Showing papers in "IEEE Transactions on Instrumentation and Measurement in 1967"
TL;DR: In this paper, a method for precise clocks comparison is described making use of the short rise time of the synchronizing pulse of a current TV picture signal, which can be used to measure simultaneously the time interval between one and the same selected TV frame synchropulse and the pulses derived from the respective clocks.
Abstract: A new method for precise clocks comparison is described making use of the short rise time of the synchronizing pulse of a current TV picture signal. It is shown that by measuring simultaneously the time interval between one and the same selected TV frame synchropulse and the pulses derived from the respective clocks, these clocks may be compared with microsecond accuracy even if widely separated, provided that appropriate correction for the travel time of the synchropulse is applied. An experiment concerning international clock comparison between Prague and Potsdam is described, and the numerical results presented. Synchronization of clocks, separated by about 300 km, to about 2 ?s was accomplished, and it appears that 0.1 ?s is feasible. Further possible applications of this method are discussed.
44 citations
TL;DR: In this article, the authors provide a theoretical base and an error analysis to justify the use of the series-to-parallel transfer technique at low resistance levels using a four-terminal equivalent circuit suggested by Searle.
Abstract: The range and accuracy of resistance calibration can be increased by the use of series and parallel connections of four-terminal resistors. Low value resistors can be permanently connected in series and reconnected in parallel by using Hamon's1 technique to change resistance level without materially affecting resistance accuracy. The resistors are connected in parallel by attaching shorting bars to one terminal at each end of each resistor and attaching matched resistors in series with the other terminals. High accuracy can be attained even though lead and connection resistance are relatively high. The purpose of this paper is to provide a theoretical base and an error analysis to justify the use of the series-to-parallel transfer technique at low resistance levels. The analysis uses a four-terminal equivalent circuit suggested by Searle.2 The accuracy of series and parallel connections of groups of like resistors is investigated in terms of the equivalent circuit. Procedures are developed for determining the connection accuracy of a set of resistors in parallel or series.
29 citations
TL;DR: In this article, a double-calorimeter was developed at the Electrotechnical Laboratory for the measurement of the CW power of the gas laser (He-Ne) with high stability (± 0.05 percent).
Abstract: A new type of microcalorimeter as the laser power standard in Japan has been developed at the Electrotechnical Laboratory. This is a double calorimeter in which the laser power is measured by a dc substitution method using the thermopile unit, and simultaneous measurement is also made using the Peltier cooling-type calorimeter by dc substitution. The CW power of the gas laser (He-Ne) is controlled with high stability (±0.05 percent) by the automatic power control system using the Faraday rotation component. By this method and equipment, the "effective efficiency" of the standard thermopile unit is determined precisely. The errors in this microcalorimetric technique are investigated with the aid of heat flow analysis and auxiliary experiments. As a result, the absolute accuracy of the CW power measurement of laser beams (6328A, 1.15?) is evaluated with high accuracy better than 0.5 percent. The experiments have been successful at 6328A and 1.15 ?, and this method is considered to be available at the region of infrared and far-infrared wavelength.
21 citations
TL;DR: In this paper, a dual-heater thermistors in an automatic double bridge were used to maintain constant temperatures of both thermistors, achieving a linear linearity of 0.02 percent over a four-to-one input range, with response typically 2.5 seconds.
Abstract: A new wideband true rms-to-dc converter is described, covering the ranges of 10 Hz to 100 kHz and 30 mV to 1 kV full scale, with crest factors in excess of 7 to 1. Operation is based on use of two precision dual-heater thermistors in an automatic double bridge, by means of which the temperatures of both thermistors are maintained constant to better than 0.002°C. Converter linearity is 0.02 percent over a four-to-one input range, with response typically 2.5 seconds to settle within 0.1 percent of final value. Applications range from ac signal conditioning for digital voltmeters to 0.01 percent ac-ac transfer work?with nonsinusoidal wave forms as well as the quasi-sinusoids typical in field measurement situations.
20 citations
TL;DR: In this article, a model of the flux leakage pattern within a toroidal transformer is used in conjunction with an analysis of the effect of interwinding capacitances to predict the change of voltage ratio with frequency.
