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Instrumentation and Measurement, IEEE Transactions on

Issue 4 • Date Dec. 1988

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Displaying Results 1 - 25 of 38
  • Electronic compensation of voltage transformers

    Page(s): 652 - 654
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (210 KB)  

    A method for compensating ratio errors and phase displacements of measuring voltage transformers by a simple electronic circuit is introduced. This electronic compensator keeps the primary winding isolated from the secondary winding, so that it can be applied to voltage transformers in any kind of use. It also works with large load power variations. With this compensation, smaller and cheaper transformers may fulfil the same accuracy and power output requirements as larger transformers.<> View full abstract»

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  • Accurate digital control and rotation of the phase of microwave signals

    Page(s): 626 - 630
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    A method of remotely controlling the phase and phase rates of low-frequency reference signals using digital techniques is described. These signals can, in turn, be used to control the phase of a microwave local oscillator in a phase array. The system, which was designed to control the phase of the local oscillators in a radio astronomy array called the Australian Telescope, gives phase resolution of 0.18° and phase rates up to 2×104 rad/s View full abstract»

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  • A digitally programmable temperature controller based on a phase-locked loop

    Page(s): 582 - 585
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    A digitally programmable temperature controller is developed based on a phase-locked loop. Temperature under control is converted to frequency form and then compared, in a phase detector, with the reference frequency which corresponds to the target temperature. The detected phase drives the actuator. The frequency difference is also detected by a one-chip microcomputer which changes the reference frequency according to a proportional-integral-derivative operation. A prototype controller achieved 0.1° C stability in the temperature control of a water bath. It is concluded that the principles of control are compatible with intelligent sensors now being developed and are applicable to the control of other quantities, such as humidity, pressure, and flow View full abstract»

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  • Technique for measuring the dielectric constant of thin materials

    Page(s): 631 - 636
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (392 KB)  

    A practical technique for measuring the dielectric constant of vegetation leaves and similarly thin materials is presented. A rectangular section of the leaf is placed in the transverse plane in rectangular waveguide, and the magnitude and phase of the reflection coefficient are measured over the desired frequency band using a vector network analyzer. By treating the leaf as an infinitesimally thin resistive sheet, an explicit expression for its dielectric constant is obtained in terms of the reflection coefficient. Because of the thin-sheet approximation, however, this approach is valid only at frequencies below 1.5 GHz. To extend the technique to higher frequencies, higher-order approximations are derived and their accuracies are compared to the exact dielectric-slab solution. For a material whose thickness is 0.5 mm or less, the proposed technique was found to provide accurate values of its dielectric constant up to frequencies of 12 GHz or higher View full abstract»

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  • Voice technology in the instrumentation of the automobile

    Page(s): 586 - 590
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (416 KB)  

    The author discusses the applications of voice technology in modern automobiles. A major goal of this technology is to add artificial intelligence to the instruments of the vehicle to improve the safety and reliability of the vehicle. Two aspects of speech technology are discussed, namely, speech synthesis and speech recognition. Speech synthesis is mainly used to generate verbal warning messages whenever a problem is detected in the vehicle. In addition, verbal messages can be generated to advise the driver to perform certain tasks to improve the performance of the automobile. In the second application of voice technology, namely, speech recognition, the basic goal is to create hands-free control of some of the automobile functions, taking direction from the driver's voice View full abstract»

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  • A variable temperature test station for extraction of semiconductor device modeling parameters

    Page(s): 610 - 614
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    The authors describe the equipment and software necessary to integrate a variable-temperature setup and an automated data-collection system to extract semiconductor device modeling parameters over a wide temperature range. A cryogenic test station with a temperature range of 1.8-300 K is used for semiconductor device evaluation, with the test structure mounted in an 8-pin, TO-99-style header. The system consists of a custom low-temperature apparatus and state-of-the-art electrical instrumentation under control of a minicomputer. An electromagnet suitable for Hall studies with a custom-designed 1.1-kW programmable power supply for automated control of the magnetic field completes the system. The cryogenic test station has been used to study the characteristics of n-channel Hall-effect MOSFETs from 1.8 K to room temperature View full abstract»

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  • Deep level transient spectroscopy: instrumentation induced anomalous characteristics

