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Instrumentation and Measurement, IEEE Transactions on

Issue 4 • Date Dec. 1986

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Displaying Results 1 - 25 of 33
  • [Front cover]

    Page(s): c1
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    Freely Available from IEEE
  • [Front inside cover]

    Page(s): c2
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    Freely Available from IEEE
  • What is an appropriate curriculum for graduate study in instrumentation?

    Page(s): 545
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    Freely Available from IEEE
  • Announcing 1985 prize paper award winner

    Page(s): 546
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    Freely Available from IEEE
  • A novel peak amplitude and time detector for narrow pulse signals

    Page(s): 547 - 550
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    The requirements for a peak amplitude and time detector for applications such as time-of-flight mass spectrometers are derived. A nonlinear feedback structure is found best suited to meet these demands. The novel structure is analyzed and optimized with respect to the ideal behavior and the influence of parasitics. Based on the results, a thick-film hybrid peak detector with an integral nonlinearity of less than 0.3 percent is presented. The output signal varies with pulse shape and pulsewidth (10–250 ns) by less than 10 percent within a pulse amplitude range of 50 dB. View full abstract»

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  • A switched-battery digital capacitance meter

    Page(s): 551 - 554
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    A digital capacitance meter based on the RC discharge with battery voltage polarity switching is described. The meter parameters — resolution, linearity, and accuracy — have very low sensitivity to variations in internal meter circuits and to changes of internal switch parameters. Automatic control of changing phase timing reduces the initial condition error of the measurements. The proposed meter is intended for use in applications where precise measurements of small capacitance changes are required. View full abstract»

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  • A switched-capacitor digital capacitance meter

    Page(s): 555 - 559
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    A digital capacitance meter has been developed based on the switched-capacitor cyclic analog-to-digital (A/D) converter. It consists of the analog arithmetic and sample/hold (S/H) circuits. The arithmetic circuit first samples the capacitance to be measured in a form of its proportional voltage. This voltage is then converted into a binary number by the A/D converter. The whole operation is insensitive to parasitic capacitances, offset voltages of op amps, and the capacitance mismatch involved in the circuit. Therefore, the proposed meter permits an accurate capacitance measurement. Error analysis shows that 12-bit accuracy can be expected by realizing the meter in an IC form. A prototype meter built using discrete components and examples of measurement are also given. View full abstract»

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  • Microprocessor-based resistance measurement

    Page(s): 560 - 565
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    The paper deals with microprocessor-based resistance measurement of electrical RL circuits by sampling values of the current and voltage. Special attention is paid to the relation between the time required for this measurement and the accuracy attained. This is a problem associated with circuits having a very high electrical time constant, such as windings of large transformers or superconducting coils. The suggested method permits shortening of the required resistance measurement time, which in turn realizes a significant overall time saving. In addition, it permits overcoming essential measurement errors which may occur when the test is performed during a thermal transient. Different measurement errors are analyzed and a statistical method which leads to significant improvement of the result is presented. View full abstract»

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  • A novel digital frequency multiplier

    Page(s): 566 - 570
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    This paper presents a digital frequency multiplier having many features not yet found together in existing multipliers. Its acquisition time is within one period of the input signal and it can follow the input frequency over more than three decades. The relative frequency error on its synchronized output signal is independent of the multiplication factor N and is noncumulative. The maximum value of this error is given by fin/fc where fin is the input frequency and fc a master clock frequency. This represents a decrease in the error value by a factor N over many existing digital frequency multipliers. View full abstract»

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  • Low-power temperature detector and rate of temperature change detector

    Page(s): 571 - 575
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    A temperature detection switch and a “rate of temperature change” detection switch are designed by using the dependence of the inverse saturation current of the p-n junction on temperature. This current is compared to the constant reference current in the case of the temperature detector or, for the detector of the rate of temperature change, to the inverse saturation current of another p-n junction, having different thermal time constant and different junction area. Relying upon the shape of the static characteristic of the constant reference current source, realized in a usual manner, and the inversely polarized p-n junction, the low-power current comparator is realized by a simple series connection of the current sources, with the supply voltage applied at the end points and the detector output voltage derived from the midpoint. Besides describing the operating principle, the paper contains the analysis of the thermal model of the switches and the accuracy investigations. The design criteria are experimentally confirmed. Due to their accuracy (0.1°C), simplicity, and extremely low power consumption (supply current is less than 10 μA), present detectors are especially suitable for applications in fire alarms. View full abstract»

