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Instrumentation and Measurement, IEEE Transactions on

Issue 2 • Date June 1988

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Displaying Results 1 - 25 of 35
  • Comments, with reply, on "Minimization of reactive power under nonsinusoidal conditions" by L.S. Czarnecki

    Publication Year: 1988 , Page(s): 328 - 330
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (280 KB)  

    The commenter argues that ignoring compensator rating in the optimal design of a shunt LC compensator for power engineering applications is neither realistic nor physically justified. Furthermore, minimization of source reactive power only with respect to either L or C results in a not necessarily global minimum. Computation and var specification errors were also found and corrected. For comparison purposes, a realistic optimal design procedure is presented. In replying, Czarnecki states that compensators of reactive power are built in order to minimize an additional cost caused by the presence of reactive power in the circuit, and at their optimization the capital cost of the compensator must be taken into account. When the load parameters do not change, the compensator designer does not need any algorithm for reactive power minimization, but only a method to minimize the overall cost, since just this minimum is the criterion for the compensator optimization. However, when the reactive power of the load varies over a broad range, the designer may conclude that the cost minimization requires an adaptable compensator. He discusses two problems that have to be solved when its parameters are being adapted to the load.<> View full abstract»

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  • Calculation of confidence intervals for high-voltage impulse reconstruction

    Publication Year: 1988 , Page(s): 201 - 206
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (472 KB)  

    An algorithm designed to calculate confidence intervals for solutions to ill-posed problems subject to unequality constraints is applied to the calculation of confidence intervals for a high-voltage impulse distorted by a divider system. Applications of the method to measurements made with resistive and capacitive dividers illustrate its value for obtaining useful stochastic error bounds for high-voltage impulse restoration. The technique can be useful for sensors with a directly measurable unit step response. For other dividers its utility has been adequately demonstrated View full abstract»

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  • Measurement of satellite communication parameters: satellite antenna measurements

    Publication Year: 1988 , Page(s): 285 - 291
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (500 KB)  

    The in-orbit testing of a communication satellite involves the measurements of key communication parameters, which determine communication subsystem behavior and verify the design. Some of the tests, specifically those involving the satellite's antennas, are unique in that they require satellite antenna motion in both azimuth and elevation. They can only be conducted in the postlaunch period prior to the operational phase of the satellite. The focus is on the antenna tests, in order to verify antenna pattern design and put a bound on satellite antenna crosspolarization isolation, or lack of it, by comparing in-orbit test results with computer predictions and range measurements. Measurement procedures and instrumentation for the in orbit measurement of satellite antenna parameters are considered. The measurement procedures are reflected in equations in which the unknown parameter is expressed by measurable or calculatable quantities. The measurement error is evaluated on the basis of the parameter equation and component error estimates View full abstract»

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  • Automatic material characterization at microwave frequencies

    Publication Year: 1988 , Page(s): 280 - 284
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (344 KB)  

    An instrument was assembled to measure complex permittivity at microwave frequencies in an efficient, inexpensive manner. It bridges the gap between traditional, tedious methods of characterization and expensive vector network analyzer techniques. A microcomputer is used to control the operation of a scalar network analyzer. Measurements of the magnitude of the reflection and transmission coefficients are automatically made as a function of frequency and temperature over a range of 2-18 GHz. A theory is developed covering the different regimes of operation: the thin sample, the multiple reflecting sample, and the high insertion loss sample. Sample thickness criteria for accurate measurements are reported. Results are presented for dielectric and semiconductor samples View full abstract»

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  • Electromagnetic techniques for measurements on coal combustors

    Publication Year: 1988 , Page(s): 309 - 314
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (344 KB)  

    A microwave interferometric technique for measuring the density in the free-board space of a fluid bed combustor is described. A method for measuring the unburnt coal content in the ashes of a coal combustor is proposed. In the first case, the density measurement is obtained by evaluating the phase shift of an electromagnetic wave which propagated through the space under test. In the second case, the unburnt coal content is obtained by processing the reflection coefficient measured at the input section of a suitable holder for the ashes. The experimental results obtained for both measuring methods show the validity of the methods View full abstract»

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  • On the implementation of an analog ATPG: the nonlinear case