Abstract: The small, but often significant, voltage ratio error of a ratio transformer is caused by leakage of magnetic flux and the flow of displacement currents around the windings A model of the flux leakage pattern within a toroidal transformer is used in conjunction with an analysis of the effect of interwinding capacitances to predict the change of voltage ratio with frequency Reasonably close agreement between this prediction and measured values of voltage ratio suggest that the theory is essentially correct
17 citations
TL;DR: In this paper, an accurate, semiautomatic method of calibrating high-resistance standards is described, where the value of resistance is determined in terms of a fixed threeterminal capacitance, a resistance ratio, and a standard frequency, all being stable and accurately determinable quantities.
Abstract: An accurate, semiautomatic method of calibrating high-resistance standards is described. Measurements of resistances between 109 and 1014 ? at a minimum of 1 V or 10-12 A can be made with an accuracy better than 0.1 percent, each determination requiring typically from 0.5 to 50 s. The value of resistance is determined in terms of a fixed three-terminal capacitance, a resistance ratio, and a standard frequency, all being stable and accurately determinable quantities. The sources of errors and their minimization are discussed; the construction and operation of such a device are described.
17 citations
TL;DR: In this paper, a simple high-sensitivity receiver for simultaneously measuring the amplitude and phase of signals at radio and microwave frequencies is described, for the most part, with standard (microwave) components and employs a modulation technique.
Abstract: A simple high-sensitivity receiver for simultaneously measuring the amplitude and phase of signals at radio and microwave frequencies is described. The receiver is built, for the most part, with standard (microwave) components and employs a modulation technique. The receiver sensitivity, depending on the information bandwidth, is of the order of -100 dBm. Information bandwidths ranging from a few Hz to several MHz are easily achieved.
16 citations
TL;DR: In this article, a new matching procedure was proposed for measuring microwave and millimeter wave power. But the matching procedure is difficult to construct and obtain good performance, as the wavelength gets shorter, and a new unit has been developed which has a very simple structure by virtue of a novel matching procedure.
Abstract: The bolometer unit widely used for measuring microwave and millimeter wave power becomes more difficult to construct and obtain good performance, as the wavelength gets shorter. To overcome these difficulties, a new unit has been developed which has a very simple structure by virtue of a new matching procedure. The bolometer element is made of a thin metal film evaporated on a thin mica substrate, and its mount consists only of a short circuit and a flange. Experimental units have been designed at 35 GHz and 10 GHz, and these have demonstrated excellent characteristics, such as high efficiency, low VSWR, wide bandwidth, high power handing capacity, etc. The thermistor units applying the same matching theory are also investigated at 35 GHz and 50 GHz.
16 citations
TL;DR: This principle leads to a zero-crossing detector (detector II) which is relatively insensitive to system gain fluctuations, and an application of the zero-Crossing principle to the problem of incoherent detection of a stationary radar target in clutter.
Abstract: This paper describes a zero-crossing principle for detecting weak narrow-band signals immersed in Gaussian noise. This principle leads to a zero-crossing detector (detector II) which is relatively insensitive to system gain fluctuations. Moreover, for the detection of a weak sine wave in noise, zero-crossing detector II performs only 1.2 dB worse than the time-honored square-law detector. An application of the zero-crossing principle to the problem of incoherent detection of a stationary radar target in clutter is discussed.
10 citations
TL;DR: In this article, an expression for the maximum balance obtainable with a magic-T microwave bridge as a function of the variance of the frequency modulation (FM) noise pedestal of the microwave power source when one arm of the bridge is terminated by a dispersive component is derived.
Abstract: An expression is derived for the maximum balance obtainable with a magic-T microwave bridge as a function of the variance of the frequency modulation (FM) noise pedestal of the microwave power source when one arm of the bridge is terminated by a dispersive component. This expression is verified experimentally and the long-term stability of the balance with/without a dispersive component is studied.
10 citations
TL;DR: In this article, the authors derived the signal-to-noise ratio of transistorized constant-current anemometers and constant-temperature Anemometers, in the same bandwidth, and showed that the respective signal-noising ratios are not equal, but do not differ appreciably in a practical case.
