By Topic

Instrumentation and Measurement, IEEE Transactions on

Issue 4 • Date Dec. 1969

Filter Results

Displaying Results 1 - 25 of 28
  • [Front cover]

    Publication Year: 1969 , Page(s): c1
    Save to Project icon | Request Permissions | PDF file iconPDF (33 KB)  
    Freely Available from IEEE
  • IEEE Instrumentation and Measurement Group

    Publication Year: 1969 , Page(s): c2
    Save to Project icon | Request Permissions | PDF file iconPDF (170 KB)  
    Freely Available from IEEE
  • Table of contents

    Publication Year: 1969 , Page(s): 245
    Save to Project icon | Request Permissions | PDF file iconPDF (171 KB)  
    Freely Available from IEEE
  • Preface

    Publication Year: 1969 , Page(s): 246
    Save to Project icon | Request Permissions | PDF file iconPDF (59 KB)  
    Freely Available from IEEE
  • Measurement of Nonlinear Phase Distortion in Microwave Limiters under Dynamic Conditions

    Publication Year: 1969 , Page(s): 247 - 251
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2444 KB)  

    Nonlinear phase distortion (amplitude-modulation to phase-modulation conversion) in microwave limiters can be different under static and dynamic conditions. A technique for measurement of dynamic phase distortion is described in which a two-tone test signal is used to simulate amplitude modulation with modulating frequencies of the order of megahertz. The two-tone test signal is generated by linearly summing two equal-amplitude sine waves. The result is a constant-frequency amplitude-modulated signal whose envelope varies as a rectified cosine wave at the beat frequency of the two sine waves. There is no phase deviation except at the envelope zeros, where the phase jumps 180°. Measurements are made by splitting the output signal from the limiter into two identical signals and delaying one relative to the other by approximately an odd multiple of one-half the envelope period. The two signals, when displayed on an X-Y cathode-ray tube, produce a pair of filled-in ellipses with major axes at 45° and and 135°. Peak phase deviation is obtained by direct measurement of either ellipse. Measurement data in E band are given for two tunnel-diode amplifier-limiters, a balanced mixer-limiter, and a traveling-wave-tube amplifier followed by a balanced mixer-limiter. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Frequency-Domain Interpretation of Oscillator Phase Stability

    Publication Year: 1969 , Page(s): 251 - 261
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2192 KB)  

    A frequency-domain interpretation of the phase stability of an oscillator is discussed. From a knowledge of the time dependence of an oscillator phase during a time interval T* it is possible to give the characteristics of this oscillator, not only for this time interval, but also for subsequent time intervals. Since the use of a Fourier transform for the computation of a continuous power spectrum is unrealistic, a discrete-spectrum approach will be taken. Usually, in the calculation of power spectra, stationarity of the fluctuations is assumed, although experiment indicates that this is often not the case. A more realistic approach is adopted. Analytical phenomena and random walk are separated from white noise on the basis of statistical criteria using discrete Fourier transforms. The white noise is then interpreted in the frequency domain. Both random walk and specific signals are studied in the time domain and can be separated by digital filtering. Two different sets of experimental results are analyzed by this method, one derived from measurements on a quartz-crystal oscillator locked to a low-frequency transmitter and the second from measurements on an ammonia maser. In both cases, measurement precision and ease of prediction of the behavior of the oscillator are improved. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • The Application of the Compensated Current Comparator to the Calibration of Current Transformers at Ratios Less than Unity

    Publication Year: 1969 , Page(s): 261 - 265
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (860 KB)  

    A technique is described for extending the range of the compensated current comparator so that it may be used for calibrating current transformers at ratios both greater and less than 1/1. The concept of providing compensation windings for both the primary and secondary ratio windings is introduced and a new method of correcting for the capacitance error due to burden is presented. Details on how a compensated current comparator previously developed for ratios from 1/1 to 240/1 may be adapted for this purpose are discussed and results of measurements at ratios down to 0.01/1 with this comparator are given. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A Direct-Current-Comparator Bridge for Measuring Shunts up to 20000 Amperes

    Publication Year: 1969 , Page(s): 266 - 271
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2259 KB)  

