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Instrumentation and Measurement, IEEE Transactions on

Issue 4 • Date Aug 1989

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Displaying Results 1 - 17 of 17
  • Wide frequency range sine wave VCO with a tunable inductor and capacitor

    Publication Year: 1989 , Page(s): 876 - 881
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (412 KB)  

    A voltage-controlled oscillator (VCO) with sine wave output has been built using a tunable inductor along with a tunable capacitor to operate at frequencies ranging from 100 kHz to over 20 MHz. The method of tuning the inductor by changing the permeability of its ferrite core and the ability to extend the frequency response of the core are discussed. Dynamic characteristics of the VCO are explained with examples of a parallel and series tank implementation View full abstract»

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  • Windows and interpolation algorithms to improve electrical measurement accuracy

    Publication Year: 1989 , Page(s): 856 - 863
    Cited by:  Papers (162)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (528 KB)  

    An FFT-based measurement technique, which can be easily used to determine accurately the frequency, amplitude, and phase of all the harmonic and interharmonic components of a distorted signal, is examined. Suitable windows and interpolation algorithms are examined in order to reduce undesirable effects due to spectral leakage caused by a sampling process that is not synchronized. Several results concerning the application of different windows on a set of simulated signals are compared to verify the capability of the proposed procedure. The influence of the noise is examined to study the filtering properties of the weighting functions View full abstract»

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  • A state variable approach to designing a resistive input, low noise, noninverting differentiator

    Publication Year: 1989 , Page(s): 920 - 922
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (352 KB)  

    A state variable approach to designing a resistive input noninverting differentiator is presented. The differentiator consists of an active integrator and a summer. The upper break frequency where differentiation ceases is tunable by trimming a single resistance. The lower corner frequency where differentiation starts is tunable by varying the RC product of an integrator. The differentiation of high-frequency noise is avoided by switching to amplifier action at high frequencies. The integrator de-emphasizes high-frequency noise View full abstract»

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  • A resonator impedance de-embedding procedure

    Publication Year: 1989 , Page(s): 864 - 869
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (352 KB)  

    In many contemporary high-frequency circuits, a dielectric resonator is coupled to a microstrip line section, the ends of which constitute a two-port. A detailed procedure is presented for recovery of impedance values associated with the resonator from S-parameter measurements on the two-port with a vector network analyzer. The procedure is suitable for computer-assisted numerical processing, takes into account lossy propagation and moderate impedance vagaries along the microstrip line, and includes discontinuities in the coax-to-microstrip transitions. Resonant frequency, unloaded Q, and effective coupling coefficient can be determined subsequently from the de-embedded impedance values View full abstract»

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  • Report on international comparison of power at 94 GHz

    Publication Year: 1989 , Page(s): 927 - 929
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (188 KB)  

    An international comparison of power standards at 94 GHz was approved at the 1983 meeting of the Radio Frequency Working Group of the Consultative Committee on Electricity, Participants in the comparison were ETL (the pilot laboratory, Japan), LCIE (France), NIST (US), and RSRE(UK). Three thermistor mounts as the transfer standards were circulated among the participants, who measured the effective efficiencies of the mounts. Relative deviations in power measurements at 94 GHz by the participants lie within a range of 1.3% View full abstract»

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  • A novel direct reading active-RC system for measurements of in-circuit, discrete, and incremental capacitances

    Publication Year: 1989 , Page(s): 922 - 925
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (428 KB)  

    A simple, low-component active-RC circuit is given for the measurement of in-circuit, discrete, and incremental capacitances. The measurement circuit provides the measured value of capacitance directly in terms of the circuit's output voltage. The proposed system provides good accuracy for these measurements. The capacitance measurements are independent of the signal frequency. Experimental results that support the theory are included View full abstract»

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  • Progress in VLBIS at Shanghai Observatory

    Publication Year: 1989 , Page(s): 929 - 931
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (160 KB)  

