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Instrumentation and Measurement, IEEE Transactions on

Issue 1 • Date March 1985

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Displaying Results 1 - 25 of 35
  • Table of contents

    Page(s): c1
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    Freely Available from IEEE
  • IEEE Instrumentation and Measurement Society

    Page(s): c2
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    Freely Available from IEEE
  • Editorial on the Emancipation of Metrologists from the Laboratory

    Page(s): 1
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    Freely Available from IEEE
  • Digital Impedance Measurement by Generating Two Waves

    Page(s): 2 - 5
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    A digital measurement system is described which measures the voltages across a voltage divider consisting of a reference resistor and the unknown impedance. The voltages across reference and unknown are converted so that their magnitude and phase are digitally determined. View full abstract»

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  • In-Circuit Impedance Measurement Using Current Sensing

    Page(s): 6 - 14
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    A novel approach to in-circuit measurement of resistors, capacitors, and inductors was evolved. This approach utilizes current sensing, making possible the measurement of in-circuit components which may be directly shunted by impedances as much as two to three orders of magnitude lower in impedance than the unknown. A minature clip-on probe was developed to facilitate measurements of components mounted on printed circuit boards. A compact impedance comparator was constructed which measured in-circuit components within approximately 2 to 4-percent accuracy over the following ranges: for resistance, 1.5 ?? to 1 M??; for capacitance, 100 pF to 60 ??F; and for inductance, 400 ??H to 60 H. Impedances as low as one to three orders of magnitude smaller than the measured element impedance, depending on the probe used, shunted the unknown when the stated accuracy was measured. Much of the quoted inaccuracy is due to the ??3-percent resistance and ??0.1-percent linearity tolerances of the reference resistor which was used for all measurements. View full abstract»

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  • Measurement Principles of the Reactive Current RMS Value and the Load Susceptance for Harmonic Frequency Meters

    Page(s): 14 - 17
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    The current of a nonsinusoidal source applied to a nonresistive load contains a reactive component ir which can be decreased or even wholly compensated by a shunt reactance 1-port of parameters related directly to the load susceptances for harmonic frequencies Bn?? The reactive current rms value measurement is necessary for evaluation of the possibility of the source apparent power minimization, and the load susceptance measurement is necessary for the compensating equipment design. This paper presents the measurement principles for measuring these quantities. View full abstract»

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  • Dielectric Thickness Measurement Employing Heterodyne Technique

    Page(s): 17 - 21
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    A microwave system for measuring the thickness of dielectric materials employing the heterodyne technique is described. Calibration curves relating the dc output voltage and dielectric thickness are presented for leather, glass, and cartons. The system was operated at 9 GHz. The experimental results illustrate the suitability of the technique for industrial applications. View full abstract»

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  • The Effect of Temperature on the Accuracy of Microwave Moisture Measurements on Sandstone Cores

    Page(s): 21 - 25
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    Measurements have been made to determine the effect of temperature on the accuracy of moisture measurements in round berea sandstone cores using X-band microwaves. It is shown here that a temperature variation of a few degrees in the core may introduce inaccuracies of more than 5 percent in water-content measurements. View full abstract»

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  • Computer-Aided Permittivity Measurements of Moistened and Pyrolized Materials in Strong RF Fields (Part I)

    Page(s): 25 - 31
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    This paper presents the results of computer-aided permittivity measurements (CAPM) on moistened paper samples, exposed to strong RF fields inside a microwave cavity. Permittivity measurements, sample weight, and RF power absorbed by the sample are monitored in real time by a microcomputer. From the CAPM, the permittivity values and the moisture content of the material are calculated. The effects of paper pyrolization on the permittivity measurements are examined, and a reversal in the measured dielectric parameters is observed at the 0-percent moisture level. This CAPM method is useful to examine the dielectric properties of materials critically dependent on the moisture content, for example, in food products and in the telephone wire industry where the insulating material is obtained from dried paper pulp. In addition, this CAPM technique can be applied to study the effects of thermal and RF shocks in dielectric materials such as used in high-power microwave windows or in studying the biological effects of microwave radiation using both short and long exposure cycles. View full abstract»

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  • Optical Reflectance Sensor Measures Displacement in Magnetic Suspension

    Page(s): 31 - 34
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    In active magnetic suspension systems, electromagnetic forces are used to keep a body in stable equilibrium without mechanical contact. Basically, an active magnetic suspension is a position servomechanism. Thus, accurate measurement of the position of the levitated part is important. A variety of displacement transducers has been in use, the eddycurrent sensor being the most favored one at present. This paper describes an optical reflectance sensor used in a novel configuration to measure the position in a levitation setup. A sensitivity of 10.5 V/mm, and a linearity range of about 0.5 mm, were obtained by this method. The sensor and the measurement technique are described in detail here. View full abstract»

