Showing papers in "IEEE Transactions on Instrumentation and Measurement in 1972"
TL;DR: In this article, an analysis of an arbitrary 6-port junction, four ports of which are terminated by power meters, shows that the net power input (or output) at either of the remaining ports is a linear function of the four power meter indications.
Abstract: An analysis of an arbitrary 6-port junction, four ports of which are terminated by power meters, shows that the net power input (or output) at either of the remaining ports is a linear function of the four power meter indications. The validity of this result has been experimentally demonstrated at 10 GHz. This device promises to be a useful tool in a wide variety of power measurement and calibration problems.
204 citations
TL;DR: In this article, a six-port coupler is described with four side arms whose outputs are proportional to the voltage, current, incident voltage wave, and reflected voltage wave at some desired measurement plane in the transmission line.
Abstract: A six-port coupler is described having four side arms whose outputs are proportional to the voltage, current, incident voltage wave, and reflected voltage wave at some desired measurement plane in the transmission line. The phase relationship between the outputs is the same as between corresponding quantities at the measurement plane. Complex impedance and phase angle as well as voltage, current, and power can be obtained from simple power or voltage magnitude measurements at the four side arms. A vector voltmeter used with this six-port becomes a direct reading vector impedance meter, admittance meter, or reflection coefficient meter.
148 citations
TL;DR: In this paper, a time-domain (transient) method for measurement of the dielectric properties of biological substances is described and theoretical analysis of the time dependence of the reflection coefficient following application of a step voltage to a shunt capacitor located at the end of a transmission line and filled with a very small amount of the Dielectric showing the Debye dispersion is given.
Abstract: A time-domain (transient) method for (broad-band) measurement of the dielectric properties of biological substances is described. Theoretical analysis of the time dependence of the reflection coefficient following application of a step voltage to a shunt capacitor located at the end of a transmission line and filled with a very small amount of the dielectric showing the Debye dispersion is given. Analysis and calculations of the overall uncertainty of permittivity measurements as well as experimental results are presented and limitations of the method discussed.
53 citations
TL;DR: In this paper, a new concept for compensating for sensitivity changes of a differential transformer due to variations in temperature and excitation conditions is described, which is based on utilization of the individual outputs from the secondary coils, not only as a differential output but also as a reference output.
Abstract: This paper describes a new concept for compensating for sensitivity changes of a differential transformer due to variations in temperature and excitation conditions. The idea is based on utilization of the individual outputs from the secondary coils, not only as a differential output but also as a reference output. The differential transformer usually has two secondary coils connected in opposition to obtain a differential output. If the voltages induced in the individual secondary coils e1 and e2 are individually taken out and if the operation (e1 - e2)/(e1 + e2), is carried out, then the result becomes independent of temperature and excitation conditions. The experiments, which were made to confirm the effectiveness of this method, gave quite impressive and hopeful results: superior temperature, excitation independence and linearity.
47 citations
TL;DR: In this paper, the design and performance of two high-accuracy transformers, identified as amplifier-aided two-stage transformers (A2T) are described.
Abstract: The design and performance of two high-accuracy transformers, identified as amplifier-aided two-stage transformers, are described. Each operates from 50 Hz to 10 kHz, supporting burdens up to 1 ?. Self-contained ratios span from 5/5 to 100/5, with a rated secondary current of 5 A. Results indicate the errors at 10 kHz are within 30 and 15 ppm for the respective transformers, decreasing to less than 1 ppm at 1 kHz. Analysis of high-and low-frequency errors is presented, as well as a detailed description of a capacitance trimming technique effecting a factor-of-ten reduction of capacitive errors. Also described is a relatively simple step-up calibration system for determining the transformer errors. Calibration results are included.
47 citations
TL;DR: In this paper, the authors examined the influence of both Thomson heating and the reactive components of the heater on the performance of the NPL multijunction convertor, and set out the theoretical analysis that supports the claim that its ac/dc transfer difference does not exceed 1 or 2 ppm up to a frequency of 100 kHz.