Abstract: Expressions are derived for the signal-to-noise ratios of transistorized constant-current anemometers and constant-temperature anemometers. It is shown that the respective signal-to-noise ratios (in the same bandwidth) are not equal, but do not differ appreciably in a practical case. The minimum detectable signal (defined on the basis of unity signal-to-noise ratio and expressed in terms of equivalent turbulence intensity) of a constant-temperature anemometer, operated with a typical 5 micron diameter tungsten hot-wire transducer at a mean air flow velocity of 50 m/s, is shown to be 0.3 percent turbulence, in a direct current to 100 kHz frequency range.
TL;DR: In this paper, a method for estimating the unknown parameters in the power spectral density functions of discrete random processes is presented, where the spectral density function is represented by a ratio of two real polynomials in z. It is assumed that only a finite record of the random process is observed and no knowledge about its probability distribution is required.
Abstract: In many engineering problems, the power spectra of random signals have to be measured. In this paper, a method for estimating the unknown parameters in the power spectral density functions of discrete random processes is presented. The spectral density functions are represented by a ratio of two real polynomials in z. It is assumed that only a finite record of the random process is observed and no knowledge about its probability distribution is required. An estimation procedure is developed. It is shown that the denominator parameter estimates can be first obtained. Then the numerator parameters are estimated by filtering the poles from the spectrum. A four parameter example is given to demonstrate the method.
TL;DR: In this paper, two types of errors are caused by misaligned stators in the rotary-vane attenuator, i.e., the actual attenuation will differ from the indicated attenuation values throughout most of the usable range.
Abstract: Two types of errors are caused by misaligned stators in the rotary-vane attenuator. For each type of error the actual attenuation will differ from the indicated attenuation values throughout most of the usable range of the attenuator. This analysis illustrates that these two types of errors are related to the technique of alignment used in establishing the zero reference of the rotating vane to the stator vanes. Equations pertaining to these errors are discussed and are solved with the aid of tables of attenuation error as a function of vane angle error for rotary-vane attenuators. Graphs of both types of errors are presented determining the parameters needed to establish limits of machining tolerances for each waveguide size.
TL;DR: In this article, the authors describe several recent improvements of the Langmuir-probe and doubleprobe technique, including the ability to display time-varying plasma properties on the screen of an oscillosope.
Abstract: Langmuir-probe and double-probe characteristics corresponding to time-varying plasma properties can be displayed instant by instant on the screen of an oscillosope, provided the variation is periodical or at least meets certain requirements of reproducibility. The technique used, essentially an electronic stroboscope, has been described elsewhere under the name "plasmograph." The aim of this paper is to describe several recent improvements of this technique.
TL;DR: The Mariner IV occultation experiment imposed unique requirements upon the NASA/JPL Deep Space Instrumentation Facility as discussed by the authors, which was necessary to measure extremely small deviations in the frequency to a few parts in 109.
Abstract: The Mariner IV occultation experiment imposed unique requirements upon the NASA/Jet Propulsion Laboratory Deep Space Instrumentation Facility. It was necessary to measure extremely small deviations in the frequency to a few parts in 109. The instrumentation used and the results obtained are described.
TL;DR: In this article, the authors used the traveling-wave reflection at an abrupt impedance mismatch along a transmission line to achieve high-voltage pulse attenuation and measurement fidelity by utilizing the principle of travelingwave reflection.
Abstract: Significant advances have been achieved in high-voltage pulse attenuation and measurement fidelity by utilizing the principle of traveling-wave reflection at an abrupt impedance mismatch along a transmission line. Such "reflection-type" attenuators allow practically distortionless attenuation of the signal, independent of voltage level. Their rise-time response and attenuation factor can be known very accurately because they are free from voltage and temperature effects making them especially suited as high-voltage pulse calibration standards. The rise-time response for such attenuators can readily attain 100 ps or less, a practical limit being about 30 ps.
TL;DR: In this paper, a system of RF voltage calibration in the VHF and UHF ranges is described, where the primary voltage standard is a calorimetric power meter whose impedance is determined accurately.
