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Instrumentation, IRE Transactions on

Issue 3 • Date Dec. 1962

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Displaying Results 1 - 25 of 52
  • [PDF Not Yet Available In IEEE Xplore]

    Page(s): c1
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    Freely Available from IEEE
  • [Table of contents]

    Page(s): 81
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  • Measurement Problems of Space Vehicle Experiments

    Page(s): 86 - 96
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    The need for conducting remote measurements by use of experimental sensors on space vehicles, in an environment where there is often a large uncertainty in the parameter to be measured, establishes a new area of endeavor for the researcher. The conditions peculiar to this problem are in many instances vastly different from those normally encountered in laboratory research, and are related to the over-all spacecraft design requirements. These new conditions attach a new significance to calibration philosophy, sampling rates, conversion accuracies, and reliability. Furthermore, the ground data handling problem of extracting information from the large quantities of data is extremely severe and usually requires careful planning by the experimenters several months prior to the actual measurement. The purpose of this paper is to survey the current and future aspects of acquiring accurate and intelligible information from the spacecraft sensors by the utilization of techniques which tend to be more compatible with the spacecraft design requirements. View full abstract»

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  • A Direct Measurement of Charge Density in the F2 Region

    Page(s): 96 - 99
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    A measurement of the charge density in the F2 region was made in 1962 with an ion trap mounted on an oriented satellite. Orbital monitoring of ionospheric characteristics continued for about four days. Current from collected ions, grid modulated by a triangular sweep voltage, indicated charge density, temperature, vehicle potential and some information on ion mass ratios. The current-measuring circuitry consisted of a hybrid electrometer followed by two amplifiers of similar circuit design. Determined ion kinetic temperatures were 1500°K and higher; ion concentrations varied from 5×103 to 106 ions/cm3 over latitudes of 73°N to 73°S. View full abstract»

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  • Automatic Range Switching of Instrumentation in Space Vehicles for Increased Accuracy

    Page(s): 100 - 102
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    This paper describes an instrument, suitable for space flight, which automatically switches the range of a measuring instrument, and thus makes possible accurate measurements of electronic signals that vary by several orders of magnitude. The accurate measurement of current, voltage, or pulses, etc., that vary by several orders of magnitude has been a difficult problem. Wide dynamic ranges of this type are necessary, for instance, in accurate mass spectrometer or density measurements in the upper atmosphere. The instrument described accomplishes this with low power and in a small space by computer-type circuitry. View full abstract»

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  • Lunar Surface and Subsurface Magnetic Susceptibility Instrumentation

    Page(s): 102 - 106
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    Multicoil induction measurements of the lunar surface and subsurface magnetic susceptibility are under study. Major considerations are the improvement of the accuracy and logging ability of various probe configurations. Special boundary conditions of high vacuum, extreme ambient temperature variation, restriction to mechanically passive systems, simple electronics, low power and light weight all contribute to degradation of the accuracy of the instrument. Measurements in the range of 10 to 100,000 micro-oersted/gauss are of interest. Nonsedimentary rocks range from 40 to 1000 ¿-oersted/gauss and the presence of nickel-iron meteoritic material may extend the range beyond the present limits of measurement. The determination of the presence or absence of meteoritic material is necessary to validate not only the accuracy of the susceptibility measurement, but also the accuracy of low level magnetometer measurements. View full abstract»

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  • Absolute Magnetic Susceptibilities by the Gouy and the Thorpe-Senftle Methods

    Page(s): 106 - 109
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    Using the Curie-Cheneveau principle, A. Thorpe and F. E. Senftle have developed an absolute yet simple force method for measuring the magnetic susceptibilities of very small samples. In our laboratory an apparatus was constructed so that absolute susceptibilities could be determined by both the Thorpe-Senftle and the Gouy methods down to liquid helium temperatures. Measurements were made on powdered samples of the same batch of (NH4)2OsBr6, HgCo(SCN)4, and Fe(NH4)2(SO4)2·6H2O. Comparable accuracies were obtained by the two methods; however, about 3 ×10-2 as much sample is required to do a Thorpe-Senftle measurement. View full abstract»

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  • The Design and Performance of High-Precision Audio-Frequency Current Transformers

    Page(s): 109 - 114
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    The causes of error with increasing frequency in current transformers of existing design are examined. A new approach in design is suggested and equations are developed from which the performance can be calculated for a variety of operating conditions over a wide band of audio frequencies. Practical details are given of a group of multiratio transformers rated from 5/5 to 400/5 designed for the range 400 cps to 20 kc. View full abstract»

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  • A New Peak-to-DC Comparator for Audio Frequencies

    Page(s): 115 - 122
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    An adjustment-free peak-to-dc transfer technique is described for making precision comparisons between audio frequency ac voltages and a reference dc. Limitations and estimated systematic errors are discussed and justifications for an over-all ac-dc transfer worst case error of 50 ppm presented. Photographs of output oscilloscope patterns are shown for various conditions of ac-dc transfer agreement for several different ac sources. Experimental over-all comparison against a modification of the Smith-Clothier peak calibration technique is described with agreement on the order of 30 ppm. View full abstract»