    A direct-current-comparator bridge for calibrating four-terminal resistors or shunts at currents up to 20 000 amperes is described. Measurements can be made at up to full rated current of the shunts so that the effects of the load coefficient are included. The resistor under test is compared with a reference resistor of higher value by measuring the ratio of the currents through the two resistors required to produce equal voltages across them. A comparator bridge with a range of 100 amperes and errors of less than 1 ppm has been described previously. Improvements to this bridge have been made, the main one being a reversing feature, which permits the currents through the resistors to be reversed in a few milliseconds. This makes an accurate measurement easier, particularly if there is a change of resistance due to heating. By connecting a second comparator in cascade, the range has been extended to 20 000 amperes at an overall ratio up to 2 × 106: 1, with only a slight loss of accuracy; the errors may be a few parts per million. Other applications of the measuring system are the accurate measurement of large currents or the calibration of transductors. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Detection of Shifts in the Values of Saturated Standard Cells Used as References

    Publication Year: 1969 , Page(s): 271 - 276
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1429 KB)  

    A method of analyzing data taken in routine comparisons of a test group of saturated cells to a reference group, so that shifts in the electromotive forces of individual reference cells may be detected, is explained. Limitations on the minimum number of reference cells adequate for close tracking of cells under text become apparent from examination of data, as do the advantages of knowing precisely the electromotive force of each reference cell at the time of use. The technique is suggested as a convenient means of augmenting surveillance of the stability of individual reference cells with respect to the average of a larger group. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Ratio Comparisons of Impedance Standards

    Publication Year: 1969 , Page(s): 276 - 283
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1765 KB)  

    The application of a readily assembled comparator circuit, previously used in the comparison calibration of inductive and resistive voltage dividers, has been extended to cover the comparison of impedance standards. As an example requiring the most stringent performance from the circuit, the comparison of four-terminal inductance standards and their absolute determination in terms of the unit of capacitance have been studied. A data-reduction procedure has been devised to utilize a partial set of pair-wise comparison measurements to establish the absolute scale of inductance from 10 henrys to 500 ¿H. A realistic assessment of system errors has been incorporated in the data reduction, which establishes the absolute accuracy at approximately 0.003 percent over the whole range. Determination of the quality factor Q of the inductors to better than 0.2 percent has also resulted from these measurements, principally at 1 kHz. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A Semi-Automatic Method for the Precision Measurement of Microwave Impedance

    Publication Year: 1969 , Page(s): 283 - 289
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1997 KB)  

    A system is described for the measurement of the magnitude and phase of the reflection coefficient over wide frequency bands. The method consists of recording the voltage at several points along the standing-wave pattern in a coaxial line. A fixed probe is used and the distance between the probe and the load is altered by successively inserting several lengths of precision coaxial line. Knowing these lengths and the frequency of the signal, a curve representing the standing-wave pattern is fitted to the experimental points by means of a computer program performing a least-squares minimization. To cover a given frequency band, the frequency is changed in discrete steps and the corresponding probe voltage recorded automatically. The measured impedance is referred directly to the characteristic impedance of air-dielectric coaxial lines. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • An Octave-Band Microwave Phase Comparator

    Publication Year: 1969 , Page(s): 290 - 294
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1685 KB)  

    A simple apparatus for measuring the relative phase difference between two signals of identical frequency anywhere within an octave band at microwave frequencies is described. Instantaneous measurements can be performed upon carriers that are periodically 100 percent modulated by narrow pulses since no mechanical contrivances are required. Phase information is converted by detectors into four channels of amplitude information, and these are then combined to yield a relative phase measurement that is unambiguous over a 360° range. In principle, the method is independent of relative signal amplitudes, but in practice it is limited by the useful range of the detectors. Two power dividers, a 90° coupler and a 180° hybrid, four detectors, and an oscilloscope comprise the necessary basic hardware. A derivation of the basic principles of the phase comparator is presented, together with a discussion of calibration test results, for every 10° in phase at each of nine separate frequencies over an octave band. Finally, a processing device for generating a digital indication of relative phase angle is also described. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Computer Applications for Parameter Control and Data Processing in a Metrology Laboratory

    Publication Year: 1969 , Page(s): 294 - 299
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1511 KB)  

    A computer-oriented program for control and dissemination of measurement parameters as applied in a metrology laboratory is described. The program includes the capability for automated data readout of certain measurement systems as process inputs, computer storage and statistical analysis of "absolute" values of fixed standards, computer data computation incorporating all known information on measurement-system entities, and parameter status control. The preparation of reports of calibration by computer output is provided for repetitive services. Operational details of the program as applied to the dc/LF region of capability are discussed. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Computer Augmented Oscilloscope System

    Publication Year: 1969 , Page(s): 299 - 306
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3413 KB)  