    Publication Year: 1988 , Page(s): 252 - 258
    Cited by:  Papers (17)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (460 KB)  

    In order to reduce the complexity of the fault diagnosis equations and still retain computational simplicity, a self-testing algorithm has been proposed and implemented on a VMS VAX 11/780 for linear circuits. A prototype implementation of such an algorithm for nonlinear circuits and systems is presented. The proposed analog automatic test program generator (AATPG) for nonlinear circuits and systems is divided into offline and online processes. Unlike the simulation of the pseudocircuits in the linear case, which can be achieved by a matrix/vector multiplication, the circuit simulator SPICE is used to simulate the nonlinear pseudocircuits. The automatic SPICE code generator required for this simulation is presented. The proposed AATPG for nonlinear circuits has been implemented on a VMS VAX 11/780. The actual test can be run in either a fully automatic mode or interactively View full abstract»

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  • Radome design and measurements

    Publication Year: 1988 , Page(s): 292 - 295
    Cited by:  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (188 KB)  

    Radome performance (transmission loss and boresight error) is evaluated by means of a computer code the input data of which are the geometry (radome shape, layered structure configuration, and antenna/radome relative position) and the antenna aperture magnetic current distribution. The latter is measured directly, thus avoiding the difficulty of characterizing the antenna under test. The spherical near field (SNF) measuring technique is applied. A radome has been designed using this approach and then manufactured and tested by means of a compact range. The comparison between experimental and theoretical results is quite good View full abstract»

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  • Determination of short-term error caused by the reference clock in precision time-interval measurement and generation

    Publication Year: 1988 , Page(s): 315 - 316
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (160 KB)  

    A simple analysis based on the randomized clock cycle T 0 yields a useful formula on its variance in terms of the Allan variance. The short-term uncertainty of the measured or generated time interval t is expressed by the standard deviation in an approximate form as a function of the Allan variance. The estimates obtained are useful for determining the measurement uncertainty of time intervals within the approximate range of 10 ms-100 s View full abstract»

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  • Peak factor minimization of input and output signals of linear systems

    Publication Year: 1988 , Page(s): 207 - 212
    Cited by:  Papers (27)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (496 KB)  

    An overview is given of existing analytical and numerical methods for the comparison of the peaks of discrete, finite sum of sines. A novel method that compresses the signals optimally or almost optimally is presented. The algorithm is extended to the simultaneous compression of the input and output signals of a linear system. The implications of strong signal compression for the signal-to-noise ratio lead to the formulation of a two-step optimal experimental setup for system identification and parameter estimation of linear systems View full abstract»

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  • Digital spectra of nonuniformly sampled signals: fundamentals and high-speed waveform digitizers

    Publication Year: 1988 , Page(s): 245 - 251
    Cited by:  Papers (127)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (536 KB)  

    A digital spectral representation of a nonuniformly sampled signal is derived, and a spectrum analysis of a nonuniformly sampled sinusoid is presented. It is found that the spectrum of a nonuniformly sampled sinusoid comprises uniformly spaced line spectra; in addition, the signal-to-noise ratio is obtained in closed form. The theories are then applied to analyze the harmonic distortion introduced in high-speed waveform digitizers due to time-base errors. Specifically, waveform digitizers are analyzed which utilize interleaving/multiplexing and random equivalent time-sampling techniques and the monolithic A/D converter technology to extend their capabilities. Theoretical results are confirmed by experimental results with a real waveform digitizer View full abstract»

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  • Determination of optical constants of solids by an automatic reflectometer

    Publication Year: 1988 , Page(s): 296 - 299
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (348 KB)  

    An absolute reflectance spectrometer was designed. The instrument is based on an Apple II microcomputer which automates data acquisition, curve fitting, Kramers-Kronig integration, and data plotting. In this system, both the positions of the sample and the detectors are fixed during measurement. The reference and sample signals are detected by scanning a mirror which is engaged with a precise stepping motor. The computer controls all the peripheral instruments; therefore the need of continuous attention to the gain control, frequency scanning, and mirror adjustment is eliminated. Versatile software allows the collected data to be easily manipulated and analyzed View full abstract»

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  • Fast generation of a white and normal random signal