Abstract: Measurements of the rms values of alternating currents are frequently made by means of thermal transfer instruments. At low and midfrequencies Thomson heating can have an important influence on the ac/dc transfer difference of these devices, whereas at higher frequencies the variation with frequency of the effective resistance of their heaters is the most decisive factor. The present paper examines the influence of both Thomson heating and the reactive components of the heater on the performance of the NPL multijunction convertor, and sets out the theoretical analysis that supports the claim that its ac/dc transfer difference does not exceed 1 or 2 ppm up to a frequency of 100 kHz.
46 citations
TL;DR: In this article, a calorimeter is described that can measure megajoules of laser energy from CW lasers whose output wavelength is in the region from 1 to 11?m. The calibration of this device is traceable to NBS electrical standards.
Abstract: A calorimeter is described that can measure megajoules of laser energy from CW lasers whose output wavelength is in the region from 1 to 11 ?m. The calibration of this device is traceable to NBS electrical standards. This calorimeter can measure total energies from 3 × 104 to 107 J. The laser power range this device can handle ranges from 300 to 100 000 W.
33 citations
TL;DR: In this paper, the magnetic field gradients produced by a current sequentially activating a few turns of wire of a precision solenoid are used to measure its pitch, and the position of the activated portion of wire can be resolved to 0.1?m.
Abstract: The magnetic-field gradients produced by a current sequentially activating a few turns of wire of a precision solenoid are used to measure its pitch. The position of the activated portion of wire can be resolved to 0.1 ?m. Preliminary results are found to be in agreement with an earlier measurement using a contacting probe to within the uncertainty of the latter determination. This new technique reduces many of the difficulties associated with conventional pitch measuring schemes and at the same time provides a method of obtaining increased accuracy.
31 citations
TL;DR: The NPL calculable cross capacitor as mentioned in this paper was designed to provide a standard of the highest accuracy, and it has a vertical axis and the length is determined by central guard tubes.
Abstract: The NPL calculable cross capacitor is designed to provide a standard of the highest accuracy. It has a vertical axis and the length is determined by central guard tubes. The length is altered by axial displacement of the lower tube and the change is measured interferometrically. This paper describes the construction and performance of the capacitor and records the results of the initial measurements; the uncertainty of these is of the order of 10-7.
30 citations
TL;DR: In this paper, the three-voltmeter method is used for power calculation with 0.01 percent error at frequencies below 5 kHz and a unique test procedure is described for the comparison of the threevoltmeter device and a time-division multiplier wattmeter operating at zero power factor.
Abstract: The accuracy and frequency response limitations in the present square-law responding laboratory wattmeters have promoted the search for alternate methods of ac power measurement using electronic instrumentation. The three-voltmeter method is based on an old principle of operation implemented by new analog circuitry. Results of the tests reported here show a precision of power calculation with 0.01 percent error at frequencies below 5 kHz. A unique test procedure is described for the comparison of the three-voltmeter device and a time-division multiplier wattmeter operating at zero power factor.
27 citations
TL;DR: In this article, a simple method for the calculation of errors due to the finite length and separation of X-array hot-wire anemometers is described, which does not require complete correlation or spectral functions of the flow and includes the effect of nonuniform wire sensitivity.
Abstract: This paper describes a simple method for the calculation of errors due to the finite length and separation of X-array hot-wire anemometers. Results of computations for a typical wire array are presented for total and spectral turbulence measurements. Although the actual errors are slightly underestimated due to the simplifying assumptions used to reduce the computational effort, it is found that the wire length and separation effect is very significant. The analysis does not require complete correlation or spectral functions of the flow and includes the effect of nonuniform wire sensitivity.
TL;DR: The independent atomic time scale at the National Bureau of Standards AT(NBS) is based upon an ensemble of continuously operating cesium clocks calibrated occasionally by an NBS primary frequency standard.
Abstract: The independent atomic time scale at the National Bureau of Standards AT(NBS), is based upon an ensemble of continuously operating cesium clocks calibrated occasionally by an NBS primary frequency standard. The data of frequency calibrations and interclock comparisons are statistically processed to provide nearly optimum time stability and frequency accuracy. The long-term random fluctuation of AT(NBS) due to nondeterministic perturbations is estimated to be a few parts in 1014, and the present accuracy is inferred to be 1 part in 1012. A small coordinate rate is added to the rate of AT(NBS) to generate UTC(NBS): this small addition is for the purpose of maintaining synchronization within a few microseconds of other international timing centers. UTC(NBS) is readily operationally available over a large part of the world via WWV, WWVH, WWVB, and telephone; also via some passive time transfer systems, eg., Loran-C and the TV line-10 system; and also experimentally via satellite and WWVL. The precision and accuracy of these dissemination systems will be discussed.