    The Computer Augmented Oscilloscope System (CAOS) is a laboratory-computer terminal intended for experiments involving waveforms and their interpretation. The terminal is portable and can be used wherever telephone access to a suitably programmed computer is available. The CAOS laboratory equipment includes a sampling oscilloscope with a storage CRT, the terminal proper, and a telephone line connection. The terminal includes alphameric and function keyboards, A/D and D/A converters, a read-only store character generator, sequencing and control logic, and circuits for interfacing to the oscilloscope and the telephone line. CAOS is an interface between the experimenter, the experiment, and the computer. It provides digital acquisition of waveform data, system calibration, data analysis, experiment control, and graphic and alphameric display. CAOS can emulate a number of laboratory instruments and can operate additional X-Y storage oscilloscopes. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Automatic Transformation of Curved-to-Flat Calibration Lines by a Normalizer

    Publication Year: 1969 , Page(s): 307 - 316
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2471 KB)  

    In high-accuracy swept-frequency insertion-loss testing, antenna-pattern measurement, and many other applications, significant measurement-system output variations are caused by the system itself. These variations can be recorded and subtracted from the measurement results to provide the required accuracy generally by recording system calibration lines with attenuation standards in the test position and reading the measurement results against these calibration lines. However, the procedure is tedious, costly, and does not lend itself to automation. The linearizer is a device for storing the system calibration and correcting for it before displaying the results. With no loss in accuracy, it provides an output curve that can be read on an ordinary rectilinear graph, used to actuate GO-NO GO switches, or automaticaly compare a test piece against a standard. Details of operation and some performance data are given for a particular analog-type linearizer and associated swept-frequency measurement system for insertion-loss or scattering coefficients. The linearizer can readily display a scale of 0.02 dB/inch with adequate stability and reproducibility. Two such linearizers can be used together to display two components of a vector or phase and amplitude, etc. Other applications are discussed and several possible approaches to an ideal system shown. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Digital Walsh-Fourier Analysis of Periodic Waveforms

    Publication Year: 1969 , Page(s): 316 - 321
    Cited by:  Papers (16)  |  Patents (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1188 KB)  

    A digital process is described for obtaining the Walsh-Fourier series of a periodic waveform, which requires at most two cycles of the waveform under measurement. The first cycle of the periodic waveform is required for the determination of period. The coefficients of the Walsh-Fourier series are obtained during the second cycle only, and they are available at the end of the cycle. Given the Walsh-Fourier coefficients of the periodic wave, the individual sine and cosine components of its Fourier series may be obtained using conversion formulas. Special features of the process are that there are no theoretical low-frequency limitations, and for an instrument with an internal clock whose frequency lies in the range 1 Hz to 1 MHz, the fundamental frequency component of a signal that can be analyzed would be in the range 1 cycle in 11.6 days to 60 Hz. Also, whereas the digital processes required to obtain a Fourier series directly are complicated by the need to multiply sample values of voltage by sines and cosines, which are themselves functions of time, determination of Walsh-Fourier coefficients is achieved very simply by using gating circuits. Generation of the required Walsh functions for a periodic signal of any fundamental frequency within the design range has been achieved. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Finding the RMS Value of a Fading Signal Directly and Quickly from Its Decibel Values

    Publication Year: 1969 , Page(s): 321 - 326
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1155 KB)  

    Two methods are proposed for obtaining the rms value of a fading signal directly and quickly from its decibel values. The level-crossing-rate method shows that the rms values of most kinds of signals are within 3 dB above the signal levels at which their maximum level crossing rates occur. The direct method shows that the difference between the average of a decibel-scale fading-signal datum and the rms value of the signal is within 2.5 dB for most of the fading signals. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • The Attenuation of a Pulsed Field by a Conducting Sheet

    Publication Year: 1969 , Page(s): 326 - 330
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (905 KB)  

    Instruments that produce pulsed eddy currents in metals have been used to measure the thickness of one metal on another and to determine the properties of metals. The currents are produced by a pulsed dipole, which is surrounded by a conducting mask with a small aperture near the metal to concentrate the field and thus provide better resolution. A pickup coil near the metal is used to detect the currents. One configuration had the pickup coil on one side of a thin metal sheet with the aperture on the other side. This was analyzed assuming a plane electromagnetic wave with the magnetic field parallel to the surface of the metal. Experimental measurements showed that the attenuation as measured was about one-tenth that predicted by the analysis. An analysis was then made assuming that the magnetic field entered the metal surface perpendicularly to the surface. The results of this analysis were compared with the experimentally obtained results with good agreement. Possibly the main reason for the failure of the earlier plane-wave analysis was the reflection at the metal surfaces. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Broad-Band Remote-Sensing Magnetometer

