Showing papers in "IEEE Transactions on Instrumentation and Measurement in 1983"
TL;DR: In this paper, a new scheme is presented for the determination of the parameters that characterize a multifrequency signal, where the signal is weighted before the discrete Fourier transform (DFT) is calculated from which the frequencies and complex amplitudes of the various components of the signal are obtained by interpolation.
Abstract: A new scheme is presented for the determination of the parameters that characterize a multifrequency signal. The essential innovation is that the signal is weighted before the discrete Fourier transform (DFT) is calculated from which the frequencies and complex amplitudes of the various components of the signal are obtained by interpolation. It is shown that by using the Hanning window for tapering substantial improvements are achieved in the following respects: i) more accurate results are obtained for interpolated frequencies, etc., ii) harmonic interference is much less troublesome even if many tones with comparable strengths are present in the spectrum, iii) nonperiodic signals can be handled without an a priori knowledge of the tone frequencies. The stability of the new method with respect to noise and arithmetic roundoff errors is carefully examined.
440 citations
TL;DR: In this paper, a calibration method for network analyzer calibration in measurements of the dielectric properties of materials using an open-ended coaxial line probe is proposed to alleviate this limitation.
Abstract: Routine network analyzer calibration procedures in measurements of the dielectric properties of materials using an open-ended coaxial line probe are frequently inadequate and limit the accuracy of measurements. A calibration method, which makes use of liquids whose properties are well known, is proposed to alleviate this limitation. It is shown that even one liquid used as a standard in place of a matched load greatly improves the accuracy of measurements. Theoretical relationships and experimental results as well as some practical suggestions related to the application of this method are given.
167 citations
TL;DR: In this paper, a method for deconvolving a jitter-related effective impulse response from the recorded waveform data was proposed to reduce the distortion caused by the jitter between the trigger signal and the sampling strobe.
Abstract: The presence of time jitter between the trigger signal and the sampling strobe in an equivalent-time sampling oscilloscope can cause appreciable distortion of the recorded waveform. Under additive signal averaging conditions, a method has been developed to reduce this distortion. The method consists essentially of deconvolving a jitter-related effective impulse response from the recorded waveform data.
109 citations
TL;DR: In this paper, four waveform recorder tests are presented that characterize dynamic performance using sine-wave sources, and in some cases indicate the specific errors limiting performance. But, they do not consider the performance of a single source.
Abstract: Four waveform recorder tests are presented that characterize dynamic performance using sine-wave sources. Each test illuminates different aspects of dynamic performance, and in some cases indicate the specific errors limiting performance. Pitfalls in using the tests are also examined.
81 citations
TL;DR: This paper is concerned with the theoretical principles, description, operation, and performance of a down-conversion system based on the subharmonic sampling technique intended for use on microwave oscillators with good frequency-stability performance.
Abstract: The use of digital techniques for the precise measurement of medium- and short-term frequency stability of oscillators requires good resolution of the frequency counter. In the case of microwave oscillators, this is often preceded by some form of down-conversion. This paper is concerned with the theoretical principles, description, operation, and performance of a down-conversion system based on the subharmonic sampling technique. The system is intended for use on microwave oscillators with good frequency-stability performance and has as main features the use of a single frequency-stable reference oscillator and a pulse generator-sampler which allows power optimization of the subharmonic selected. The complete experimental system is presented and the limitations are discussed.
67 citations
TL;DR: In this article, an optimization criterion for the selection of the iteration parameter for the frequency-domain optimal compensation deconvolution is presented, which is designed to minimize the decon-volution result's noise content while maintaining its accuracy.
Abstract: An optimization criterion for the selection of the iteration parameter for the frequency-domain optimal compensation deconvolution is presented. The criterion is designed to minimize the deconvolution result's noise content while maintaining its accuracy. Examples are presented to verify the criterion as well as to demonstrate its application.
56 citations
TL;DR: In this paper, a system for calibrating active/reactive power and energy meters under sinusoidal conditions using a current comparator bridge is described, which can be made at any power factor from zero lag through unity to zero lead, positive or negative power at 100 to 120 V, 1 to 5 A, and 50 or 60 Hz.
Abstract: A system for calibrating active/reactive power and energy meters under sinusoidal conditions using a current comparator bridge is described. Measurement can be made at any power factor from zero lag through unity to zero lead, positive or negative power, at 100 to 120 V, 1 to 5 A, and 50 or 60 Hz. The system features a digital oscillator, a thermal rms ac/dc voltage comparator, an automatically compensated capacitor for producing an accurate and stable reactive component, and a microcomputer for control and data reduction. The systematic uncertainty of the calibration system is estimated to be not more than 15 parts per million (ppm).