TL;DR: In this article, the authors describe a complete prototype system that uses an open-ended microwave cavity for making dynamic density measurements of flowing hydrogen in a transfer line, and test results for both the single and two-phase cases are presented and discussed.
Abstract: The density measurement of liquid hydrogen and two-phase mixtures of liquid and gaseous hydrogen is considered. This paper describes a complete prototype system that uses an open-ended microwave cavity for making dynamic density measurements of flowing hydrogen in a transfer line. The theory of operation along with test results for both the single- and two-phase cases are presented and discussed.
TL;DR: Using an optically pumped atomic beam resonator, a redetermination of the hyperfine structure separation of the ground state of 87Rb has been made as discussed by the authors, where the zero-field value is 6 834 682 612.8 ± 0.5 Hz.
Abstract: Using an optically pumped atomic beam resonator a redetermination of the hyperfine structure separation of the ground state of 87Rb has been made. The zero-field value ??0 = 6 834 682 612.8 ± 0.5 Hz agrees with previous determinations made with conventional atomic beams.
TL;DR: In this article, a probe using thin-film techniques to construct an array of extremely lossy dipoles makes possible an electromagnetic radiation monitor, having a 3dB bandwidth from 300 MHz to 18 GHz, isotropic response, and independence of polarization.
Abstract: A probe using thin-film techniques to construct an array of extremely lossy dipoles makes possible an electromagnetic radiation monitor, having a 3-dB bandwidth from 300 MHz to 18 GHz, isotropic response, and independence of polarization. The measurement range is from 20 ?W/cm2 to 20 mW/cm2.
TL;DR: In this paper, the cavity-pulling factor of passive frequency standards is derived for all values of the gain of the atomic medium and gives, in particular, the cavity pulling factor when the oscillation threshold is approached.
Abstract: Assuming a Lorentzian shape for the atomic line, we calculate the cavity-pulling factors of passive frequency standards, taking into account the modification of the applied electromagnetic field by the atomic radiation. The calculation is therefore valid for all values of the gain of the atomic medium and gives, in particular, the cavity-pulling factor when the oscillation threshold is approached. The effect of saturation of the line by the field is included. Two expressions of the cavity-pulling factor are derived. One applies when the electromagnetic field level in the cavity is measured, and the other when the population of the atomic levels is analyzed. Consequences of these results are discussed. An experimental verification of the theoretical results is given, when the resonance of the field level in a hydrogen maser cavity is monitored in conditions where the oscillation threshold is approached.
TL;DR: In this paper, the cylindrical skin effect response on 50-air dielectric lines is compared with the planar skin effect in terms of the time-domain error introduced by the skin effect approximation.
Abstract: The time-domain error introduced by the planar skin-effect approximation is examined by comparing the approximate response with the cylindrical skin-effect response. Expressions are developed for the cylindrical skin-effect response and applied to line outer conductor ID sizes ranging from a 0.1-mm microminiature size to 10 mm. For 50-air dielectric lines (including 3.5 and 7 mm) curves are given for the cylindrical skin-effect response transition (rise) time (0 to 50 percent and 10 to 90 percent) versus line length (0.01-100 m). Step responses are given for a 1-m length of 0.1-mm 50-? microminiature line with relative dielectric constants of 1, 2, and 3.
TL;DR: In this paper, a method for evaluating the conductivity and permittivity spectrum of materials by using time-domain reflectometry is presented, with emphasis on the asymptotic behavior for large values of time.
Abstract: A method is presented for evaluating the conductivity and permittivity spectrum of materials by using time-domain reflectometry. A theoretical analysis of the transient response is made, with emphasis on the asymptotic behavior for large values of time. The results of the asymptotic analysis are the basis of the presented method and are essential for the evaluation of the permittivity spectrum of conductive materials. Quite satisfactory experinental results are presented.