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  • Low-Power-Operated DC Instrument Transformers

    Page(s): 122 - 127
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    In view of the various applications of nonlinear-magnetic control devices in earth-satellite equipment with solar-battery supply, a low-power-operated prototype design of a miniaturized dc instrument transformer with single-turn or multiturn control has been recently developed. This design combines a saturable-reactor push-pull circuit with a battery-supplied switching-transistor magnetic-core multivibrator. When measuring a direct current in the range 0 . . . 1 a, the four toroidal cores of the push-pull circuit link the wire, which carries this current and acts as a single-turn control winding. The corresponding dc output voltage of this circuit (0 . . . 5 v) is polarity-reversible and linearly proportional to the current to be measured. In this case, application of the single-turn-controlled dc instrument transformer eliminates the considerable power dissipation (up to 5 w) in a 5-ohm shunt resistor carrying the current to be measured. Smaller currents are measured with multiturn control where the wire carrying the control current can be threaded through the window opening for 2, 5, or 10 turns to give 5-v rated output-voltage value for 0.5-, 0.2- or 0.1-a control current, respectively. DC voltages of the order of 1 to 100 volts can be measured indirectly by employing the current range 0 . . . 100 or 0 . . . 200 ¿a, control windings with 10,000 or 5000 turns, and a series resistor corresponding to the multiplier resistor of an ordinary dc voltmeter. View full abstract»

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  • A Direct Reading Voltage Divider with Standard Cell Reference

    Page(s): 128 - 132
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    A highly accurate Direct Reading Voltage Divider has been developed in which the output voltage is equal to that of a standard cell when the input resistance has been adjusted so that 1 ma of current is flowing through the divider. The range of measurement with direct reference to a standard cell is from 2 to 1100 v. The range may be lowered to 0.02 v with decreased accuracy by the use of a Lindeck potentiometer in place of the standard cell. The stability, repeatability and calibration accuracy of the divider have been evaluated. Results indicate that accuracies of approximately 0.005 per cent may be obtained from 2.0 v to 1100 v without applying corrections. Design, evaluation and certification of the divider will be discussed. View full abstract»

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  • Uncertainties in Calibration

    Page(s): 133 - 138
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    This paper presents some methods for making comparisons between standards and items undergoing calibration. These methods may be used in a variety of measurements. The purpose is to accumulate data that provide objective estimates of the precision and that are also useful in detecting sources of systematic errors. This purpose is achieved in using some standard statistical designs in the scheduling of the work program. The problems of stating the uncertainty and of combining the uncertainties in a chain of calibrations are discussed. View full abstract»

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  • The Speed of Light

    Page(s): 138 - 148
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    Numerous measurements of the speed of light published during the last 30 years lead to widely divergent results as compared with the assigned experimental uncertainties. Because of wide diversity in the methods employed in the measurements, all of the data may not be combined effectively in a grand average. Sufficient data had been obtained by the geodimeter method to group them and derive a statistical estimate of the uncertainty in the speed of light by this method. This result, and conclusions reached from careful examination of several experiments, leads to the conclusion that the value 299,792.5 km which has been internationally adopted for use in radio propagation and geodetic work is very close to the best value and not likely to be in error by as much as one part in one million. View full abstract»

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  • Automatic DC Data Logging System

    Page(s): 148 - 152
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    A system is described which digitizes dc voltages and records the values on punched cards for subsequent machine data reduction. High accuracy is achieved by comparing the input voltage to a bank of standard cells and measuring the difference. An automatic calibration routine is provided. Resolution is one part per million, stability a few parts per million for a 30-day period without adjustment. Contributions of various parts of the system to over-all error are analyzed. Automatic calibration data are analyzed to establish system performance. View full abstract»

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  • Variance of Radio Frequency Caused by Atmospheric Turbulence in Line-of-Sight Transmissions

    Page(s): 153 - 155
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    The frequency stability of a radio signal propagated over a line-of-sight path is reduced by time variations in phase velocity along the path. This instability caused by the atmosphere will produce errors in frequency measurements made by averaging a standard frequency transmission over a period of time T and also in time interval measurements made by counting the number of cycles of the standard frequency received during a period of time T. Recent measurements of the variations in phase of a received signal at microwave frequencies permit estimation of both types of error as a function of T. These atmosphere-induced errors are compared to the errors inherent in the best currently-available cyrstal oscillators and it appears that the latter source of error is dominant for line-of-sight paths through the atmosphere. The level and slope of the frequency spectra have been observed to vary over wide ranges with time and geographical location. The spectral form W(f)~f-2/3 expected on the basis of the Obukhov-Kolmogorov theory of atmospheric turbulence has a slope which lies will within the range of observed slopes for the range of fluctuation frequencies from 1 cycle/day to 1 cps. View full abstract»

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  • Microwave Faraday Rotation Using a Bimodal Cavity