Abstract: A system of RF voltage calibration in the VHF and UHF ranges is described. The primary voltage standard is a calorimetric power meter whose impedance is determined accurately. The working standards are thermal transfer instruments (thermal converters and micropotentiometers). The methods used to calibrate the working standards against the primary standard are described in detail. Then the calibration of transfer standards submitted by other laboratories is outlined, and procedures and practices which have been found successful are recommended for use by standardizing laboratories.
TL;DR: In this paper, an improved electronic scheme has been developed for measuring exploding wire energy as a function of time, which eliminates the problem of serious errors due to induced voltages resulting from high rates of change of current.
Abstract: An improved electronic scheme has been developed for measuring exploding wire energy as a function of time. It eliminates the problem of serious errors due to induced voltages resulting from high rates of change of current. Such induced voltages can rise to many tens of kilovolts, completely masking the desired signals, unless they are nullified in some fashion. In this scheme only passive circuit elements are used (in contrast to dynamic elements such as amplifiers used in previous schemes) to sense signals and to prohibit or effect cancellation of unwanted induced voltages. It is a useful research tool having application to all types of wire-exploder circuitry (both lumped-constant and traveling wave), to any study or application of exploding wires, and with broad application to any rapid deposition of electrical energy in a resistance. It represents a simplification of measurement technique and circuitry while permitting greater accuracy and operating convenience compared to previous methods. Exploding wire energy up to 9.5 kJ was measured with this scheme applied to a lumped-constant, capacitor-bank type of exploder.
TL;DR: In this paper, the authors used a linear dipole to evaluate the electrical conductivity of rock media from measurements on probes inserted into vertical drill holes, in one case the rock type was (fractured) granite and in another, anorthosite.
Abstract: In a dissipative medium, the radio-frequency input conductance of a linear dipole, whether a bare wire or an insulated wire with its terminals short-circuited to the medium, is simply related to the conductivity of that medium provided the electrical length of the dipole is short. Model measurements were made on dipoles in saline water of known conductivity to test the theory. The feasibility of deducing conductivity of the solution by using both types of antennas as probes was demonstrated. The technique has been utilized to evaluate the electrical conductivity of rock media from measurements on probes inserted into vertical drill holes. Examples are given of measurements variously to depths of 4000 ft. In one of the cases the rock type was (fractured) granite and, in another, anorthosite. In a geophysical crustal sense, data are typical of some near-surface or sedimentary rock conditions. Since such rock media are rarely uniform in their electrical characteristics, the deduced conductivity will be a gross average conductivity of that volume of the rock approximately within the antenna region of the probe.
TL;DR: In this article, the authors proposed a method to match thermistor beads for less than 2?W/°C drift by pairing the dR/dt characteristic of each bead and adjusting the dP/dR characteristic for a match.
Abstract: The temperature compensated thermistor-power meter of the dual bridge design has for many years been the most widely used instrument for microwave power measurement. During these many years very little if anything has been written with regard to the manner or criteria for matching the thermistor beads. This paper attempts to fill that void. The procedure to match thermistor beads for less than 2 ?W/°C drift is to be accomplished by pairing the dR/dt characteristic of each bead and adjusting the dP/dR characteristic for a match. dR/dt of the beads may be determined from resistance data at 90°C and 110°C, and the expression dR/dt = 9.4497 [ln Ra-1.11648 ln Rb + 0.61749] which is derived for 200 ? operating resistance thermistors. The thermistor beads are then paired by selecting such that dR1/dt and dR2/dt are within 1 percent of each other. The conditions necessary for matched dP/dR of the thermistor beads are developed and procedures indicated. The paired beads are installed in the thermistor mount and the constant dP/dR of each bead adjusted for equality by moving the heat sink of one of the thermistors until a balance of the slave bridge and master bridge is obtained simultaneously.
TL;DR: In this article, a discussion of salient aspects of the design, construction, and performance of the National Research Council 2.1-meter cesium-beam frequency standard is presented, with emphasis on the characteristics of the (F = 4)?(F = 3)? transitions as they are affected by a range of microwave power and weak dc-magnetic C-field intensities.
