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Instrumentation and Measurement, IEEE Transactions on

Issue 2 • Date June 1981

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Displaying Results 1 - 23 of 23
  • Table of contents

    Page(s): 1
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  • [Inside front cover]

    Page(s): c2
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  • A high-quality digital filter instrument

    Page(s): 93 - 97
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    A high-quality real-time low power dissipation 12-bit low-pass digital-filter instrument is described. It is a hardware version of a recently proposed multirate ladder structure which can be implemented entirely without digital multipliers. The frequency response of the filter is user programmable and is determined by an operating sequence stored in a read-only memory. A numerical technique is described for determining the operating sequence corresponding to a particular low-pass response. Measured frequency responses are shown for four different cutoff frequencies between 2 and 5.5 kHz) for the fifth-order filter instrument. View full abstract»

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  • Multichannel digital ventilated psychrometer using eight-bit microcomputer

    Page(s): 98 - 102
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    A multichannel digital ventilated psychrometer using an 8-bit microcomputer has been developed. It offers the advantages of direct reading of the relative humidity (RH) and the temperature from the digital indicator (or the CRT indicator) as well as multichannel use. The sensing of humidity is based on the psychrometric principle by two integrated circuit (IC) temperature transducers acting as dry and wet bulbs. The temperature of the dry bulb has a range of 0-50°C with a linearity better than 0.05°C. The temperatures of the dry and wet bulbs are converted into proportional voltages which are fed into a microcomputer after having been converted into digital form by the A/D converter. As the RH data for dry-bulb temperature and dry- and wet-bulb temperature difference have previously been stored in the memory, the corresponding RH data can be derived from using the necessary steps of the program. The results are displayed on a digital indicator. The indication shows the channel number being measured, the RH, and the dry-bulb temperature. The experimental results show that it is possible to make an apparatus to give a direct indication of RH for the multiple sensors and the accuracy of the apparatus is estimated to contain an RH error of less than 2 percent with a response time of less than 20 s. It may be used both for measurement and control of a multiple humidity environment. View full abstract»

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  • A new approach to digital frequency synthesis

    Page(s): 102 - 106
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    Presents a new technique of synthesizing frequencies in steps of 1 Hz from 1 to 399999 Hz. The synthesized waveform is a symmetrical square wave and transistor-transistor logic (TTL) compatible. The algorithm used for the synthesis allows for very efficient use of digital implementation of the system. The complete system consists of an input device, a BCD/binary converter, a binary divider, a digital comparator and a phase-locked loop (PLL) frequency multiplier. View full abstract»

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  • The double dual-slope multiplier: Elimination of offset

    Page(s): 106 - 113
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    The double dual-slope multiplier is a multiplying analog-to-digital converter based on the dual-slope integrating converter. The ratio of the product of two unknown voltages to the square of a reference voltage is obtained in terms of the ratio of a measured time interval to a known time interval. Offset errors, which are the main source of error, are described and a modification which greatly reduces the error is proposed. The errors consist of scale factor, output, and linear feedthrough errors. The scale factor and output errors can be measured by a cycle consisting of two dual-slope measurements that use the reference voltage only. The feedthrough errors can be eliminated if the multiplying cycle is repeated with the order of the inputs reversed. The operation of the multiplier when the inputs are less than the offset is considered in detail. Since the decision making, memory, and calculations necessary for the control of the multiplier and the correction of the offset are considerable, the method is mainly applicable to precision instruments equipped with a microprocessor. View full abstract»

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  • Capacitive transducer for accurate displacement control

    Page(s): 114 - 123
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    The underlying theory, design, and operation are presented for an interdigitated capacitive displacement transducer supported on an air-bearing stage. This device provides a purely electrical means of displacement measurement and offers the possibility of being closely matched to the substrate against thermal perturbations. Tests on a prototype system show the basic capacitive transducer to have a sensitivity of 2.6 mV/μm and a position uncertainty of 4 nm set by thermal noise. View full abstract»

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  • Microprocessor-controlled acquisition system for the determination of MOS transistor parameters

    Page(s): 124 - 128
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    Discusses a microprocessor-controlled data acquisition system for automated acquisition of MOS transistor parameters. The Analog Signal Processor and the Control Interface Circuit are described. Finally, the authors explain the procedure of parameter determination based on the least squares estimation criterion. This procedure is applied to long-channel, surface-channel, enhancement-mode PMOS transistors. The ID-VD curves exhibit an accuracy of 1-3 percent compared with the experimental characteristics. View full abstract»

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  • CMRR performance limits of analog multiplexers using normal-mode filters

    Page(s): 129 - 132
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    An analysis of the common-mode rejection (CMR) of low-level analog multiplexers using normal-mode filters is presented. The CMR is shown to be limited by the multiplexer bus capacitance. Simple analytical expressions are presented for predicting the CMR performance of these multiplexers. View full abstract»

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  • Phase-coherent synthesis and precision frequency measurements in the far infrared

    Page(s): 132 - 138
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    A short review of the basic concepts and problems in frequency multiplication into the infrared region of the electromagnetic spectrum is given. Results obtained with a multiplier chain starting from 5 MHz are reported. The carrier collapse is found at a frequency of about 15 THz. The present state of technological development is illustrated and the inherent limitations of this technique are indicated. The need for more spectral pure sources than those now available and/or different approaches is underlined in connection with the increasing thrust towards the measurement of visible frequencies. View full abstract»

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  • Effect of the worked layer in quartz-crystal plates on their frequency stabilities