TL;DR: The history of atomic and molecular frequency control can be traced from the earliest molecular beam magnetic resonance experiments in 1938 through the present as mentioned in this paper, and the history of frequency control has been studied in detail.
Abstract: The history of atomic and molecular frequency control will be traced from the earliest molecular beam magnetic resonance experiments in 1938 through the present.
TL;DR: Outputs of a Gray code counter are used to synthesize digital Walsh functions that are free from hazards and also uses a binary code to select the order.
Abstract: Outputs of a Gray code counter are used to synthesize digital Walsh functions that are free from hazards. This method, which produces sequency-ordered Walsh functions, also uses a binary code to select the order.
TL;DR: In this article, the current status of time-domain metrology in material and distributed network research is described and the causes and magnitude of system errors are discussed along with continuing work to improve system performance.
Abstract: The current status of time-domain metrology (TDM) in material and distributed network research is described. After a brief summary of earlier work, the operation and features of two prototype material measurement units are discussed. These semiautomated systems utilize a 5-V step recovery diode pulse generator and computer-controlled scanning procedures incorporating time-window stabilization and variable-dwell-time averaging. The larger, 10-ns time-window unit measures the complex permittivity and permeability over a frequency range of 0.1-10 GHz in about 10 min. The causes and magnitude of system errors are discussed along with continuing work to improve system performance. In distributed network research, the capabilities of TDM for calibration are being determined. From measured signal-to-noise ratios, it was calculated that random noise contributes less than 1 percent error for insertion loss measurements up to 50 dB over the frequency range 0.4-8 GHz. Other topics discussed include: identification and evaluation of error sources, pulse generator development, measurement configurations and procedures, and testing of waveguide and ferrite components.
TL;DR: In this paper, the desired measurement accuracy, the relationship between field intensity, absorbed power, and hazards, and the usefulness of E and H field intensity measurements are discussed, and a block diagram and the basic parameters of a universal measuring instrument now under development are included.
Abstract: The desired measurement accuracy; the relationships between field intensity, absorbed power, and hazards; and the usefulness of E and H field intensity measurements are discussed. Measurement accuracy versus the dimensions of the E-field antenna; measurement accuracy versus the capacitive coupling of the antenna with its surroundings; and measurement accuracy versus instrument calibration accuracy are all considered. A block diagram and the basic parameters of a universal measuring instrument now under development are included.
TL;DR: In this paper, a generalized equation is derived that represents relations between properties of a device under test and an indication of a measuring instrument having signal generators and an input port, which can be applied to most narrow-band radiometers or reflection-measuring instruments.
Abstract: A generalized equation is derived that represents relations between properties of a device under test and an indication of a measuring instrument having signal generators and an input port. The equation can be applied to most narrow-band radiometers or reflection-measuring instruments. Considering only factors measured outside the instrument, the equation permits exact measurements of properties of the device under test or easier evaluation of errors in the measurements without any consideration of structures or inner properties of the instrument. In addition, according to this concept, a new method permitting direct measurements of mismatch factors or delivered powers and a possibility of a radiometer to be used for reflection measurements are suggested.
TL;DR: In this paper, a new method for an absolute measurement of voltage is given, based on the phenomenon that, when one electrode of a capacitor supplied with a constant voltage is moved, the amount of the change of the electrostatic energy stored in the capacitor is equal to the work required for this movement.
Abstract: A new method for an absolute measurement of voltage is given. It is based on the phenomenon that, when one electrode of a capacitor supplied with a constant voltage is moved, the amount of the change of the electrostatic energy stored in the capacitor is equal to the work required for this movement. A prototype of an apparatus to be used in this method was prepared and its performance has been examined. In an ideal case, it is considered possible to determine the voltage with an accuracy of a few parts in a million with this apparatus.
TL;DR: In this paper, the theory of dielectric absorption is discussed and a compensation circuit is suggested to reduce the effect of absorbent materials in analog memories and electronic integrators, based on measurements on capacitors with paper, cellulose acetate, parylene, polyester, polycarbonate, and polystyrene dielectrics.