Abstract: A discussion of salient aspects of the design, construction, and performance of the National Research Council 2.1-meter cesium-beam frequency standard is presented. Emphasis is placed on the characteristics of the cesium (F = 4)?(F = 3) ? transitions as they are affected by a range of microwave power and weak dc-magnetic C-field intensities. The technique of C-field determination based on excitation of the (4, -4)?(4, -3) transition is described.
TL;DR: In this article, a superheterodyne transceiver was proposed for a narrowband K-band bridge system by utilizing precise, coherent IF detection, where the transmitter is either frequency-stabilized to a sample cavity by means of a high-gain AFC loop, or phase-locked simultaneously to a Kband harmonic of a VHF quartz oscillator and to a tunable VHF oscillator (VFO).
Abstract: A major sensitivity limitation common to most microwave CW balanced-bridge systems must be attributed to bridge distortion noise, caused by residual FM in the transmitted signal. The described superheterodyne transceiver minimizes this limit for a narrowband K-band bridge system by utilizing precise, coherent IF detection. A phase-locked local oscillator provides means for an arbitrary, stable preselection of the in-phase or quadrature component with the help of a calibrated IF delay line. The transmitter is either 1) frequency-stabilized to a sample cavity by means of a high-gain AFC loop, or 2) phase-locked simultaneously to a K-band harmonic of a VHF quartz oscillator and to a tunable VHF oscillator (VFO). This yields flexibility in a wide range of applications, such as measuring small reflection coefficients, dielectric constants, or magnetic tensor susceptibilities (e. g., in ESR spectroscopy). Analytical expressions for phase and amplitude distortions are derived for a bridge containing one high-Q element. In the systems theory of operation, analytical formulas for the noise spectral densities and the loop errors are given, together with numerical examples. The additional receiver noise, due to residual FM and increased bridge power, is demonstrated by means of measured IF-noise spectra. A cavity-Q measurement with ±1 percent accuracy, using 5-?W incident bridge power, proves the system's capability for measurements of small reflection coefficients.
TL;DR: In this paper, a compensating technique based upon the insertion of a compensator voltage into the multivibrator circuit is presented and discussed, along with relations which may be used to estimate the compensating voltage required at a given operating point to reduce this sensitivity to zero.
Abstract: Those factors which influence the timing cycle of astable and monostable multivibrators are discussed in detail and a relation is derived which may be used to predict the sensitivity of frequency (or pulse width) to supply voltage changes. A compensating technique based upon the insertion of a compensating voltage into the multivibrator circuit is presented and discussed. Several compensating circuits are presented along with relations which may be used to estimate the compensating voltage required at a given operating point to reduce this sensitivity to zero. The efficacy of this compensating technique is illustrated by means of experimental results from several examples.
TL;DR: In this article, the essential nonlinearity characteristics of a phase-sensitive detector are studied theoretically, assuming that the input signal is a sine wave in the presence of additive narrow-band Gaussian noise.
Abstract: The essential nonlinearity characteristics of a phase-sensitive detector are studied theoretically, assuming that the input signal is a sine wave in the presence of additive narrow-band Gaussian noise. Three interesting cases of the nonlinearity of the phase-sensitive detector characteristics are analyzed by means of the expression which has been derived for the output signal-to-input noise ratio as a function of the input signal-to-noise ratio, the reference wave-to-noise ratio, and the phase angle between the input signal and reference wave. In the first case, the detector nonlinearity NA as a function of the input signal-to-noise ratio is determined. In the second and third cases, the detector nonlinearities NB and NC as a function of the phase angle between the input signal and the reference wave are obtained. The results are presented as closed-form analytical expressions. Several interesting cases are plotted as a function of the significant parameters. Besides being important in themselves, the results are of a general interest because they may be used to estimate essential nonlinearities in some other more complicated cases.
TL;DR: In this article, a novel method for the measurement of very low turbulence intensities in fluids, based on a dual heat-transfer transducer and a cross correlator, is described.
Abstract: A novel method for the measurement of very low turbulence intensities in fluids, based on a dual heat-transfer transducer and a cross correlator, is described. The minimum measurable turbulence intensity is shown to vary with the square root of the minimum detectable cross-correlation coefficient ?. The effects of finite additive noise correlation and finite lateral separation between the transducer halves are studied. Details are given of an instrument measuring the normalized cross-correlation coefficient between two time-dependent signals in the frequency range 2 Hz-300 kHz with an accuracy of ±0.05? ±0.01. The described correlator is particularly suitable for measurements of quasi-stationary processes. A variation of 10 percent in the level of either input signal results in a correlation error of less than 0.6 percent.
