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Radio Engineers, Proceedings of the Institute of

Issue 2 • Date Feb. 1928

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Displaying Results 1 - 18 of 18
  • [Front cover]

    Page(s): c1 - c2
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  • Contents

    Page(s): 107
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  • General Information

    Page(s): 107
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  • Officers and Board of Direction, 1928

    Page(s): 108 - 110
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  • A. Hoyt Taylor [Recipient of the Morris Liebmann Memorial Prize, 1927]

    Page(s): 112 - 113
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  • Contributors to this issue

    Page(s): 114 - 115
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  • Institute activities

    Page(s): 116 - 123
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  • A Precision Method for the Measurement of High Frequencies

    Page(s): 125 - 136
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    A precision method for the measurement of the frequency of an oscillating circuit is discussed. The theory on which the method is based is discussed and there is developed an equation which relates the frequency of the beat note between two oscillators to the natural frequency of a circuit which is loosely coupled to one of them. This equation is considered in some detail and certain of its properties are deduced. Curves are drawn for three typical cases. The cause and avoidance of certain errors are considered. The method is extended to the case of a non-oscillating circuit. Finally there is suggested a method for the measurement of small values of mutual inductance. View full abstract»

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  • Precision Determination of Frequency

    Page(s): 137 - 154
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    The relations between frequency and time are such that it is desirable to refer them to a common standard. Reference standards, both of time and of frequency, are characterized by the requirement that their rates shall be so constant that the total number of variations executed in a time of known duration may be taken as a measure of the rate over shorter intervals of time. Frequency standards have the further requirement that the form of their variations and the order of magnitude of their rates shall be suitable for comparison with the waves used in electrical communication. Two different types of standard which meet these requirements are described. One consists of a regenerative vacuum-tube circuit, the frequency of which is determined by the mechanical properties of a tuning fork. The other is a regenerative circuit controlled by a piezo-active crystal. Means are provided, in the case of each standard, whereby the recurrent cycles may be counted by a mechanism having the form of a clock, the rate of which is a measure of the frequency of the reference standard. Data taken over a period of several years with a fork-controlled circuit show that, under normal conditions, its rate may be relied upon to two parts in one million. Data taken over a much shorter time with crystal controlled oscillators indicate that they are about ten times as stable. View full abstract»

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  • A Radio-Frequency Oscillator for Receiver Investigations

    Page(s): 155 - 165
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    A modulated radio-frequency oscillator is described. This apparatus incorporates a means for obtaining radio-frequency outputs of widely varying range, a metering system, a means for changing the generated frequency in small steps to either side of a given frequency, and a modulation and indicating system. View full abstract»

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  • On the Influence of Solar Activity on Radio Transmission

    Page(s): 166 - 173
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    The paper describes further examination of the daylight long wave signal measurements of the Bureau of Standards for evidence of correlation with solar activity. It has already been shown that a probable correlation exists between signals and sunspots when the observations are continued for several years and are averaged in periods of a month or more. The present paper deals especially with observations averaged in shorter (5-day) periods. Here while the relationship is generally evident it is sometimes obscured by an apparent relative phase shift between the signal and sunspot curves. View full abstract»

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  • Ionization in the Upper Atmosphere

    Page(s): 174 - 176
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    First Page of the Article
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  • A Theory of the Upper Atmosphere and Meteors

    Page(s): 177 - 180
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    A calculation of the rate of separation of gases of different density in the earth's atmosphere leads us to expect a uniform mixture of all gases below 100 km and densities of hydrogen and helium roughly a hundred thousandth of those previously calculated, for greater heights. Known absorption and radiation coefficients for gases of the upper atmosphere indicate that we should expect a daily temperature variation of about 140° during the summer and 30° during the winter for all heights greater than 80 km. Carbon dioxide is found to be more effective than water vapor in determining the final escape of radiation from the earth and the conclusion is drawn that variations in the carbon dioxide content of the air may explain the variation in climatic conditions of the earth indicated by the ice ages of the past. Frictional resistance offered by the upper atmosphere to the passage of meteors through it is not sufficient to account for the energy radiated by meteors and the conclusion is reached that the energy of the meteor is probably dissipated into the air by the escape of atoms and molecules driven from the meteor by the energies of impacts with molecules of the air. View full abstract»

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  • A Radio Field Strength Survey of Philadelphia

    Page(s): 181 - 192
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    Measurements of the strength of the electromagnetic waves broadcast by station WFI were taken at representative locations throughout the city of Philadelphia and its environs. In the method used, measurements of the antenna loop resistance were used as a guide in determining when interference was sufficient to cause the rejection of a particular field strength reading. Lines of equal field strength were plotted on a map of the territory; these showed the location of several shadows and of one area in which the field strength was considerably higher than in the surrounding neighborhood. Conditions throughout the city remained virtually unchanged during the two years of the survey, with the exception of a considerable new shadow cast by a large building recently erected near the broadcasting station. View full abstract»

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  • On the Theory of Power Amplification

    Page(s): 193 - 207
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    1. In order to supply a maximum output wattage to an inductive loudspeaker by means of high-power tubes, regardless of the necessary amplitude of Eg, it is necessary to calculate the plate battery and grid-biasing potentials required to ensure distortionless reproduction. 2. From the inductive load on the plate circuit of the tube an elliptical shape of the working characteristic follows, referring to the egiip diagram. 3. If the working ellipse is enclosed by a rectangular quadrangle, the sides of which are parallel to abscissa and ordinate axes respectively, then the slope or angle ops of the diagonal of this quadrangle means the dynamic slope or mutual conductance of the tube for the given plate-circuit load, for 7vpz IV Eg 4. By means of ops and starting from the conditions of distortionless reproduction the position of the diagonal of the quadrangle and its useful part are determined and furthermore the following equations for the minimum necessary plate-battery potential as well as for the necessary grid-biasing potential are found: EB = K+ I3,( rp+ Rb) + IpV( wL) 2+ ( rp + Rbw) 2= Eg * Iu ECCEG-Ip3,/( wL) 2+ ( rp + Rw) 2 5. It is shown what conditions result if several loudspeakers are connected in series or in parallel with each other or if several tubes connected in parallel are employed to supply the loudspeaker. 6. View full abstract»

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  • Condenser Shunt for Measurement of Higi-Frequency Currents of Large Magnitude

    Page(s): 208 - 217
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    The necessity for an accurate ammeter for large high-frequency currents is pointed out. A new device consisting of a large condenser in parallel with a small condenser, and the latter carrying the current to a small thermo-couple ammeter, is described. A device of this nature can be made very accurate; in fact, comparable in accuracy to any available standards. The construction of the device includes provisions for reducing and restricting the electrostatic and electromagnetic field, due to large current, the reduction of distributed inductance and capacity, and a provision to prevent the resonance effect of high harmonics of the operating current. Provisions are also made for locating the measuring instrument at a distance from the circuit. Large ratings are possible by connecting a number of condenser units in parallel. View full abstract»

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  • Book reviews

    Page(s): 218 - 223
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  • Geographical Location of Members Elected January 4, 1928

    Page(s): 224 - 225
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Aims & Scope

This Periodical ceased production in 1938. The current retitled publication is Proceedings of the IEEE.

Full Aims & Scope