50 citations
TL;DR: In this article, a potentiometer with the extremely small relative uncertainty of a few parts in 109 has been developed by utilizing the property that a Josephson junction generates a precise voltage that is variable with frequency and step number.
Abstract: A potentiometer with the extremely small relative uncertainty of a few parts in 109 has been developed by utilizing the property that a Josephson junction generates a precise voltage that is variable with frequency and step number. The evaluated total uncertainty is 2.5 × 10-9V for measurements at the 1-V level. This small uncertainty is attributed to the generation of a higher than normal Josephson voltage, that is, on the order of 100 mV.
50 citations
TL;DR: In this article, an equivalent circuit of an open-ended coaxial line used as a sensor for dielectric measurements is proposed, and the parameters of the circuit are found by least square fitting to the values for the total capacitance calculated numerically.
Abstract: An equivalent circuit of an open-ended coaxial line used as a sensor for dielectric measurements is proposed. The parameters of the circuit are found by least square fitting to the values for the total capacitance calculated numerically.
44 citations
TL;DR: In this paper, the output voltages of a ratio transformer are defined at open-circuit coaxial connectors, and a special socket and a difference transformer are used to construct a voltage comparator accurate to 1 in 1010.
Abstract: The output voltages of a ratio transformer are defined at open-circuit coaxial connectors. A special socket and a difference transformer, wound with coaxial cable, are used to construct a voltage comparator accurate to 1 in 1010. Subdivided transformers are calibrated by comparing the voltage difference between taps with that of an isolated winding on the same transformer. Two similar transformers are compared directly using two voltage comparators.
44 citations
TL;DR: In this article, an open-ended coaxial line and a computer-controlled network analyzer have been extensively used for measuring the tissue permittivity in vivo at radio and microwave frequencies.
Abstract: An open-ended coaxial line and a computer-controlled network analyzer have been extensively used for measuring the tissue permittivity in vivo at radio and microwave frequencies. An analysis is presented of measurement errors resulting from calibration and random errors of the network analyzer [1],[2]. The uncertainties in our system are ?? = 0.05 dB and ?? = 0.3°. Key Words-Radio frequency, Microwave permittivity in vivo, Automated network analyzer.
TL;DR: In this paper, a high-precision automatic digital ac bridge including a digital detector as an integral part of the bridge is presented, and an automatic method to reduce the errors caused by the differential nonlinearity is described.
Abstract: This paper deals with a high-precision automatic digital ac bridge including a digital detector as an integral part of the bridge. The resolution and systematic errors of this type of bridge are formulated. An automatic method to reduce the errors caused by the differential nonlinearity is described.
TL;DR: In this paper, the surface accuracy of a large millimeter-wavelength antenna was measured at 86.1 GHz to an accuracy of 4?m at the surface using an interferometric approach.
Abstract: An instrument has been built which allows the electromagnetic measurement of the surface accuracy of a large millimeter-wavelength antenna. The University of Texas 4.9-m radio telescope has been measured with this technique at 86.1 GHz to an accuracy of 4 ?m at the surface. Our technique is an interferometric one which is fast, accurate, and able to measure the whole antenna surface at once. While the technique is illustrated by its use on a large antenna, it could be used in a near-field measurement of a smaller antenna. Several antenna surface maps are presented. A comparison of run-to-run repeatability was made. The technique itself was tested by deforming the antenna surface in a known way and subsequently detecting the deformation.
TL;DR: In this article, the effect of dead time between the data involved in the considered algorithm is pointed out and an experimental analysis is presented which checks the theoretical results for several noise processes in different experimental conditions.
Abstract: The characterization of frequency stability is usually achieved by means of numerically processed time-interval measurements. In the present paper, we study the bias occurring in the frequency stability measure when successive data with the same mean durations are added in order to get different sets of samples with various mean durations. The effect of a dead time between the data involved in the considered algorithm is pointed out. An experimental analysis is presented which checks the theoretical results for several noise processes in different experimental conditions.
TL;DR: In this article, a two-channel time-domain sampler with common time base is used to compare voltages in coaxial lines driven by matched ratio arms from a pulse or sine-wave generator and terminated by unknown and reference admittances.
Abstract: A two-channel time-domain sampler with common time base is used to compare voltages in coaxial lines driven by matched ratio arms from a pulse or sine-wave generator and terminated by unknown and reference admittances. Linear circuit analysis shows that the unknown can be determined from the bridge unbalance sampler outputs by simple calibrations of three frequency-dependent parameters. Design and uses of cells for dielectric measurements and reference terminations are described. Procedures for and results of test measurements are presented for time-domain measurements using a symmetrical power divider as ratio arms and for frequency-domain measurements using a 5O-? power splitter and 5-pF capacitative ratio arms.