    An overview is presented of recent developments on very-long-baseline interferometry (VLBI) at the Shanghai Observatory. The Shanghai Radio Station, which is equipped with a 25-m antenna, and other facilities that became operational in 1988, are described. The VLBI data-processing system is discussed. It includes an S-2 VLBI data processor and a series of postcorrelation processing programs for astronomy as well as geodesy. There are now two VLBI groups in Shanghai Observatory working on astronomy and geodynamics, and some current research is outlined View full abstract»

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  • Uncertainties in the determination of dielectric properties in the infinite sample method

    Publication Year: 1989 , Page(s): 902 - 906
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (356 KB)  

    In the infinite-sample method, the sample permittivity is found from the measured input reflection coefficient. The reflection coefficient domain of a traveling-wave system is transformed into the complex permittivity domain by two subsequent mappings which include the inverse bilinear and Schwarz-Christoffel transformations. The error bounds in permittivity measurements are derived. The dielectric properties and respective uncertainties are presented for a water sample in the form of the Cole-Cole diagram. The case presented represents the first step leading to a more general presentation of uncertainties in dielectric measurements View full abstract»

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  • A programmable active-R sine wave oscillator with microprocessor control

    Publication Year: 1989 , Page(s): 925 - 927
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (188 KB)  

    The design and analysis of a simple active-R oscillator based on a two-pole operational amplifier model are described. The oscillator is tunable by one resistor over a fairly wide range at low sensitivities. A digitally programmable oscillator was derived by replacing the tuner resistor with an array of switched binary weighted resistors. The CMOS switches were activated and controlled by a SDA-UNI-01 microcomputer system based on the 8085 microprocessor. The performance of the programmable oscillator and its extension as a switched frequency-shift-keyed wave generator were verified View full abstract»

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  • Instrumentation for time-resolved measurement of ultrasound velocity deviation

    Publication Year: 1989 , Page(s): 913 - 916
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (280 KB)  

    An inexpensive digital data acquisition unit is described which has the capability to record ultrasound velocity variations up to 20 m/s in ultrasound velocity at rates up to 1000 readings per second. No calibration procedures are required. The intrinsic velocity resolution of the unit is less than 1 part in 106; however, the short-term frequency instability of the phase-locked loop instrument used as a velocity sensor limits the overall resolution to 1 part in 10 5 View full abstract»

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  • Analysis of the performance of the capacitive displacement transducer

    Publication Year: 1989 , Page(s): 870 - 875
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (392 KB)  

    An output signal from the capacitive displacement transducer has been mathematically modeled. Interest is focused on the importance of the spectral content of the signal in determining transducer performance. It has been shown that the phase-error due to the space harmonics of the capacitance between the receiving and transmitting electrodes always exhibits a ripple with the spatial frequency equal to the number of the transmitting electrodes. An analysis of the mathematical model suggests general rules of mechanical and electrical design that are necessary in order to create effective and viable devices with reduced measurement errors. In particular, a variety of the staircase functions with rapidly decreasing Fourier components can be applied as the driving supply. Another alternative is to combine a specially formed driving supply with low-pass filtering in the time domain. Experimental results for three different (four-, six-, and eight-phase) transducer systems confirm the validity of the model View full abstract»

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  • Development of a microprocessor interface to a scanning electron microscope

    Publication Year: 1989 , Page(s): 907 - 912
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (500 KB)  

    The development and applications of a microprocessor interface to a scanning electron microscope (SEM) for SEM image acquisition and electron-beam writing is described. The design considerations and system-related constraints along with necessary modifications to the SEM are presented. Hardware and software optimization is attempted, and the approach is discussed. Some results of applications are presented View full abstract»

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  • Effect of various dither forms on quantization errors of ideal A/D converters

    Publication Year: 1989 , Page(s): 850 - 855
    Cited by:  Papers (29)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (332 KB)  