    Page(s): 596 - 599
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    The authors attempted to clarify, compare, and contrast some previously unpublished difficulties encountered in the operation of deep-level transient spectroscopy (DLTS) systems, and describe corrective measures where applicable, including instrumentation and deep level anomalies which may affect capture cross section designations, such as pulse squaring and degeneracy factor effects. Thermal lag between sample and sensor has been demonstrated to cause the apparent peak temperatures of deep levels to be in error by several degrees. In addition, analysis of deep level data from a single ΔC-vs.-T plot has been achieved from half-peak-height points of the graph, for use where no other data are available from the sample under test. Trap depth determination from a single thermal scan of fragile Schottky barriers was considered View full abstract»

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  • Measuring harmonic distortion and noise floor of an A/D converter using spectral averaging

    Page(s): 525 - 528
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    The author proposes to use spectral averaging techniques to measure the harmonic distortion and noise floor of an analog/digital (A/D) digitizing subsystem. The noise floor of an ideal B-bit A/D converter is derived in closed form. It is shown that this noise floor is a function of the A/D resolution B, the record length N, and the equivalent noise bandwidth EB of the window function used in the discrete-Fourier-transform (DFT) computation. For an example, the noise floor is given for the case in which the magnitude square of the spectrum is averaged. Both experimental and simulation results are presented and it is shown that they are in good agreement with the theoretical results View full abstract»

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  • Monitoring permanent-magnet motor heating with phosphor thermometry

    Page(s): 637 - 641
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    The fiber-optic-conveyed, laser-induced fluorescence of a thermographic phosphor was used to measure the surface temperature of the rotor in an operating permanent-magnet motor. The technique uses a pulsed laser to interrogate a surface-bonded film of europium-doped lanthanum oxysulfide for the purpose of determining its temperature-dependent, exponential-decay lifetime. By using digital-delay circuitry to control the measurement systems timing, the authors achieved spatial resolutions of better than 2 mm at speeds of up to 700 rotations/s. The precision of the temperature measurements was 0.3°C. The details of the measurement system are presented and discussed View full abstract»

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  • A 1/fγ power spectrum noise sequence generator

    Page(s): 615 - 619
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    The authors discuss the design of a noise sequence generator that provides a stationary process that follows a 1/fγ law over a limited frequency band. The kind of noise is generated by passing a white-noise sequence in a digital filter characterized by a frequency-response-squared module proportional to 1/fγ. The design of the digital filter is performed in a straightforward manner by applying the matched z-transform to the transfer function of a proper analog filter. The digitalization error is also discussed, and a simple and useful design method for a flicker-like noise generator with exponents γ between -2 and 2 is reported. It is shown that the Barnes-Jarvis 1/f noise generator can easily be derived as a particular case with γ=1 View full abstract»

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  • A power system digital harmonic analyzer

    Page(s): 537 - 540
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    The authors describe the design of a harmonic analyzer for use in studying the harmonic content of commercial electric power. This MC 68000-based instrument samples the waveform and calculates the first 63 harmonics of the 60-Hz fundamental for both a voltage and current waveform. The 64-kbyte memory is adequate for one week of hourly samples for a power-quality survey by an electrical utility. The analyzer is quickly attached to the outputs of potential and current transformers by alligator clips and a current plug. The harmonic data are retrieved from the instrument by a portable computer. A separate personal computer (PC) program is then used for data analysis. Accuracy is shown to be about 0.1%, more than adequate for power quality surveys View full abstract»

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  • A recent nationwide comparison of single mode optical fiber attenuation measurements

    Page(s): 655 - 656
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (164 KB)  

    An interlaboratory measurement comparison was conducted by the Shanghai Institute of Testing Technology in China. Four single-mode fibers, having lengths of 6, 2, 2, and 1.6 km, were used. Measurements of attenuation at 1.3 μm and 1.55 μm gave one standard-derivation spread of 0.01, 0.02, 0.03, and 0.02 dB/km at 1.3 μm and 0.01, 0.09, 0.06, and 0.05 dB/km at 1.55 μm View full abstract»

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  • Frequency switching speed measurements using a delay line discriminator