TL;DR: In this paper, a technique capable of precise comparison of currents in different parts of a network or between different networks is discussed, with proper conditions, with negligible perturbation of the networks under measurement.
Abstract: A technique capable of precise comparison of currents in different parts of a network or between currents in different networks is discussed. With proper conditions, this comparison can be done with negligible perturbation of the networks under measurement. Experiments on a coaxial system at 30 MHz are discussed.
TL;DR: In this paper, the authors proposed a universal voltage potentiometer for accurate dc measurements down to nanovolt levels, which is certified traceable to National Bureau of Standards units using previously published ratiometric techniques.
Abstract: Recent interest in accurate dc measurements down to nanovolt levels has prompted the development of a wide voltage range potentiometer of a new type with 7 dial resolution and extremely high accuracy. The potentiometer design is almost perfectly "neutral." All switch contacts and resistors of the main potentiometer operate at high voltage levels, and contribute thermal EMFs which are attenuated by a factor of ten thousand times (to less than 0.1 nanovolt levels) on the nanovolt range. The device serves as an "autocertified" voltage potentiometer standard. It is certified traceable to National Bureau of Standards units using previously published " ratiometric" techniques and is capable of direct reading accuracy without correction from 2 ppm on the 10-volt range to 10 ppm of setting ±1 nanovolt on the 0.001-volt range. The Thevenin equivalent source resistance of the instrument is approximately 2.5 ohms on the 0.001-volt range, reducing Johnson noise levels to less than 1 nanovolt with practical null detector smoothing times. The instrument is designed so that it can be used both as a potentiometer and as a 7-dial Kelvin-Varley divider. The control portion of the instrument is separately packaged and can convert dividers now in use to this new type of universal potentiometer standard. This paper includes a complete theoretical study of the design characteristics of this state of the art potentiometer, and an analysis of all sources of error in the completed instrument.
TL;DR: In this article, the authors describe a new synchronous switch employing solid-state electronics, that extends the usefulness of the CRO in viewing transient phenomena in electrical circuits by means of a repetitive trace on the ROC.
Abstract: This paper describes a new synchronous switch employing solid-state electronics, that extends the usefulness of the CRO in viewing transient phenomena in electrical circuits by means of a repetitive trace on the CRO. This device is particularly useful in normal research projects and has a unique place in repetitive and "one-time" switching in power system models such as the conventional transient analyzer and the newer EHV simulators.
TL;DR: In this article, second-order RC filters are synthesized using two voltage amplifiers with gains A1 and A2 as the natural frequency depends on A1 only, and the damping factor depends on a 1 and 2 gain.
Abstract: Second-order RC filters are synthesized using two voltage amplifiers with gains A1 and A2 As the natural frequency depends on A1 only, and the damping factor depends on A1 and A2, these factors can be chosen consecutively by varying the two gains The passive components need not have variable or accurate values This feature is particularly useful in the realization of filters operating below 1 Hz, and cutoff frequencies down to at least 10-3 Hz can be obtained by exploiting the high input resistance of MOS transistors
TL;DR: The availability of precision coaxial connectors which meet the specifications of the IEEE Subcommittee on Precision Coaxial Connectors has removed an important obstacle to the development of higher accuracy measurements systems over the frequency range from audio to 18 GHz as mentioned in this paper.
Abstract: The availability of precision coaxial connectors which meet the specifications of the IEEE Subcommittee on Precision Coaxial Connectors has removed an important obstacle to the development of higher accuracy measurements systems over the frequency range from audio to 18 GHz. Some of the advances in techniques and standards which have resulted or are presently possible for measurements of impedance, VSWR, attenuation, phase, power, and dielectric properties of materials are reviewed. Problems relating to the connection of unknowns and standards to the terminals of an instrument are discussed with respect to measurements at audio frequencies, radio frequencies, and microwave frequencies.