共查询到20条相似文献,搜索用时 672 毫秒
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Massicotte D. Legendre S. Barwicz A. 《IEEE transactions on instrumentation and measurement》1998,47(2):362-370
The problem of applying the neural networks for static calibration of measuring systems and for measurand reconstruction is addressed. A multilayered neural network based method for the static calibration of this system is proposed. The functioning of the calibrated measuring system is based on three fiber-optic transducers whose static characteristics are nonmonotonic and significantly influenced by temperature. The applicability of the proposed calibration method is demonstrated in the case under consideration using synthetic and real data. The neural network is designed and implemented in a general purpose microcontroller. In comparison with the spline-based method of calibration, for the same reference data, the proposed method allows obtention of a better quality of calibration and, most important, when calibrated, the multilayered neural network does not require the measurement of temperature for pressure reconstruction 相似文献
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《IEEE transactions on instrumentation and measurement》2003,52(4):1030-1034
This paper proposes a method to measure the in-band deterministic and stochastic contributions of nonlinear distortions in mixers. The model of the mixer as a two- or three-port device is developed. Based on this model, the measurement technique-which is a generalization of the methods developed for amplifiers-is developed. While designing the measurement method, the difficulties that arise out of the fundamental differences between mixers (three-port devices) and amplifiers (two-port devices) are taken into account. Two techniques are presented, depending on the fact that the phase of the local oscillator is known or unknown. 相似文献
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现有高频段在片S参数校准方法有16-term误差模型校准方法和基于多线TRL的二次串扰修正算法,它们对测试系统之间的串扰误差进行了较好的表征。提出了一种新型校准方法,即把测试系统之间的串扰等效为一个与被测件并联的二端口网络。整个校准方法一共分为两步,第一步采用常规的SOLR校准方法得到基本8项误差模型,第二步通过测量一个串扰标准件(可以是SOLR中的开路校准件)完成对串扰误差的表征。仿真和测试结果表明,新型校准方法准确度可达到16-term误差模型的准确度,并对串扰误差具有相当的抑制效果。同时,新模型方法只需使用4个校准件,数量少于传统16-term误差模型方法,在保证准确度的前提下,提高了测试效率。 相似文献
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Errors analysis of transponder-based radiometric calibration for high-resolution imaging radars 总被引:1,自引:0,他引:1
Calibration is often required for precision measurement instruments like synthetic aperture radar (SAR) such that an image pixel intensity is directly expressed in terms of the surface backscatter coefficient. An active reflector named as transponder is an effective SAR calibration device which yields a larger radar cross-section than a corner reflector. Likewise, encoding the retransmitted signal can decouple the transponder from the background scatterers, hence, it can be used to calibrate SAR for radiometry, polarimetry and interferometry. However, as this transponder acts as an amplitude modulator, any signal errors in the transponder will result in degraded performance of radiation calibration. Literature search reveals that little work has been reported. As such, various kinds of signal errors and their effects on radiometric calibration are investigated. The system configuration and corresponding signal processing algorithms are detailed. Starting with an investigation of different errors, closed analytic expressions for calibration performance are derived. Furthermore, the most essential element of this transponder, one X-band wideband voltage-controlled attenuator, is developed. Experimental results show that, because of its low cost and wideband modulation technique, this transponder has extensive applications, not just for radiometric calibration. 相似文献
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An improved method of network analyzer calibration is described using the 15-term full model which includes all leakage errors between on-wafer probe tips. This model is well suited to eliminate measurement errors of network analyzer measurements on the wafer. All procedures presented are so-called self-calibration methods, allowing for standards that are not completely known. This allows one to create calibration standards in an easy way and to monitor the calibration process. Simple and robust closed-form equations are presented for all procedures. All procedures can be derived from the general method MURN (match, unknown, reflect, network). The MORN (match, open, reflect, network) is presented, which is particular interesting for on-wafer-measurements. Furthermore, the TMRN (through, match, reflect, network) procedure presented is especially designed for coaxial measurement problems. Experimental results of the TMRN method attest to the very good accuracy and viability of the 15-term self-calibration procedures and can be compared with other 15-term procedures 相似文献
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A three-port nonlinear vectorial network analyzer (NVNA) is presented. This new measurement instrument allows designers to measure for the first time the full nonlinear three-port behavior for any arbitrary mixer. The usefulness of the three-port NVNA is proven on amplitude and phase calibrated three-port measurements of a microwave mixer. 相似文献
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《Science, Measurement & Technology, IET》2008,2(5):359-366
