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Proceedings of the IRE

Issue 5 • Date May 1949

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Displaying Results 1 - 24 of 24
  • Table of contents

    Publication Year: 1949 , Page(s): 465
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  • Harold A. Zahl, Director, 1949

    Publication Year: 1949 , Page(s): 466
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  • Proposed Standard Frequency-Band Designations

    Publication Year: 1949 , Page(s): 467
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  • Theoretical Limitations on the Rate of Transmission of Information

    Publication Year: 1949 , Page(s): 468 - 478
    Cited by:  Papers (14)
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    A review of early work on the theory of the transmission of information is followed by a critical survey of this work and a refutation of the point that, in the absence of noise, there is a finite limit to the rate at which information may be transmitted over a finite frequency band. A simple theory is then developed which includes, in a first-order way, the effects of noise. This theory shows that information may be transmitted over a given circuit according to the relation H ≤ 2BT log (1 + C/ N), where H is the quantity of information, B the transmission link bandwidth, T the time of transmission, and C/N the carrier-to-noise ratio. Certain special cases are considered, and it is shown that there are two distinctly different types of modulation systems, one trading bandwidth linearly for signal-to-noise ratio, the other trading bandwidth logarithmically for signal-to-noise ratio. The theory developed is applied to show some of the inefficiencies of present communication systems. The advantages to be gained by the removal of internal message correlations and analysis of the actual information content of a message are pointed out. The discussion is applied to such communication systems as radar relays, telemeters, voice communication systems, servomechanisms, and computers. View full abstract»

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  • Some Relations between Speed of Indication, Bandwidth, and Signal-to-Random-Noise Ratio in Radio Navigation and Direction Finding

    Publication Year: 1949 , Page(s): 478 - 488
    Cited by:  Papers (4)
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    Rate of phenomenon change and required speeds of indication are quite slow in many navigational and direction-finding systems, particularly those for long ranges. Therefore, the actual total required electrical bandwidths are also quite narrow, probably never greater than 100 cps or so, and in most cases much less than this. Even with complex wave forms, such small total bandwidths are possible if there can be designed a discontinuous-type bandpass filter having a multiplicity of very narrow pass bands occurring at the steady-state Fourier components of the complex signal; i.e., a "comb" filter. One practical method of producing such a discontinuous pass band is described briefly. In view of the interest in new modulation schemes which give an output signal-to-noise ratio which is better than the input carrier-to-noise ratio, it is pointed out that all such systems have improvement thresholds, and many navigational systems provide satisfactory information at output signal-to-noise ratios lower than these threshold values. When this is the case, single-sideband and doublesideband amplitude modulation produce the most sensitive systems. When postdetection bandwidth is very much narrower than predetection bandwidth, many navigational systems will perform satisfactorily even though the carrier-to-noise ratio at the input to the final detector is appreciably less than unity. When this is so, the phenomenon of "apparent demodulation" is encountered. View full abstract»

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  • Calculation of Ground-Wave Field Strength over a Composite Land and Sea Path

    Publication Year: 1949 , Page(s): 489 - 496
    Cited by:  Papers (4)
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    A brief discussion of the problem is given, together with a description of the three proposed methods of solution. The results of a practical experiment are shown, and curves calculated by the three methods are compared with the observed results. It is shown that the BBC method gives field strengths much nearer to the observed values than the P. P. Eckersley method, and that the method proposed by Millington, while somewhat more laborious to use, also gives results which agree well with observed values. The difference between the three methods is small at low frequencies and when the effect of the discontinuity is not large. View full abstract»

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  • Automatic Frequency Phase Control of Television Sweep Circuits

    Publication Year: 1949 , Page(s): 497 - 500
    Cited by:  Papers (2)
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    This paper describes three different types of automatic-frequency-control circuits: (1) sawtooth type, (2) sine-wave type, and (3) pulse-time type. The sawtooth system forms a sawtooth from the pulse present across the deflection yoke. This sawtooth is compared in phase with the synchronizing pulse to produce a control voltage for frequency phase control of the sweep circuit. The sine-wave type comprises a stable sine-wave oscillator which is controlled in phase and frequency by the synchronizing pulse, and in turn controls the sweep circuit. The pulse-time system measures the area of the synchronizing pulse as it rests on the edge of a shelf. Phase variations change this area, and provide information to control the sweep circuit. View full abstract»

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  • Superregeneration-An Analysis of the Linear Mode

    Publication Year: 1949 , Page(s): 500 - 504
    Cited by:  Papers (8)
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    Although superregeneration is usually discussed as a nonlinear problem, the linear mode is an example of a linear circuit problem with a time-varying parameter. The present analysis determines the effect on the behavior of a tuned circuit when its damping factor is subjected to sinusoidal variation. The amplitude and frequency of this variation are considered the fundamental parameters which distinguish the superregenerator from an ordinary resonant circuit. Sensitivity and selectivity are studied as functions of these parameters. It is shown that the solution of the differential equation predicts the phenomenon of multiple resonance and other wellknown properties of a superregenerator in the linear mode. View full abstract»

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  • A Modulator Producing Pulses of 10-7Second Duration at a 1-Mc Recurrence Frequency

    Publication Year: 1949 , Page(s): 505 - 509
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    The development of a pulse generator and a modulator which will produce pulses of 10-7second duration and 3,000-volt amplitude at a 1-Mc recurrence frequency is described. The modulator is developed for the special case of a nonlinear load impedance consisting of 125 μμf capacitance for the leading half of the pulse and a spark discharge for the trailing half. The high recurrence frequency gives rise to problems not generally encountered in the design of pulse circuits. Other applications, such as the second modulation of a high-recurrence-frequency pulsed carrier with voice frequencies, suggest themselves. A new pulse-generating circuit, capable of producing positive pulses whose duration is one-tenth the period of the 1-Mc input sine wave, is developed. This pulse generator can be operated at moderate power levels sufficient to drive the modulator. View full abstract»