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  • Characteristics of Vacuo-Thermojunctions at Ultra-Low Frequency

    Page(s): 34 - 41
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    Characteristics of vacuo-thermo-junctions (VTJ's) at ultra-low frequency are discussed. A method of expansion with series of nonharmonic sine functions has been combined with a method of perturbation to solve the partial differential equation for heat conduction in the heater of a vacuo-thermojunction. Theoretical results have been checked by experiments in which both a photorecorder and a method of Lissajous figures have been used to analyze the amplitude variations and the time lags of thermo-electromotive force (TEMF) and voltage drop through the heater versus its current. View full abstract»

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  • Edge Corrections for Strip and Disc Capacitors

    Page(s): 41 - 47
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    We present a precise numerical method for calculating the edge correction for a long rectangular plate capacitor, and compare the results with available approximate formulas. We give numerical results for the disc capacitor which are much more accurate than the approximate formulas at low capacitances (a/h <100, where a = radius and h = separation). These results match or surpass the precision of present-day capacitance bridges. We discuss the difficulties encountered in attempting to extend the work to larger a/h ratios. View full abstract»

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  • Simulation of the Steady-State Behavior of Crystal-Controlled Oscillators Using the WATAND Computer-Aided Design Program

    Page(s): 47 - 51
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    The WATAND computer-aided design package has been used to successfully simulate the steady-state response of crystal-controlled oscillators. The WATAND program contains a routine that allows the steady-state response of a nonlinear dynamic circuit with slow transients to be found without the lengthy and uneconomical process of integrating in the time from t = 0. Oscillators simulated were the following: an LC oscillator with discrete components; and three crystal-controlled oscillators, one with silicon integrated circuits and two with discrete components, one having an external tank. To simulate some of these oscillator circuits, some of the algorithms in WATAND had to be modified. Suggestions for further improvements in oscillator simulation are also made. View full abstract»

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  • Uniformity Measurements Using Focal Plane Targets

    Page(s): 51 - 54
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    A test technique for measuring the uniformity of an electrooptical imaging device is presented. The technique consists of using standard targets such as large aperture and four-bar targets located in the focal plane of a collimator. Thus, the need for a separate, large uniform target is eliminated. Experimental results for a vidicon camera and for a CCD camera show that the large aperture target is a better choice than the four-bar target. View full abstract»

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  • An Ultra-Low Drift Amplifier Using a New Type of Series-Shunt MOSFET Chopper

    Page(s): 54 - 58
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    A chopper amplifier of a new type is proposed for the amplification of nanovolt-order dc voltage. The chopper is built by connecting a shunt switch, which is driven at twice the chopper frequency, to the output terminals of a conventional and balanced-type series-shunt MOSFET chopper. The present chopper is free from offset voltage arising from spike voltages and has an input voltage offset temperature coefficient of less than 0.1 nV/??C for a signal source of less than 1 k??, and a long-term drift of 2 nV/18 h for signal source resistance of 6.1 ??. View full abstract»

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  • Measurement of Operational Amplifier Characteristics in the Frequency Domain

    Page(s): 59 - 64
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    A test circuit for the automatic measurement of integrated-circuit operational amplifiers in the frequency domain has been developed. The main advantage of this test circuit over those previously reported in the literature is that it uses buffers in the feedback loop to reduce the influence of the output impedance of the operational amplifier. A fit program has been developed to extract the relevant parameters such as the transfer characteristics, the common mode rejection ratio, and the power supply rejection ratio. Examples of measurements are added for several operational amplifiers. View full abstract»

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  • Linear Least-Squares Determination of Doppler Time Derivative for NAVSPASUR-Like Signals

    Page(s): 64 - 69
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    A method is derived for optimum estimation of doppler, doppler time derivative, and other parameters for doppler-type radar returns, using linear least-squares estimation procedures. It is used on radar returns from the Naval Space Surveillance System to obtain improvement of at least one order of magnitude in doppler measurement from previous practice; doppler derivative has been measured for the first time. The accurate measurement of doppler derivative (typically ??0.2 Hz2) has enabled a resolution of the inherent geometric degeneracy in the coplanar NAVSPASUR system, to provide a significant improvement in single-pass orbit determination accuracy. View full abstract»

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  • General Time Domain Analysis of T.D.S. Data: Application to Liquid Crystals

    Page(s): 70 - 74
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    In this paper, an automatic two-channel Time-Domain Spectroscopy (T.D.S.) system is reported. The data analysis is achieved in "real time" by using a numerical method without prior assumptions as to the form of the incident voltage pulse form or to the physical relaxation mechanisms. Two cases are treated: the lumped capacitance and the coaxial line. The method is applied to investigate the dielectric behavior of liquid crystals with the help of original cells requiring very small sample volume. With great reductions in time and efforts, the results deduced with this T.D.R. system are in very good agreement with those previously obtained by classical frequency-domain measurements. View full abstract»