The authors demonstrate how a transmitter (Tx), a reciprocal transmitter/receiver (Tx/Rx) signal path and two unidirectional receiver (Rx) paths can be used together with short, open, and load standards for the absolute vector error correction (AVEC) of a Tx/Rx module. Once calibrated, this Tx/Rx module can then provide accurate vector measurements of the signals that are flowing into and/or out of the test port. This novel AVEC technique is one of the key concepts in the design of a wideband absolute vector signal measurement system, which overcomes the limitations of traditional measurement instruments by combining the features of vector signal analysers, spectrum analysers, and vector network analysers. The AVEC method is validated using numerical simulation data for a simplified baseband test circuit. The AVEC technique is then extended to the calibration of wideband, high-frequency Tx/Rx modules that involve frequency up/down conversion mixers in a follow-on paper 相似文献
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介绍一种浮空器气囊体积测量装置的现场校准方法,通过设定现场校准区域,构建地面控制点的局部三维坐标;在被测对象侧边的6个地面控制点设立测站,用激光全站仪和棱镜组件按照极坐标法观察得到被测对象侧边精密标定杆上所有准校点的局部三维坐标,建立校准参考坐标系,构建完整的现场校准场。测量装置对在校准参考坐标系中的精密标定杆上校准点进行拍摄获得图片,解算得到测量装置的每个相机的外方位元素,得到其位置和姿态,完成校准工作。本文提出的现场校准方法解决了测量装置在任意场景下浮空器囊体体积测量的应用问题和测量装置使用中需要搬动情况下的校准问题。 相似文献
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G. E. Mattingly 《Journal of research of the National Institute of Standards and Technology》1992,97(5):509-531
Critical measurement performance of fluid flowmeters requires proper and quantified verification data. These data should be generated using calibration and traceability techniques established for these verification purposes. In these calibration techniques, the calibration facility should be well-characterized and its components and performance properly traced to pertinent higher standards. The use of this calibrator to calibrate flowmeters should be appropriately established and the manner in which the calibrated flowmeter is used should be specified in accord with the conditions of the calibration.These three steps: 1) characterizing the calibration facility itself, 2) using the characterized facility to calibrate a flowmeter, and 3) using the calibrated flowmeter to make a measurement are described and the pertinent equations are given for an encoded-stroke, piston displacement-type calibrator and a pulsed output flowmeter. It is concluded that, given these equations and proper instrumentation of this type of calibrator, very high levels of performance can be attained and, in turn, these can be used to achieve high fluid flow rate measurement accuracy with pulsed output flowmeters. 相似文献
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为提高大口径管道流量在线校准的准确度,建立了一套多声道超声测流装置,对其现场探头定位安装及几何测量方法进行了优化,并在研究流量计算模型的基础上进行了不同探头插入状态的实验室测试。在DN400的管道上安装交叉4声道超声探头,测试了3种探头插入状态,通过分析流量测量误差来得到最优化方案。实验表明,探头插入状态显著影响装置流量测量误差,随着插入深度的增加流量测量结果逐渐增大,但即使全突状态流量依然偏小;3种状态中全缩线性较好,经过系数修正后,全缩状态下超声测流装置计量准确性最高,达到0.2级;超声测流装置经过实验室测试与优化,可以满足1.0级大口径管道流量在线校准的要求。 相似文献
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针对低温液位传感器校准装置的夹具端空间姿态问题,提出了一种基于多边法原理的误差辨识方法。利用激光跟踪仪测距精度高的特点,采用多边法原理对校准装置夹具端的运动轨迹进行标定,以重力加速度方向为Z轴反方向建立虚拟坐标系,利用刚体中两点位置始终不变的特性,获得被测点6项误差的冗余数据,实现校准装置几何误差的辨识。仿真结果表明,所提出的方法具有一定的可行性,采用遗传算法与信赖域法、Guass-Ne叭加法相结合的方法,在一定程度上避免因初值难以确定造成的数据不收敛问题。 相似文献
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Berghoff G. Bergeault E. Huyart B. Jallet L. 《IEEE transactions on instrumentation and measurement》1997,46(5):1111-1114
The complete calibration of a double six-port network analyzer includes constants for the measurement of wave ratios (S-parameters) as well as constants for absolute power level measurements for nonlinear device characterization. This paper describes how a complete set of constants can be obtained for on-wafer measurements from a complete calibration in a coaxial measurement plane and a subsequent on-wafer calibration with the minimum number of elements 相似文献
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多层TRL校准是微波毫米波大功率器件测试中常用的一种校准方法。针对经典TRL校准方法在大功率器件测试中易出现的误差系数相位跳变问题,提出了一种结合先验知识和动态最小化误差逼近的宽带TRL校准优化算法。基于国产AV3672矢量网络分析仪和负载牵引测试系统在3.8GHz及三次谐波对该算法的有效性进行了验证。实验结果证明,该算法有效地修正了误差系数相位跳变的问题,对器件大信号工作状态最优阻抗点的分析更为准确,并且算法复杂度没有大幅增加,可以应用为经典TRL算法的后续修正步骤,具备极强的实用性和通用性。 相似文献
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This paper presents a wideband fast multipole boundary element method (FMBEM) for two dimensional acoustic design sensitivity analysis based on the direct differentiation method. The wideband fast multipole method (FMM) formed by combining the original FMM and the diagonal form FMM is used to accelerate the matrix-vector products in the boundary element analysis. The Burton–Miller formulation is used to overcome the fictitious frequency problem when using a single Helmholtz boundary integral equation for exterior boundary-value problems. The strongly singular and hypersingular integrals in the sensitivity equations can be evaluated explicitly and directly by using the piecewise constant discretization. The iterative solver GMRES is applied to accelerate the solution of the linear system of equations. A set of optimal parameters for the wideband FMBEM design sensitivity analysis are obtained by observing the performances of the wideband FMM algorithm in terms of computing time and memory usage. Numerical examples are presented to demonstrate the efficiency and validity of the proposed algorithm. 相似文献