    Page(s): 620 - 625
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (388 KB)  

    Frequency switching speed (FSS) measurements around 3 GHz are presented, using a delay line discriminator (DLD). A relation is derived that governs the quasistatic condition for the transfer function of the DLD. Under the quasistatic condition, the transformation of the DLD output signal to the transient frequency of the input signal requires only harmonic functions in the mathematical transformations. An expression is derived for the signal-to-noise ratio of the measurement circuit's output signal, with examples relating to analog and digital oscilloscopes as recording devices. It is concluded that the DLD is a powerful and economical tool for FSS measurements View full abstract»

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  • Determination of DC motor transients using a microcomputer

    Page(s): 600 - 604
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (332 KB)  

    A method is presented to determine DC motor transients using an 8085-based microcomputer. The scheme was tested in the laboratory and results verified. The step response and the back electromotive force (EMF) constant have been determined for a small permanent-magnet DC micromotor. The results have been cross-checked with those obtained from a storage oscilloscope and the specifications of the manufacturer to a good accuracy. The authors describe the principle of transconduction, the counter programming, the monitoring of the back EMF of the motor, and the program organization View full abstract»

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  • Sinewave parameter estimation algorithm with application to waveform digitizer effective bits measurement

    Page(s): 529 - 532
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (288 KB)  

    The authors present a high-performance (i.e. high-precision and high-speed) algorithm to estimate the four parameters of a sine wave from a sampled data record. The estimation errors are derived in closed form, and hence, controllable. The authors then propose a method to measure a digitizers effective bits based on this algorithm. Simulation results indicate that the proposed method gives excellent estimates of the true resolution of the simulated ideal digitizer. This proposed algorithm is noniterative and gives swift and consistent results View full abstract»

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  • Ultrasonic void estimation system for determination of liquids in microgravity tanks

    Page(s): 642 - 647
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    An ultrasonic measurement technique has been developed for determining the quantity of liquid storage tanks in the microgravity environment. When the void fraction in a vessel is sufficiently small and the liquid wets the vessel, a spherical void interior to the liquid forms. The proposed procedure, the void estimate center technique (VECT), uses an iterative algorithm to compute the center location and thus the radius of a spherically shaped void. The VECT algorithm has been developed as a two-dimensional model that can also be easily extended to three-dimensional problems. After evaluating different transducer locations, a prototype was constructed and its performance was evaluated. Both system design and hardware are discussed in detail View full abstract»

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  • Logtone crest factors

    Page(s): 656 - 657
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    The Schroeder and random methods are compared with a time-frequency-domain swapping algorithm for the crest-factor reduction of logtones used in 1/3 octave analysis. The theoretically stated tendency of logtone-crest factors to grow with the square root of the logarithm of the number of components is confirmed experimentally. This dependence also holds for optimally compressed logtones View full abstract»

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  • Measurement of launching efficiency into multimode optical fibers using semiconductor laser diodes

    Page(s): 561 - 563
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    A detailed and systematic study has been carried out of the launching efficiency of light, from semiconductor laser diodes into graded-index multimode optical fiber waveguides. Four different terminations of the fibers were investigated: plane-ends, hemispherical ends, taper-with-hemisphere ends, and roof-top (RT) ends. Besides launching efficiency, the parameters of interest were the various misalignments, such as axial, lateral, and angular, between laser and fiber, and the effect of these to produce a reduction in the launching efficiency. It is shown that RT fibers increase the launching efficiency considerably but rotational optimization of the fiber about its axis is essential. It is noted that this is a considerable disadvantage as most of the other techniques considered do not require the optimization View full abstract»

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  • A high speed data acquisition and analysis system for ultrasonic energy measurements

    Page(s): 515 - 518
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (348 KB)  

    A high-speed microcomputer-based data acquisition and analysis system was designed and constructed. The system was interfaced to an ultrasound sector scanner. The primary application of the system, in this case, was to measure the power spectrum of the backscattered (low-level) ultrasound signal from acoustic inhomogeneous media, such as liver tissue. The system was bench-tested and then tested successfully in normal operative conditions. The system digitizes the ultrasound signal, with sample rate of 16 Msample/s and stores the digitized data in a temporary storage (static random-access memory). When the temporary storage is full, the data is transferred to a microcomputer, where a fast Fourier transform algorithm is applied to calculate the power spectrum of the ultrasound signal. Pattern-recognition algorithms are applied to differentiate between normal and abnormal liver tissues using the acoustic attenuation coefficient as the differentiation feature View full abstract»