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  • A coaxial calorimeter and its use as a reference standard in an automated microwave power calibration system

    Page(s): 576 - 579
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    The construction of a dc-substitution coaxial calorimeter having 7-mm-diameter input line is described and an evaluation of its uncertainty is presented. An automated procedure is then outlined for calibrating a power transfer standard against the calorimeter. The transfer standard consists of a directional coupler with a thermistor mount on its side arm. The power transfer standard can in turn be used for automated calibration of thermistor mounts and other power sensors. The overall estimated uncertainty (expressed as one standard deviation) of the measurement of the effective efficiency of a thermistor mount varies from 0.2 percent at 2 GHz to 0.4 percent at 18 GHz. View full abstract»

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  • A thermoresistive AC-DC transfer element

    Page(s): 580 - 584
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    A thermoresistive ac-to-dc transfer device has been reduced to practice by using an indirectly heated sensing element having a high-temperature coefficient of resistance to determine the heating power of input signal. Precise ac-to-dc transfer measurements were made beyond 100 MHz over serverai octaves of square-law response. The thermoresistive transfer converter (TRC) is inexpensive to manufacture and is usable in conventional 200-Ω/V 5-mA systems. The TRC employs continuous contact of the sensing element along the heater and therefore presents an alternative to the multijunction thermal converter (MJTC) for improved precision ac metrology. View full abstract»

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  • Model of a fast vision detector for determination of the velocity of a moving object

    Page(s): 585 - 590
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    A model of a vision detector is described for the measurement of velocity of a moving object with reduced computing time. The detector is designed utilizing four linear arrays of imaging charge-coupled devices (CCD's) where the activation of each CCD is controlled by means of a threshold detector (TD) via a computer and external circuits. In comparison to the conventional two-dimensional (area) detector, this model would simplify the complexity of motion detection, and would lead to a significant reduction in required memory length and computation time of a computer. Theoretical analysis demonstrates the model's capability to uniquely determine the magnitude and direction of the velocity of a moving object for an arbitrary direction of motion. View full abstract»

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  • Dynamic performance of digital recorders used for monitoring high-voltage impulse tests

    Page(s): 591 - 595
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    Frequency- and time-domain characteristics of digital transient recorders (in short, digitizers) are discussed in order to establish the requirements on digitizers used for high-voltage testing. Results of an experimental study performed on a 200-MHz 8-bit digitizer are presented and related to the design features of this instrument. The inherent design characteristics and their influence on the digitizer dynamic performance are analyzed in view of simulation of the digitizer through a computer model. View full abstract»

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  • A portable high-speed digital image processing instrument for the enhancement of television images

    Page(s): 596 - 605
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    It is known that digital images may be usefully enhanced using two-dimensional (2D) recursive filters. The associated digital filter algorithms must have acceptable word lengths and be implement-able over the entire image at an acceptable processing speed. Spatial-integrator 2D filtering algorithms and recursion along diagonal lines of pixels are used to permit the design and construction of a fast, portable, and low-cost television image-enhancement instrument. Menu-driven software permits the nonspecialist user to enhance television images in less than 4 s using any of 27 different 2D filter transfer functions. View full abstract»

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  • Computer-aided permittivity measurements of moistened and pyrolized materials in strong RF fields (part II)

    Page(s): 606 - 611
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    In a previous paper [1], we proposed a computer-aided permittivity measurements (CAPM) system and presented the results on moistened paper samples, exposed to strong RF fields inside a microwave cavity. In this paper, we further develop the proposed CAPM system and present the results of permittivity measurements on moistened wood and ceramic samples. A method to correct the measured sample weight for the effects of the microwave leakage radiation pressure is described. The achievement of optimum heating and drying rates is discussed in detail. A block diagram of overall computational procedure for permittivity measurements by using the CAPM system is illustrated. In addition, the measurements error analysis is pursued according to the computational procedure. View full abstract»

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  • An analysis algorithm for thermal detectors of radiation

    Page(s): 612 - 618
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    The response of a thermal detector to an input signal is characterized by an exponential approach to the steady-state level. Moreover, since this device is rather sensitive to external conditions, the measured signal is perturbed by noise and thermal drift. An algorithm, based on optimization techniques, is presented for determining the responsivity of the detector (calibration stage) or the input radiant power (actual measurement) from the measured data. Some examples on the algorithm performances are carried out in different experimental situations. View full abstract»