    Page(s): 139 - 143
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    Describes the direct measurement of the relation between the worked layers in quartz-crystal plates and their effect on the frequency stability. The rectangular fundamental 5-MHz AT-cut specimen plates lapped and polished with emery powder and cerium oxide, respectively, were placed in gap-type holders and connected with oscillator circuits, and their frequency stabilities were measured. The frequency stabilities are evaluated by the fractional frequency deviation to the nominal frequency ratio, power spectral density, and the Allan variance. The main results are: 1) The frequency drift due to the worked layer is dealt with as a relaxation process. It can be approximated by a sum of one to three terms of an exponential function. 2) The depth of the worked layer has a large effect not only on the long-term frequency stability but on the medium term in the Fourier frequency range of 10-3 to 10-7 Hz. 3) It does not have a dominant effect on the short-term stability with an averaging time of less than 10 s. View full abstract»

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  • Single shunt fault diagnosis in a resistive ladder

    Page(s): 143 - 146
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    The problem of locating a single shunt fault in a uniform resistive ladder network is considered. A simple method, based on resistance measurements is proposed for the case where the total number of nodes is small and all of them are accessible. Two strategies are discussed for reducing the number of measurements when the number of nodes is large but all nodes are still accessible. When internal nodes are not accessible, it is shown that in theory, it is possible to locate the fault from two resistance measurements at the ports. However, when the number of nodes is large, and the fault is well inside the ladder, such a method is susceptible to large errors. Experimental results are given for some representative ladders. View full abstract»

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  • Analytical and experimental approaches for the design of low-distortion Wien bridge oscillators

    Page(s): 147 - 151
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    Although Wien bridge oscillators are commonly used as fixed-frequency generators of low distortion there has apparently not been suggested a simple systematic method based on nonlinear theory for reducing their distortions. This paper attempts at filling the gap. This is achieved by suggesting a network which is on the one hand a Wien bridge oscillator and it can be also regarded as a Van der Pol oscillator. Van der Pol oscillators, however, are well known and as a result the task of systematically reducing the distortion becomes a straightforward procedure which is demonstrated by a series of experiments. Additional improvements (in the economy of design and with regard to a further reduction of distortions) are attained by slightly modifying the basic Van der Pol type system. The small level of distortion achieved in the present work systems is explained as partly due to the deliberate generation of harmonic components which are then subtracted from the output signal to remove the distortion components which are added by the amplifier circuit. View full abstract»

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  • Network analysis by phase-modulated homodyne detection

    Page(s): 152 - 154
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    The network analyzer method using the homodyne detection principle and a sawtooth or stepped phase modulation can be generalized for an arbitrary phase-modulating function. The adjustment of the phase deviation of the modulated signal yields an exactly linear dependence between the phase of the microwave signal and the phase of the fundamental intermediate frequency signal at the mixer output. View full abstract»

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  • A new 2-kV common-mode voltage wide-band isolation amplifier

    Page(s): 155 - 156
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    Describes a new modulation-demodulation technique for isolation amplifiers, particularly useful for multichannel data acquisition systems. Input and output stages are transformer coupled using an improved version of the amplitude-modulation technique of a symmetric square wave, which requires a simple rectifier bridge for demodulation. Characteristics of the isolation stage obtained in this way are excellent linearity and gain stability, typical of magnetic coupling, and a frequency bandwidth ranging from DC to an upper limit which, at least in principle, is not fixed by the demodulation technique; moreover, common-mode voltages in the kilovolt range are obtainable. Details of an amplifier are given, designed as the analog input stage of a multichannel data acquisition system. View full abstract»

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  • Dynamics of the heterodyne spectrum analyzer with rectangular bandpass filter

    Page(s): 157 - 160
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    A mathematical model of the dynamic frequency characteristics of the heterodyne spectrum analyzer with a rectangular bandpass filter of small relative bandwidth is constructed. The model is investigated numerically and proved experimentally. View full abstract»

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  • An active frequency meter

    Page(s): 160 - 162
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    Deals with the theory and fabrication of a new frequency meter, which is used for the measurement of frequency in the range from a few hertz to 100 kHz. It is a frequency-selective bridge and is made of discrete passive R and C components and an integrated operational amplifier. At bridge balance, the frequency under measurement is given in terms of the values of resistors and capacitors only. Advantages, limitations, and sources of errors of the frequency meter are discussed. The theory is experimentally verified. View full abstract»

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  • A simple technique for precise voltage control of oscillator frequencies

    Page(s): 162 - 165
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    A proportional feedback control scheme is proposed to obtain a precise linear relationship between the control voltage and the frequency of oscillators. Experimental results agree closely with the theory. The scheme is simple in circuitry, versatile, and suitable for mass production. View full abstract»

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  • A decade range linearly tunable versatile filter

    Page(s): 165 - 167
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    A modified version of the Kerwin-Huelsman-Newcomb biquad is presented which is electronically tunable almost linearly over a decade range of center frequency. The circuit is suitable for use as a tunable universal filtering module and can be easily digitally programmed. View full abstract»

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  • A dipole detuning technique for proximity and thickness measurements

    Page(s): 168 - 169
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    Experimental results are presented which demonstrate that both the magnitude and phase of the input reflection coefficient of a dipole placed near a conducting plane are sensitive monotonic functions of the dipole-to-plane separation. Measurement applications which exploit this characteristic are suggested. View full abstract»

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  • Contributors

    Page(s): 169 - 173
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  • [Advertisements]

    Page(s): 174 - 175
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  • [Advertisements]

    Page(s): 176
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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
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