TL;DR: In this article, two new methods using the concepts of cross correlation and cross variance are proposed for comparing three oscillators, which allow one to characterize individually each oscillator and reduce the influence of the measurement system noise if the noise sources on each channel are independent.
Abstract: Two new methods using the concepts of cross correlation and cross variance are proposed for comparing three oscillators. They allow one to characterize individually each oscillator and they reduce the influence of the measurement system noise if the noise sources on each channel are independent. Therefore, better resolution can be obtained in the spectral purity and frequency stability measurements.
TL;DR: In this paper, a microcomputer-controlled measurement system for continuous measurement of the density of a streaming liquid is described, which utilizes a transducer that resembles a hollow tuning fork filled with liquid.
Abstract: This paper describes a microcomputer-controlled measurement system for continuous measurement of the density of a streaming liquid. The system utilizes a transducer that resembles a hollow tuning fork filled with liquid. The resonant frequency of the fundamental mode of this device is a function of the liquid density. Piezoelectric means are used to force the device to oscillate and to register the oscillation. A microcomputer controls a frequency sweep, detects the resonant frequency, and converts the frequency to density. Accuracies on the order of 0.05 percent have been recorded in laboratory tests. The system is suitable for industrial applications.
TL;DR: In this article, the capacitance of open-ended coaxial lines is determined experimentally using a resonant technique and an empirical expression for capacitance versus frequency, which enables the open circuit to be used as a calibration standard for microwave network analyzers, is proposed and verified.
Abstract: Capacitance of open-ended coaxial lines is determined experimentally using a resonant technique. An empirical expression for the capacitance versus frequency, which enables the open circuit to be used as a calibration standard for microwave network analyzers, is proposed and verified.
TL;DR: In this paper, the authors describe five different configurations for use with them, namely, a) 0.05-18 GHz parallel 50-kHz substitution system, containing an inductive voltage divider as the reference standard; b) very low drift series 50 kHz substitution system; c) a series substitution system employing coherent detection, which has a dynamic range of 150 dB; d) a 0.18 GHz-voltage ratio system for the automatic calibration of programmable attenuators; e) very stable microwave bridge for the precise measurement of waveguide wall loss.
Abstract: The equipments that have been used in the United Kingdom throughout the last decade for the highest echelon microwave attenuation measurements are approaching obsolescence. To modernize them, two microwave synthesized sources have recently been purchased, and this paper describes five different configurations that have been developed for use with them, namely, a) 0.05-18-GHz parallel 50-kHz substitution system, containing an inductive voltage divider as the reference standard; b) a very low drift series 50-kHz substitution system; c) a series substitution system, employing coherent detection, which has a dynamic range of 150 dB; d) a 0.05-18 GHz-voltage ratio system for the automatic calibration of programmable attenuators; e) a very stable microwave bridge for the precise measurement of waveguide wall loss.
TL;DR: The results of international comparison of methane-stabilized He-Ne lasers at λ = 3.39 μm and IBE-stable He-NE lasers at 633 nm, made by beat frequency techniques, between Bureau International des Poids et Mesures (BIPM) and eleven national laboratories are presented.
Abstract: The results of international comparisons of methane-stabilized He-Ne lasers at λ = 3.39 μm and iodine-stabilized He-Ne lasers at 633 nm, made by beat frequency techniques, between Bureau International des Poids et Mesures (BIPM) and eleven national laboratories are presented. Generally, the measured frequency differences were inside /spl I.chemo/4 × 10-11; but greater frequency differences were observed with some iodine cells (probably as a result of contamination) or when the output power of one laser was two or three times greater than the power of the other laser.
TL;DR: In this paper, it has been found that almost all commercial resistors show anomalous frequency responses at high voltages, and techniques for the selection of the best devices and new resistor mountings are described.
Abstract: Development of new null detectors and the advent of cheap computer power have brought improvements in ac/dc transfer measurements. It has been found that almost all commercial resistors show anomalous frequency responses at high voltages. Techniques for the selection of the best devices and new resistor mountings are described.
TL;DR: In this article, a simple digital capacitance meter which utilizes the RC discharge is proposed and the wide range capability from 0.1 pF to 10 mF and the excellent linearity to ± (0.02 percent of reading + 1 digit) are shown.
Abstract: A simple digital capacitance meter which utilizes the RC discharge is proposed and the wide range capability from 0.1 pF to 10 mF and the excellent linearity to ± (0.02 percent of reading + 1 digit) are shown. The RC discharge capacitance meter provides the capacitance to be measured at a frequency which is reciprocal to the product of the discharge resistance and the measured capacitance. Therefore, the meter can be used to test the frequency dependence of the capacitor even though the test signal is a dc voltage. The proposed RC Discharge Capacitance Meter can also be used in applications such as the measurement of the deviation from the preset value, or the torellance check of capacitance to make the GO or NO-GO decision by adding a few logic gates.