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  • Impact of digital signal processing on measurement and test instruments

    Page(s): 519 - 524
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (428 KB)  

    The authors discuss the impact of digital signal processing on test instruments and describe the use of a single-chip digital signal processor called TriStar whose architecture has been tailored for the instrumentation environment. TriStar instructions and programming are described, and attention is given to typical applications of TriStar, including averaging, fast Fourier transform, and interpolations. The authors explain how the processor delivers high throughput for these applications View full abstract»

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  • A drift-compensating precision divider technique using circular data patterns

    Page(s): 533 - 536
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (316 KB)  

    A divider is described which is able to provide precision integer-to-one ratios (or those ratios nearby). The technique for using the divider compensates for most of the drift associated with resistive dividers. Data acquisition and reduction are based on flexible circular data patterns. An application of the divider is described where it is used to establish the relationship between 10-V solid-state standards and 1.018-V saturated standard cells. Comments are included on the repeatability and accuracy obtained with the divider View full abstract»

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  • Damping of compression and shear piezoelectric accelerometers by electromechanical feedback

    Page(s): 572 - 577
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    It is shown that the very pronounced resonance peak in the frequency entirely by a simple modification of existing accelerometers, providing them with an electrical sensor output as well as an electrical actuator input, and using a charge amplifier in a feedback path between the sensor output and the actuator input. Because a piezoelectric accelerometer is normally read out by a charge amplifier, no extra circuitry (expense) is necessary to provide this electromechanical feedback. It is shown that a maximally flat response (Butterworth) can be obtained with little peaking (approximately 2 dB) and excellent dynamic stability, which makes the acceleration usable up to its resonance frequency View full abstract»

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  • CALIBRAT: a software for control and calibration of electronic measurement devices

    Page(s): 497 - 500
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    CALIBRAT is a software package designed to facilitate quality assurance plan implementation, particularly in the French military establishment. CALIBRAT is intended to be used for a quality assurance plan for measurement devices (mainly multimeters). It includes a high-level language for writing control and calibration procedures and a result database for analysis. Complementary tools like operator dialog, specialized editor, and help for the constitution of a devices library, makes its use very easy and versatile. The set of powerful tools has been developed with specific IEEE-488 bus command oriented keywords and an instrument manager to provide independence between the language and the instruments. CALIBRAT can be run on a personal computer with a GPIB-PC1 or -PC2 National Instruments Board IEEE-488 bus controller View full abstract»

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  • GPIB and the battle of incompatible languages

    Page(s): 488 - 492
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    The author outlines what the IEEE 488.1 and 488.2 standards cover with regard to operating language, what specifications are available, and detailed instructions on how to design a language which facilitates user tolerance. Various features of language design are considered, including mnemonics, minimum uniqueness, the command table, the required characters table, the offset table, and search routines. The problem of the conflict between so-called GPIB (general-purpose interface bus)-compatible instruments, which in fact are compatible, is addressed. It is concluded that, as the instrument specific language standards that are available are not universally accepted or applied, the use of an English-like language is one of the best ways to avoid compatibility problems View full abstract»

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  • Single-mode fiber measurements

    Page(s): 557 - 560
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    The author discusses the various techniques used to characterize the following transmission parameters of single-mode fibers: attenuation, cutoff wavelength, mode-field diameter, and chromatic dispersion. The cutback method, the insertion-loss method, and optical time-domain reflectometry are considered for attenuation measurements. The single-band and power step methods are considered for cutoff-wavelength measurements. The transverse-offset, and near- and far-field techniques are considered for the measurement of mode-field diameter, and time- and frequency-domain methods and interferometry are considered for chromatic-dispersion measurements. The single-bend and power step methods are considered for cutoff-wavelength measurements 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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Editor-in-Chief
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Dipartimento di Elettrotecnica
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Phone: 39-02-2399-3751
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