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  • A CCD-Based Real-Time Spectrum Analyzer for Incoherent Scatter Radar Systems

    Page(s): 75 - 78
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    A real-time spectrum analyzer based on a charge-coupled device (CCD) is described. The power spectrum is calculated by the chirp z-transforn using the CCD. The analyzer includes a buffer memory for the input data and an integrator to sum the computed spectral estimates for better statistical accuracy. The analyzer makes one 512-point, discrete Fourier Transform (DFT) for complex data in 1.024 ms. View full abstract»

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  • Principles of Automatic Alignment and Calibration Using Embedded Microcomputers

    Page(s): 78 - 80
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    Alignment and calibration of any system manually or automatically can be reduced to a control problem; hence the powerful theories, rules, and methods of all areas of control engineering can help designers incorporate automatic alignment and calibration in systems with embedded microcomputers. This paper presents the very basic relationship between alignment/calibration and control theory. An example of zeroing an amplifier using a single chip microcomputer illustrates the proposed concepts. View full abstract»

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  • Telemetric Seismic Data-Acquisition System

    Page(s): 81 - 84
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    A system comprising digital telemetry remote stations and an on-line event detection and data recording station has been developed. The remote stations employ time-division multiplexing of up to three seismic sensors operating at sampling rates of 60 samples/s. Higher sampling rates are available if fewer sensors are used per station. The highest single-sensor sampling rate is 240 samples/s. Companding ??-255 law analog-to-digital conversion is performed on-site utilizing an eight-bit transmission format and exhibiting a 72-dB dynamic range. Event detection at a data collection station has been implemented on a microprocessor, which also handles data acquisition and synchronization with a standard-time clock. A slave microprocessor controls data transmission via telephone lines and data recording on magnetic tapes employing a standard format to permit off-line data analysis on a computer. Three digital-to-analog output channels are provided for on-line signal monitoring. View full abstract»

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  • A Linear Thermistor-Based Temperature-to-Frequency Converter Using a Delay Network

    Page(s): 85 - 86
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    A novel thermistor-based temperature-to-frequency converter, using a delay network, is described which exhibits linear input/ output relation over the range 253-523K with a conversion sensitivity of 14.7 Hz/K and maximum deviations of 4.8 percent at 523K and 1.2 percent at 248K. Analytical expressions for system performance are obtained and verified experimentally. The circuit adjustment is performed simply and quickly at room temperature. View full abstract»

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  • A Simple Current-To-Time Converter

    Page(s): 87 - 88
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    A simple circuit based on one CMOS two-input or gate serving as a voltage discriminator, a waveshaping circuit, and a logic circuit is described. It produces pulses with a pulse pause proportional to the reciprocal of its input current. If covers three decades, 1 ??A to 1 mA, with the conversion error less than 1 percent or five decades, 1 ??A to 10 mA, with the error less than 3 percent. View full abstract»

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  • Simultaneous Determination of Transistor Noise, Gain, and Scattering Parameters for Amplifier Design through Noise Figure Measurements Only

    Page(s): 89 - 91
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    A method for the simultaneous determination of transistor noise and gain parameters through noise figure measurements has been presented recently. An improved version of the method is presented here which can also yield all the scattering parameters needed for designing amplifiers. By means of a proper (computer-aided) data-processing technique, s11, s22, |s12| , |S21|, and s12s21 are determined. As experimental verifications, the characterization of a GaAs MESFET versus frequency (4-8 GHz) is reported. View full abstract»

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  • The Generation of Accurate, Drift-Free, Frequency-Weighted, Pseudo-Random Audio Noise

    Page(s): 91 - 93
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    A method is given to generate and analyze frequency-weighted pseudo-random audio noise. The only analog elements are a digital-to-analog converter and a simple interpolating filter. The method is attractive because it easily accomodates arbitrary spectra and equalization of any known frequency dependent elements subsequent to the source. A method is given to analyze the effects of a finite word length on the output spectrum. View full abstract»

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Aims & Scope

Papers are sought that address innovative solutions to the development and use of electrical and electronic instruments and equipment to measure, monitor and/or record physical phenomena for the purpose of advancing measurement science, methods, functionality and applications.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Prof. Alessandro Ferrero
Dipartimento di Elettrotecnica
Piazza Leonardo da Vinci 32
Politecnico di Milano
Milano 20133 Italy
alessandro.ferrero@polimi.it
Phone: 39-02-2399-3751
Fax: 39-02-2399-3703