TL;DR: In this article, the structure function of a random process with stationary nth differences is derived from the spectral density of the process, which is used for computing the variance of two estimators of frequency stability.
Abstract: Random processes with stationary nth differences serve as models for oscillator phase noise. The theorem proved here allows one to obtain the structure function (covariances of the nth differences) of such a process in terms of the differences of a single function of one time variable. In turn, this function can easily be obtained from the spectral density of the process. The theorem is used for computing the variance of two estimators of frequency stability.
TL;DR: In this paper, the authors analyze the "equivalent bits" characteristic which is frequently employed as a criterion of the digitizer dynamic performance, and an additional test of the digitization error distribution is proposed.
Abstract: Requirements on measuring accuracy of high-voltage (HV) impulses employed for testing of self-restoring and non-self-restoring insulation are reviewed in order to select a suitable digitizer for the impulse recording. Certain models of fast digitizers are characterized by an apparently high time resolution, but their actual dynamic performance in case of measuring nonrepetitive, irregularly shaped impluses cannot be deduced from the manufacturer specification. The paper analyzes the "equivalent bits" characteristic which is frequently employed as a criterion of the digitizer dynamic performance, and an additional test of the digitization error distribution is proposed. Such a test results in another characteristic of the "equivalent bits," which is based on the maximum (rather than rms) error and which reflects the actual deformation of the recorded impulse form.
TL;DR: In November 1981, a comparison between BIPM and IMGC He-Ne lasers stabilized to saturated absorption lines of 127I2, at the wavelengths ¿ = 633 nm and 612 nm has been made at the B IPM.
Abstract: In November 1981, a comparison between BIPM and IMGC He-Ne lasers stabilized to saturated absorption lines of 127I2, at the wavelengths ? = 633 nm and ? = 612 nm has been made at the BIPM. At 633 nm, a repeatability and a reproducibility within +1 × 10-11 · ? have been obtained. At 612 nm, a repeatability within a few 10-11 · ? only for one laser and a reproducibility of ± 2 × 10-10 · ? have been obtained.
TL;DR: A method is presented for modeling wide-band devices, based on the time-domain reflectometry technique, using computer simulation to improve the modeling accuracy.
Abstract: A method is presented for modeling wide-band devices. The method is based on the time-domain reflectometry technique, using computer simulation to improve the modeling accuracy. Two applications are presented. The first involves modeling of simple line discontinuities to demonstrate the technique as well as to verify its validity. The second application presents the modeling of a multiple discontinuity feedthrough line of a wide-band sampler.
TL;DR: In this article, a digital sinewave generator which spans 1 Hz to 50 kHz is described and the amplitude is characterized by an internal thermal converter and corrected by a microcomputer to an uncertainty of 50 ppm.
Abstract: A digital sinewave generator which spans 1 Hz to 50 kHz is described. The rms amplitude is characterized by an internal thermal converter and corrected by a microcomputer to an uncertainty of 50 ppm. Amplitude is programmable from 0 to 7.07 V rms.
TL;DR: The NBS Reference Flat Pulse Generator (RFPG) as discussed by the authors is used to transfer dc voltage and resistance standards to the nanosecond domain, providing a step amplitude of 1.000 V from a source impedance of 50.0?.
Abstract: The NBS Reference Flat Pulse Generator (RFPG) is used to transfer dc voltage and resistance standards to the nanosecond domain. It provides a step amplitude of 1.000 V (open circuit) from a source impedance of 50.0?. The transition duration is 600 ps, and all perturbations are damped out to less than ±10 mV within 5 ns. It can also be used as a time interval transfer standard.
TL;DR: In this article, the authors describe the design and characteristics of an arbitrary waveform generator, built at the Biophysical and Electronic Engineering Division of the Electrical Engineering Department of the University of Genoa, which exhibits the following features: a) the signal waveform is any band-limited periodic signal, whose frequency content ranges from 0.125 mHz up to 30 MHz.
Abstract: The purpose of this paper is to describe the design and characteristics of an arbitrary waveform generator, built at the Biophysical and Electronic Engineering Division of the Electrical Engineering Department of the University of Genoa, which exhibits the following features: a) The signal waveform is any band-limited periodic signal, whose frequency content ranges from 0.125 mHz up to 30 MHz. The low-frequency limit has been chosen in order to meet the needs of bioengineering, mechanical, and chemical applications. The high-frequency limit covers, for instance, TV and image processing applications. b) The noise level is at least 66 dB below the maximum signal level. c) Typical distortion is less than -66 dB. d) The generator's performance can be easily improved, depending on the availability of up-to-date solid-state devices, without changing its design.