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  • Circuits for Traveling-Wave Tubes

    Publication Year: 1949 , Page(s): 510 - 515
    Cited by:  Papers (5)
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    The comparison between traveling-wave-tube circuits of different geometries can be facilitated by the use of phase velocity, group velocity, and stored energy as parameters. For a given stored energy per unit length, lowering the group velocity with respect to the phase velocity increases circuit impedance (and, hence, gain), increases attenuation, and narrows the band. A filter-type circuit consisting of pillbox resonators is shown to be much inferior electrically to a helix. Expressions are presented showing the effect of gap length in filter-type circuits consisting of pillbox resonators, and the attenuation is calculated for such circuits. View full abstract»

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  • The Effect of Pole and Zero Locations on the Transient Response of Linear Dynamic Systems

    Publication Year: 1949 , Page(s): 516 - 529
    Cited by:  Papers (16)
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    The effect of the locations of the poles and zeros of the transfer function of a linear dynamic system on the locations and the magnitudes of the maxima and minima of the transient response resulting from the application of a step-function input to the system is studied. Consideration is given to the necessary conditions for the production of a monotonic time response, expressed in terms of the pole and zero locations. In general, the results of the investigation are limited to stable low-pass systems, having only first-order poles and no poles on the jω axis. A method of computing the locations and magnitudes of the maxima and minima in the time response is given which allows the calculations to be made in a straightforward and efficient manner. The evaluation of the transient performance of many practical lowpass systems can be simplified considerably by the use of this method. It is shown that, under certain conditions of pole and zero locations, the normalized time response may be well approximated by a single dominant time term. Methods of ascertaining from the pole and zero pattern whether these conditions exist are given. On the basis of the dominant-term approximation, a method is outlined for the design of pole and zero patterns to yield prescribed time-response characteristics of a certain class to step-function inputs. Constant overshoot-factor curves and charts are provided for this purpose and for rapid solution of analysis problems when applicable. View full abstract»

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  • Contributors to the Proceedings of the I.R.E.

    Publication Year: 1949 , Page(s): 530
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  • Correspondence

    Publication Year: 1949 , Page(s): 531 - 533
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  • Institute news and radio notes

    Publication Year: 1949 , Page(s): 534 - 541
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  • Books

    Publication Year: 1949 , Page(s): 541 - 543
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  • The Specialist Writer

    Publication Year: 1949 , Page(s): 544
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  • Atomic Energy Its Release, Utilization, and Control

    Publication Year: 1949 , Page(s): 545 - 547
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  • Quality Control in Radio-Tube Manufacture

    Publication Year: 1949 , Page(s): 548 - 556
    Cited by:  Papers (1)
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    Methods of quality control in the radio-tube manufacturing industry are surveyed. Typical mount-inspection service, use of statistical control charts, and sampling procedures are discussed. View full abstract»

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  • A Field Survey of Television Channel 5 Propagation of New York Metropolitan Area

    Publication Year: 1949 , Page(s): 556 - 563
    Cited by:  Papers (1)
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    A comprehensive study of the performance characteristics of Du Mont television station WABD, New York, N.Y., embracing a new measuring technique, is discussed. A comparison of theoretical and experimental data is illustrated by photographs and charts indicating receiving conditions within the service area. Pertinent information concerning various interference problems is also considered. View full abstract»

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  • Electronic Classifying, Cataloging, and Counting Systems

    Publication Year: 1949 , Page(s): 564 - 568
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    The determination of the distribution of a series of physical events according to magnitude is important in the study of the associated physical laws. Previous methods of determining this magnitude distribution were slow and cumbersome. Three new electronic systems which operate on events at a very high rate have been developed by the author while at Oak Ridge National Laboratory, and these are described. The analyzers can be used to determine the magnitude distribution of any series of physical events, if the characteristic under observation can be translated into a proportional voltage pulse. Two applications are discussed, and the advantages of the analyzers over other systems are shown. View full abstract»

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  • Graphical Analysis of Linear Magnetic Recording Using High-Frequency Excitation

    Publication Year: 1949 , Page(s): 569 - 573
    Cited by:  Papers (4)
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    The addition of a high-frequency component to an audio signal which is to be recorded magnetically results in a low-distortion, linear recording characteristic under certain conditions. This paper gives a graphical method for constructing the recording characteristic from the BRversus H curve of the record material. An analysis accounts for such magnetic-recording characteristics as variation in sensitivity with bias, linearity at low recording levels, adjustment for maximum sensitivity, and adjustment for minimum distortion. View full abstract»

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  • Q Measurements-Two- and Four-Terminal Networks

    Publication Year: 1949 , Page(s): 573 - 577
    Cited by:  Papers (1)
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    Considering the equivalent circuit of a simple shunt-resonant four-terminal network, including loss, equations are derived permitting the calculation of unloaded and doubly loaded Q's, and the resonant frequency, from standing-wave-ratio or transmission-coefficient measurement at three arbitrary frequencies or wave-lengths. The equations are then put in a convenient form for data taken on a "triple-pipper impedance bridge." Finally, the equations are given for the same type of measurement for a two-terminal network, giving the unloaded and loaded Q's. View full abstract»

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  • Contributors to Waves and Electrons Section

    Publication Year: 1949 , Page(s): 577 - 578
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  • Abstracts and references

    Publication Year: 1949 , Page(s): 579 - 592
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Aims & Scope

This Periodical ceased production in 1962. The current retitled publication is Proceedings of the IEEE.

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