    Publication Year: 1969 , Page(s): 330 - 335
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3263 KB)  

    A broad-band remote-sensing magnetometer system has been developed for measuring fast-rising pulsed magnetic fields. Broad frequency response is achieved by frequency modulating a 1.5-GHz microwave carrier for transmission from the sensor to a remotely located receiver. The primary field probe is a ferrite-loaded coil, which produces a current proportional to the magnetic-field intensity. This current is used to frequency modulate a YIG-tuned transistor oscillator in the sensor. A traveling-wave amplifier in the receiver provides carrier amplification and amplitude limiting because it is operated in saturation mode. A new type of FM discriminator, which offers multiple-octave bandwidth potential, converts the frequency-modulated carrier to an amplitude-modulated carrier. The signal is finally detected and amplified for oscilloscope display. While the present system achieves a 50-MHz bandwidth, the system concept should be capable of extension to several times this bandwidth. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • On a Class of Capacitively Tuned Transducer Oscillators

    Publication Year: 1969 , Page(s): 336 - 340
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1059 KB)  

    A class of transducer oscillators is characterized by a tuning method that exchanges short-term for long-term stability, and accepts both single and differential tuning sensor capacitances. When the tuning method is applied to a restricted class of RC oscillators, the relation between tuning capacitance and oscillator period can be made linear. The effect of amplifier phase shift and distortion is analyzed and a design procedure given. In one application, an oscillator used with an air-pressure sensor is tuned from 25 to 50 ms (corresponding to 40 to 20 Hz) with a differential tuning capacitance varying from -2 to + 7 pF. The short-term stability is 80 ppm when the average of 100 periods is measured. The deviation from linearity is less than 1.5 percent of the total range. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A Simple Pulse-Height Analyzer for Partial-Discharge-Rate Measurements

    Publication Year: 1969 , Page(s): 341 - 345
    Cited by:  Papers (37)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1877 KB)  

    A single-channel pulse-height analyzer with suitable pulse-shaping circuits designed for partial-discharge measurements is described. The circuit of the pulse-height analyzer has a basic resolution limit of 1.5 ¿s. The unit may be used in conjunction with an RLC-type partial-discharge-detection circuit and is thus applicable to discharge measurements on high-voltage apparatus such as transformers, capacitors, and cables. Typical results, obtained with an artificial void simulated with metallic-dielectric electrodes, are presented. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • IF Return-Loss Measurements in Microwave Radio Systems

    Publication Year: 1969 , Page(s): 346 - 352
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2713 KB)  

    The basic designs and several applications of a ferrite-core transformer bridge that realizes a directivity better than 60 dB are described. The bridge is intended for use in IF return-loss measurements of microwave and satellite systems operating from 50 to 100 MHz. The bandwidth of the unit extends from 5 to 200 MHz. The main feature of the balanced transformer is the use of a symmetrical primary winding in which the applied signal is tightly coupled into a reversed neutralizing winding. This method virtually eliminates capacitively coupled unbalance components that normally exist in such a transformer. The applications include an unusual approach to measurement of the source impedance of a generator on its own signal. It is referred to as the amplified double-reflection method and uses a second bridge with an amplifier to provide significant improvement in obtainable resolution over conventional cable-reflection methods. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Instrumentation-The Future

    Publication Year: 1969 , Page(s): 352 - 361
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3668 KB)  

    First Page of the Article
    View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Contributors

    Publication Year: 1969 , Page(s): 361 - 364
    Save to Project icon | Request Permissions | PDF file iconPDF (4439 KB)  
    Freely Available from IEEE
  • Abstracts of Other Papers

    Publication Year: 1969 , Page(s): 365 - 367
    Save to Project icon | Request Permissions | PDF file iconPDF (621 KB)  
    Freely Available from IEEE

Aims & Scope

Papers are sought that address innovative solutions to the development and use of electrical and electronic instruments and equipment to measure, monitor and/or record physical phenomena for the purpose of advancing measurement science, methods, functionality and applications.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Prof. Alessandro Ferrero
Dipartimento di Elettrotecnica
Piazza Leonardo da Vinci 32
Politecnico di Milano
Milano 20133 Italy
alessandro.ferrero@polimi.it
Phone: 39-02-2399-3751
Fax: 39-02-2399-3703