    Page(s): 156 - 159
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    A technique has been developed for using a bimodal cavity to measure Faraday rotation at microwave frequencies with high sensitivity. Such measurements yield information about the off-diagonal elements of either the susceptibility or conductivity tensor of the sample being investigated. This paper presents a qualitative discussion of the behavior and use of this cavity. Previously presented analysis of the cavity operation is outlined and the measurements made to date, using the cavity, are indicated. View full abstract»

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  • The Microwave Measurement of Narrow Line Width Ferromagnets by Radiated Fields

    Page(s): 159 - 162
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    A simple waveguide method for measuring narrow line widths of ferromagnets is discussed. The precision reported from the measurement of a single crystal YIG sphere is ¿H=0.55±0.02 oersted. The equipment used is capable of modification for more precise measurements. View full abstract»

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  • Measurement and Standardization of Dielectric Samples

    Page(s): 162 - 165
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    The selection of a material suitable for use as a standard of dielectric properties at microwave frequencies is discussed, and tests are described which indicate that a glass and a glass ceramic are satisfactory for such standards. The probable accuracy of measurement of the real part of the dielectric constant is estimated at ± 0.3 per cent. Loss measurements are discussed. A correction is developed for the error resulting from the small airgap often present around the sample in transmission-line measurements. The effects of humidity and temperature variations are examined, and preliminary results of measurements to 800°C are given. View full abstract»

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  • The Proton Magnetic Resonance Oscillator, a Radio Frequency Source of High Spectral Purity

    Page(s): 166 - 170
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    Some basic properties of a proton maser making use of the dynamic Overhauser effect for population inversion and enhancement are reviewed. The long proton spin relaxation times of liquid samples, in the order of seconds, facilitate the production of self-sustained continuous oscillation with high spectral purity. Theoretically the proton maser oscillator should have a spectral purity of some parts in 1014 for an inhomogeneously broadened proton resonance absorption linewidth of 100 cps at a frequency of 15 Mc. A proton maser was operated at this frequency in a temperature stabilized permanent magnet. In preliminary experiments a frequency drift in the order of 1 part in 109/sec was measured. The spectral purity was tested by beating together the frequencies of two proton maser oscillators operating within the same magnetic field. Preliminary results yielded frequency deviations of less than 6 parts in 1010. The sources introducing frequency instability are discussed and their relative contributions evaluated. View full abstract»

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  • The Measurement of Voltage by the Use of the Star Effect

    Page(s): 171 - 176
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    The theory of the Stark effect is reviewed with regard to its possible application of measuring voltages. It is pointed out that the effect can be used only to measure relative voltage and that the accuracy is likely to be limited by the accuracy with which the electrode separation can be determined. Therefore, the most sophisticated types of molecular frequency standards may not be required. The Stark method appears to hold a particular advantage for the measurement of high voltage since no voltage divider is required. Also, two possible methods of comparing ac voltages to dc voltages are discussed. Finally, an experimental Stark voltmeter employing a millimeter wave Fabry-Perot absorption cell is discussed. Calculations concerning J=2¿3 transition of methyl cyanide at 55 Gc indicate that in principle the precision obtainable with a field strength of 104 volts/cm should be in the neighborhood of one part in a million, if the effects of field inhomogeneities can be kept within comparable limits. View full abstract»

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  • The Atomic Hydrogen Maser

    Page(s): 177 - 182
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    The atomic hydrogen maser is described. In this device hydrogen atoms in the upper hyperfine state are focused onto the entrance aperture of a Teflon coated quartz bulb in which the atoms are stored for about a second. This bulb is surrounded by a cylindrical radiofrequency cavity; When the cavity is tuned to the hyperfine frequency of atomic hydrogen, maser radiation is produced. Due to the large line Q resulting from the long storage time, the radiation is highly stable in frequency. Results are given of theoretical calculations on the threshold flux of atoms required for maser oscillations, on the various relaxation processes that limit the effective storage time and on the possible sources of frequency shifts of the maser. Results are given on the relative stability of two hydrogen masers. View full abstract»

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  • Design and Performance of an Atomic Hydrogen Maser

    Page(s): 183 - 187
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    The design and construction of a relatively compact device for use as a frequency standard is discussed. Hydrogen scavenging is done by titanium sorption pumps having a continuous operating lifetime of one year. The magnetic and thermal shielding of the cavity is described, and frequency errors due to various effects are discussed. Preliminary data of measurements of relative stability between two masers is presented and a means for measuring short- and long-term stability is discussed. View full abstract»

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  • Hydrogen Cyanide Molecular Beam-Type Maser

    Page(s): 187 - 190
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    A hydrogen cyanide molecular beam-type maser has been successfully operated as an oscillator. The maser oscillates at two lines of a hyperfine triplet at 88.633 and 88.631 kMc. The maser uses an interferometer-type confocal resonant cavity. Many molecular beams eject from two circular beam sources radially towards the center of the circle where the cavity is located. The focusers, which separate molecules in the first excited state of the rotational energy spectrum from those in the ground state, consist of two planes. Each plane is composed of radially arranged rods which are charged alternatingly to high positive and negative potentials. View full abstract»

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Aims & Scope

This Transactions ceased publication in 1962. The current retitled publication is IEEE Transactions on Instrumentation and Measurement.

Full Aims & Scope