    Publication Year: 1988 , Page(s): 316 - 318
    Cited by:  Papers (1)  |  Patents (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (244 KB)  

    A novel weighting function for a digital filter is proposed for generating a white and normal random signal from a binary signal. The weighting function is derived from an even-shift orthogonal sequence. A filter with this weighting function can generate a white and normal random signal very quickly View full abstract»

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  • A simple envelope detector

    Publication Year: 1988 , Page(s): 223 - 226
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (948 KB)  

    The use of integration and differentiation as Hilbert transformers for envelope detection is considered. The resulting detectors are causal and do not require exact knowledge of carrier phase or frequency. The method requires square and square root operations, but no multiplication. An upper bound is established for magnitude error View full abstract»

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  • Frequency of a methane-stabilized helium-neon laser

    Publication Year: 1988 , Page(s): 179 - 184
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (512 KB)  

    A phase-locked laser frequency chain was used to measure the absolute frequency of a HeNe/CH4 laser relative to the primary Cs standard, with measurement uncertainty less than ±1 part in 1012. The frequency depends on laser parameters; a spread of 8.3×10-11 was observed. This was attributed to the variation of Lamb dip asymmetry resulting from the gas-lens effect and the accompanying diffraction loss variation near resonance. Means of improving laser frequency reproducibility by reducing cavity diffraction loss variation were studied experimentally. The frequency obtained with a cavity exhibiting the smallest Lamb dip asymmetry was found to be 88 376 181 599.07±0.07 kHz View full abstract»

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  • Digitally programmable active-C OTA-based oscillator

    Publication Year: 1988 , Page(s): 320 - 322
    Cited by:  Papers (1)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (236 KB)  

    An active-C OTA-based oscillator circuit is introduced. The circuit features noninteractive electronic tunability, uses the minimum number of active and passive components, and has low sensitivity characteristics. The frequency of oscillation can be digitally controlled and the circuit can be easily interfaced with mini/microcomputer-based or microprocessor-based systems View full abstract»

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  • A digital hygrometer

    Publication Year: 1988 , Page(s): 300 - 304
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (500 KB)  

    A digital hygrometer using a polyimide capacitive humidity sensor is developed. The capacitance change of the sensor due to adsorption of water vapor in the atmosphere is detected by a switched-capacitor digital capacitance bridge controlled by a one-chip microcomputer and is displayed as relative humidity with 0.1% resolution. The accuracy of the hygrometer calibrated by a two-point method is solely determined by the temperature dependence and the long-term drift of the dielectric sensitivity of the sensor and is estimated to be 2% View full abstract»

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  • A new cavity configuration for cesium beam primary frequency standards

    Publication Year: 1988 , Page(s): 185 - 190
    Cited by:  Papers (23)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (460 KB)  

    In the design of cesium beam frequency standards, the presence of distributed cavity phase shifts (associated with residual running waves) in the microwave cavity, due to the small losses in the cavity walls, can become a significant source of error. To minimize such errors in future standards, it has been proposed that the long Ramsey excitation structure be terminated with ring-shaped cavities in place of the conventional shorted waveguide. The ring cavity will minimize distributed cavity phase variations at the position of the atomic beam, provides only that the two sides of the ring and the T-junction feeding the ring are symmetric. A model is developed to investigate the validity of this concept in the presence of the small asymmetries that inevitably accompany the fabrication of such a cavity. The model, partially verified by laboratory tests, predicts that normal tolerances will allow the frequency shifts due to distributed cavity phase variations to be held at the 10-15 level for a beam tube with a Q of 108 View full abstract»

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  • An error estimate for quasi-integer-period sampling and an approach for improving its accuracy

    Publication Year: 1988 , Page(s): 219 - 222
    Cited by:  Papers (20)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (304 KB)  

    The problem of error reduction is studied. Both synchronous and asynchronous samplings are considered, and a method is proposed for describing the error in the frequency domain. Its advantages are that the input signal does not need to be restricted to the band-limited hypothesis, and that a comparison of the various processing methods can be conveniently made. A compensation method for improving accuracy is discussed View full abstract»

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  • Adapter correction in the measurement of two-port devices

    Publication Year: 1988 , Page(s): 323 - 325
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (252 KB)  