    The quantization error of a quantizer (ideal A/D converter) is investigated. Correlation between quantization error and quantizer input is considered. The input signal is taken as a sinusoid due to its importance in instrumentation systems. The cases of no dither, uniform dither, and discrete (digital) dither are considered. Effects of the dither probability density function (PDF) are discussed. The relationship between uniform dithered and discrete dithered quantizer inputs is derived. Spectra of the average quantization error, corresponding to an arbitrary input signal, are investigated. Different dither forms (Gaussian, uniform, and discrete) are compared, and the effects of the dither PDF are discussed. A quantitative basis for comparing dither forms, and hence, selecting the one most appropriate for a particular application, is provided View full abstract»

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  • Repetitive waveform high frequency, high precision digitizer

    Publication Year: 1989 , Page(s): 917 - 920
    Cited by:  Papers (18)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (252 KB)  

    A digitizing technique for measuring high-speed phenomena with very high precision is described. A commercially available waveform digitizer using this method is shown to exhibit settling times of less than 5 ns to 0.1% and less than 10 ns to 0.01% after a voltage transition. Also, RMS measurements of sine waves up to 100 MHz show errors on the order of that obtained using a thermal transfer standard View full abstract»

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  • Calibrating network analyzers with imperfect test ports

    Publication Year: 1989 , Page(s): 898 - 901
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (308 KB)  

    The test ports on automatic network analyzers are generally built with an impedance that matches the impedance of the calibration standards. Experimental evidence is presented that substantial impedance discontinuities can be tolerated at the test port interface if proper calibration procedures are observed. The 50-Ω test port on one of the six-ports in a dual six-port network analyzer was replaced with a 75-Ω test port. This test port was then calibrated to look like a 50-Ω test port. Measurements on various devices show that it is possible to make a 75-Ω test port indistinguishable from a 50-Ω test port View full abstract»

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  • Spline function approximation for velocimeter Doppler frequency measurement

    Publication Year: 1989 , Page(s): 892 - 897
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (400 KB)  

    A spline function approximation approach for measuring the Doppler spectral peak frequency in a laser Doppler velocimeter system is presented. The processor is designed for signal bursts with mean Doppler shift frequencies up to 100 MHz, input turbulence up to 20%, and photon counts as low as 300. The frequency-domain processor uses a bank of digital bandpass filters for the capture of the energy spectrum of each signal burst. The average values of the filter output energies, as a function of normalized frequency, are modeled as deterministic spline functions which are linearly weighted to evaluate the spectral peak location associated with the Doppler shift. The weighting coefficients are chosen to minimize the mean square error. Performance evaluation by simulation yields average errors in estimating mean Doppler frequencies within 0.5% for poor signal-to-noise conditions associated with a low photon count of 300 photons/burst View full abstract»

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  • An inference monitor with real-time FFT spectral analysis for a radio observator

    Publication Year: 1989 , Page(s): 882 - 891
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (896 KB)  

    A system is described which uses a real-time fast Fourier transform (FFT) spectrum analyzer to monitor radio interference near 408 MHzs occurring at a radio observatory. Direction of arrival, frequency, intensity, and time of occurrence are recorded under the control of a microcomputer. A sensitive receiver can be connected to any one of eight directional antennas to establish direction of arrival. The receiver output is digitized to 8 b, and analyzed by the FFT spectrum analyzer which has a real-time bandwidth of 0.5 MHz. A total bandwidth of 20 MHz is analyzed in segments of 0.4 MHz. The analyzer uses the modified periodogram method developed by P.D. Welch (IEEE Trans. Audio Electroacoust., vol.AU-15, p.70-3, June 1967), and a Kaiser-Bessel windowing function is applied to ensure low sidelobes. Dynamic range is 40 dB, and the interference monitor obtains high sensitivity to very weak interfering signals by time averaging. Several general design principles which arise out of certain constraints are elucidated. Some new results are presented concerning the detectability of small signals by FFT processors 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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Dipartimento di Elettrotecnica
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alessandro.ferrero@polimi.it
Phone: 39-02-2399-3751
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