基础。