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  • Nondestructive eddy current testing for the measurement of conductivity and surface buckling of metallic sheets

    Page(s): 619 - 623
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    A cylindrical excitation coil, fed with ac current, is put in front of a metallic or ferromagnetic sheet. Closed formulae for the vector potential in the space and the change of the impedance of the exciting coil are given. The results are developed to show the effect of the geometrical properties of the measuring system upon the test of the buckling of the sheet, its material purity, and its conductivity. The phase angle rather than the amplitude of the change in the coil impedance is taken as the measured parameter. View full abstract»

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  • A precision densimeter which compensates for liquid viscosity

    Page(s): 624 - 629
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    This paper describes a new densimeter, consisting of a compact pencil-sized density detector probe and a microprocessor-based display unit. The densimeter measures densities in the range 650-1500 kg/m3 to an accuracy of ±0.5 kg/m3, and automatically compensates for liquid viscosities up to 1 N · s/m2. The densimeter measures liquid density by the natural frequency of a thin-walled cylinder at the tip of the probe. The natural frequency varies with the density of the liquid the probe tip is immersed in. Viscosity of the liquid also affects the natural frequency of the cylinder immersed in it, as well as the amplitude of oscillation. The detector measures both the frequency and the Q factor at resonance, and uses this information to compensate for the effects of liquid viscosity. View full abstract»

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  • Oil and water content measurement of sandstone cores using microwave measurement techniques

    Page(s): 630 - 637
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    A microwave measurement technique is proposed for determining the water and oil content of a berea sandstone core by measuring the attenuation and phase shift of an electromagnetic (EM) wave traveling through the sandstone core. The frequency oif the applied electric field is 10.5 GHz. The water content of the core is determined by the attenuation of the EM wave, while the phase shift of the EM wave is used to determine the oil content. It is found that the water content can be determined with an uncertainty of less than ±5 percent, while oil content can be found within ±8 percent of the actual values for most of the cores used for measurement purposes. The attenuation and the phase shift of the EM wave in traveling through the sandstone core are measured using a microwave bridge circuit. View full abstract»

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  • A novel digital power-factor meter design

    Page(s): 638 - 640
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    This paper describes a novel design for a digital power-factor (PF) meter. The design is based on a new digital processor that gives an output frequency proportional to its input voltage, as well as a digital output inversely proportional to the input voltage. The output frequency is made directly proportional to the product of the peak voltage and the power factor Vm cos ⊘, while the digital output is inversely proportional to the peak voltage Vm. The digital and frequency outputs are applied to a binary rate multiplier (BRM). The BRM frequency output is summed over a specified period of time to provide PF information. View full abstract»

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  • A new simple technique for capacitance measurement

    Page(s): 640 - 642
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    A new and simple technique for capacitance measurement is presented. It uses a dc supply, and capacitance is measured using a single resistance variation. Experimental results confirm the theory developed. View full abstract»

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  • High-stability DC-current source using NMR lock technique

    Page(s): 642 - 643
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    A high-stability constant current source has been developed using the nuclear magnetic resonance (NMR) field-frequency lock technique. The current is locked to the NMR frequency via the magnetic field of the electromagnet which has a highly stable coil constant. The current of 1 A has been stabilized to better than 0.2 ppm/h. View full abstract»

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  • Bipolar and bilateral voltage-current/current-voltage converters using operational amplifiers in summing mode

    Page(s): 644 - 646
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    A practical bipolar, bilateral voltage-source to current-source converter scheme using two operational amplifiers (OA's) in summing mode is described. The scheme also behaves as a current-voltage (I-V) converter when certain specific constraints are observed. The summing mode application of OA's has its effect on the range of operation whose safe limits are discussed. The scheme is versatile, is largely insensitive to supply voltage variations, and can be used with conversion factor scaling for the desired output range with a specific input range excursion. View full abstract»

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  • Measurement of spatial variation of responsiveness in solid-state imager

    Page(s): 646 - 648
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    An experimental setup that provides the measurement of the spatial variation of the responsiveness of a single photodiode belonging to a linear metal-oxide-semiconductor (MOS) photoarray is described. An optical microscanning technique has been employed to sequentially illuminate a small area of a single photoelement in order to achieve the mapping of its spatial responsiveness. Experimental results for a single pixel are graphically presented. 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.

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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