Abstract: Experience from experiments with a sample and hold circuit showed that dielectric absorption constitutes a fundamental limitation of the accuracy in analog memories. To gain more insight into the problem several materials commonly used as dielectrics in capacitors have been investigated. The theory of dielectric absorption is discussed. Results from measurements on capacitors with paper, cellulose acetate, parylene, polyester, polycarbonate, and polystyrene dielectrics are reported. The components in Dow's model, which describes the dielectric absorption, are calculated for the polycarbonate dielectric. A compensation circuit is suggested, which considerably reduces the effect of dielectric absorption in analog memories and electronic integrators.
TL;DR: In this paper, a new approach to the digital measurement of angular velocity is presented, which performs the division by time that has been carefully avoided in the existing instruments, leading to up to 14700 samples per second.
Abstract: A new approach to the digital measurement of angular velocity is presented. This new instrument performs the division by time that has been carefully avoided in the existing instruments. The accuracy and resolution of the transducer does not depend upon the number of quantizations/revolution. The measurements can be made in a very short time, leading to up to 14700 samples per second. An important feature of this instrument is that even at speeds close to zero (or at zero), the error is less than 0.02 percent and 1600 samples of the angular velocity can be obtained/second. This makes the instrument particularly suitable for the study and control of the transient behavior of motors and other rotating devices.
TL;DR: In this article, it was found that when converted to a common unit of voltage, most measured values of 2e/h agreed with each other to within the 1 to 2 parts in 107 estimated uncertainty of the volt comparisons.
Abstract: Using temperature-regulated transportable standard-cell enclosures, the National Bureau of Standards (NBS), under the auspices of the Bureau International des Poids et Mesures (BIPM), during the period June 1971 through June 1972 has carried out a series of direct comparisons of the units of voltage as-maintained by NBS and BIPM, Sevres, France; the National Physical Laboratory, United Kingdom; the National Research Council, Canada; the National Standards Laboratory, Australia; and the Physikalisch-Technische Bundesanstalt, Germany. The main purpose of these comparisons was to provide a sound basis for intercomparing values of 2e/h obtained at the various national laboratories via the ac Josephson effect in superconductors. It was found that when converted to a common unit of voltage, most measured values of 2e/h agreed with each other to within the 1 to 2 parts in 107 estimated uncertainty (1 standard deviation) of the volt comparisons. This satisfying result would seem to indicate that serious consideration should be given to adopting a single international value of 2e/h for use in maintaining units of voltage.
TL;DR: In this article, it was shown that thin dielectric films on the electrodes of certain types of cylindrical cross capacitors tend only to produce equal and opposite contributions to the phase angles of the two cross capacitances.
Abstract: It has been found that under proper conditions thin dielectric films on the electrodes of certain types of cylindrical cross capacitors tend only to produce equal and opposite contributions to the phase angles of the two cross capacitances. To a lesser degree, this same type of cancellation effect has been found to be associated with toroidal cross capacitors.
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TL;DR: The International Atomic Time (IAT) is a mean of local independent atomic time scales as discussed by the authors and the current procedure uses an algorithm ensuring the long-term stability, with fixed weights roughly proportional to the number of operating cesium standards.
Abstract: The International Atomic Time (IAT) is a mean of local independent atomic time scales. The current procedure uses an algorithm ensuring the long-term stability, with fixed weights roughly proportional to the number of operating cesium standards. We found that the scale unit of IAT varied by probably less than 2 × 10-13 in relative value between January 1970 and December 1971. We tested some methods of weighting: they did not bring any substantial improvement. Our work suggests a more promising approach and also a means of maintaining both stability and accuracy.
TL;DR: In this paper, a microwave system for attenuation measurement by means of the modulated subcarrier method supplying additional information on the actual parameters of the system is described, which can be used for automatic control of output signal indicator sensitivity making the results independent of the instability of these parameters.
Abstract: In this paper a microwave system for attenuation measurement by means of the modulated subcarrier method supplying additional information on the actual parameters of the system is described. The information can be used for automatic control of output signal indicator sensitivity making the results independent of the instability of these parameters. Experimental results are reported illustrating the validity of the analysis.