    After an automatic network analyzer has been calibrated at its primary connectors, the full scattering matrices of adapters can be found with two known reflection standards in the secondary connector system. In coaxial systems, the standards can advantageously be a matched load and two `half standards'-a short for phase and an open circuit for magnitude. The method is applicable to noninsertable devices, waveguides, and novel transmission lines View full abstract»

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  • A digital frequency synthesizer-phase sensitive detector

    Publication Year: 1988 , Page(s): 318 - 320
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (392 KB)  

    A digital-frequency-synthesizer-phase-sensitive-detector based on a Texas Instruments TMS32010 digital signal processor has been designed and constructed. It can be operated as a standalone instrument as well as under remote control from a desk-top computer through an IEEE 488 (GPIB) interface. The frequency, gain, bias, and attenuation of the instrument are programmable. A 24-character 5×7 dot-matrix alphanumeric display system and 16 digit keyboard are used to display the results for the inphase and quadrature signals, and to change the programmable constants. The instrument is intended for use as a low-frequency network analyzer View full abstract»

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  • A programmable self-adaptive digital frequency multiplier

    Publication Year: 1988 , Page(s): 227 - 230
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (336 KB)  

    Existing self-adaptive frequency multipliers work well if the master clock frequency is an integral multiple of the input signal frequency; otherwise they lose an output pulse after a certain interval of time. The frequency of this missing pulse could be as high as half of the input frequency. Since existing self-adaptive frequency multipliers are not programmable, the multiplication factor can not be changed without doing some major changes in the hardware. The reason for missing an output pulse is explained, and design and implementation of a programmable self-adaptive digital frequency multiplier, that does not have this missing pulse problem are presented. The errors associated with the multiplier are discussed View full abstract»

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  • De-embedding two-port noise parameters using a noise wave model

    Publication Year: 1988 , Page(s): 195 - 200
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (396 KB)  

    Equations are presented, suitable for computer or calculator, for accurately de-embedding the noise parameters of both the first and the second two-port in a cascade of noisy two-parts from known values of the noise parameters of the cascade. The derivations are presented in terms of a noise wave model for two-ports, using transfer scattering small signal parameters. A numerical example is presented in which the noise parameters of two cascaded passive two-ports having unequal physical temperatures are individually de-embedded from the noise parameters of the cascade. As a check on the analysis presented, the noise parameters of each two-port are also calculated directly from its scattering parameters and physical temperature View full abstract»

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  • General formulas for calculating magnetic field at a receiving loop placed at an arbitrary position from a radiating loop in a shielded room

    Publication Year: 1988 , Page(s): 268 - 273
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (336 KB)  

    The standard magnetic field radiated by a small loop antenna is used for sensitivity testing of radio receivers. To avoid interference from external sources, the test is often carried out in a shielded room. A formula to obtain the intensity of the magnetic field at the receiving loop, when a small radiating loop antenna and the receiving loop antenna are placed at random locations in a shielded room, is derived. The convergence of the formula is analyzed. Using the formula, an equation is derived which expresses the shielded room error or the effect of the room on the standard magnetic field. The correlations between the calculated values of the error and the measured results are reported View full abstract»

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  • An efficient algorithm to compute Allan variance from spectral density

    Publication Year: 1988 , Page(s): 240 - 244
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (300 KB)  

    An efficient algorithm is presented for conversion of spectral density, the measure of signal purity commonly used in the design process, to another popular measure, Allan variance. Curves are presented that show the relationship between parameters controlling the degree of approximation and the resulting inaccuracy. A flow chart of the algorithm is given. Execution times for a sample problem are compared with times using simpler algorithms View full abstract»

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  • The geometric mean of power (amplitude) spectra has a much smaller bias than the classical arithmetic (RMS) averaging

    Publication Year: 1988 , Page(s): 213 - 218
    Cited by:  Papers (17)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (384 KB)  

    The statistical properties of the geometric mean of power (amplitude) spectra resulting from a discrete Fourier transform (DFT) are compared with those of arithmetic (RMS) averaging. The statistical properties are verified by means of frequency-domain and time-domain simulations. It is shown that the asymptotic bias of the geometric mean is a function of the fourth-order moments of the measurement noise 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
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