Pub Date : 1938-11-01DOI: 10.1109/JRPROC.1938.228829
T. R. Gilliland, S. S. Kirby, N. Smith
Data on the ordinary-wave critical frequencies and virtual heights of the ionospheric layers are presented for the period indicated in the title. The monthly average values of the maximum usable frequencies for undisturbed days, for radio transmission by way of the regular layers is also provided.
{"title":"Characteristics of the Ionosphere at Washington, D.C., September, 1938","authors":"T. R. Gilliland, S. S. Kirby, N. Smith","doi":"10.1109/JRPROC.1938.228829","DOIUrl":"https://doi.org/10.1109/JRPROC.1938.228829","url":null,"abstract":"Data on the ordinary-wave critical frequencies and virtual heights of the ionospheric layers are presented for the period indicated in the title. The monthly average values of the maximum usable frequencies for undisturbed days, for radio transmission by way of the regular layers is also provided.","PeriodicalId":54574,"journal":{"name":"Proceedings of the Institute of Radio Engineers","volume":"26 1","pages":"1408-1410"},"PeriodicalIF":0.0,"publicationDate":"1938-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1109/JRPROC.1938.228829","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"62308414","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1938-11-01DOI: 10.1109/JRPROC.1938.228742
J.E. Smith, F.H. Kroger, R. George
The utilization of an ultra-high-frequency radio circuit for the transmission of telegraph, teletype printer, and facsimile signals is described. The operating procedure is stressed throughout, particularly with regard to equipment maintenance tests and the methods employed to determine the conditions of the circuit such as degree of modulation, signal-to-noise ratio, etc. Considerations are presented with respect to the most efficient division of the total modulation band into the communication channels, as well as the signal-to-noise ratios required for the different types of service. It is found that fading, static, and weather conditions at these frequencies are of little importance as to their effect on the economic use of the circuit. However, diathermy machines and similar sources of disturbance are troublesome and their effect must be minimized. Experience during the past year and a half indicates that the dependability of the ultra-high-frequency radio circuit is of a high order.
{"title":"Practical Application of an Ultra-High-Frequency Radio-Relay Circuit","authors":"J.E. Smith, F.H. Kroger, R. George","doi":"10.1109/JRPROC.1938.228742","DOIUrl":"https://doi.org/10.1109/JRPROC.1938.228742","url":null,"abstract":"The utilization of an ultra-high-frequency radio circuit for the transmission of telegraph, teletype printer, and facsimile signals is described. The operating procedure is stressed throughout, particularly with regard to equipment maintenance tests and the methods employed to determine the conditions of the circuit such as degree of modulation, signal-to-noise ratio, etc. Considerations are presented with respect to the most efficient division of the total modulation band into the communication channels, as well as the signal-to-noise ratios required for the different types of service. It is found that fading, static, and weather conditions at these frequencies are of little importance as to their effect on the economic use of the circuit. However, diathermy machines and similar sources of disturbance are troublesome and their effect must be minimized. Experience during the past year and a half indicates that the dependability of the ultra-high-frequency radio circuit is of a high order.","PeriodicalId":54574,"journal":{"name":"Proceedings of the Institute of Radio Engineers","volume":"26 1","pages":"1311-1326"},"PeriodicalIF":0.0,"publicationDate":"1938-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1109/JRPROC.1938.228742","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"62308655","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1938-11-01DOI: 10.1109/JRPROC.1938.228783
Keikitiro Tani, Y. Ito, H. Sinkawa
The long-period variations in the F2region are discussed with data based on observations of the ionosphere for the last 42 months since May, 1934, by the Naval Technical Research Department, Tokyo. The variations in the critical frequency of the penetration are presented in the form of monthly averages of the noon values. The mtean values of the hourly critical frequencies of the penetration for a month were calculated in order to measure the approximate value of the energy absorbed by the F2region. It is shown that these mean values change with the zenith angle of the sun, and they seem to have similar characteristics in both hemispheres. The rate of the seasonal variation in these values, moreover, is much greater in the southern hemisphere than in the northern hemisphere. From this it is presumed that there are two kinds of variations in the energy absorbed by the F2region, the one seasonal and the other annual, the effect of these variations being differential in the northern hemisphere and additional in the southern hemisphere. The anomalous variation in the critical frequency of the F2region may be explained by this presumption with the aid of the hypothesis of thermal expansion. A graph of the seasonal variations in the minimum virtual height is given, in which it is shown that this variation seems to prove the foregoing presumptions.
{"title":"On the Long-Period Variations in the F2Region of the Ionosphere","authors":"Keikitiro Tani, Y. Ito, H. Sinkawa","doi":"10.1109/JRPROC.1938.228783","DOIUrl":"https://doi.org/10.1109/JRPROC.1938.228783","url":null,"abstract":"The long-period variations in the F2region are discussed with data based on observations of the ionosphere for the last 42 months since May, 1934, by the Naval Technical Research Department, Tokyo. The variations in the critical frequency of the penetration are presented in the form of monthly averages of the noon values. The mtean values of the hourly critical frequencies of the penetration for a month were calculated in order to measure the approximate value of the energy absorbed by the F2region. It is shown that these mean values change with the zenith angle of the sun, and they seem to have similar characteristics in both hemispheres. The rate of the seasonal variation in these values, moreover, is much greater in the southern hemisphere than in the northern hemisphere. From this it is presumed that there are two kinds of variations in the energy absorbed by the F2region, the one seasonal and the other annual, the effect of these variations being differential in the northern hemisphere and additional in the southern hemisphere. The anomalous variation in the critical frequency of the F2region may be explained by this presumption with the aid of the hypothesis of thermal expansion. A graph of the seasonal variations in the minimum virtual height is given, in which it is shown that this variation seems to prove the foregoing presumptions.","PeriodicalId":54574,"journal":{"name":"Proceedings of the Institute of Radio Engineers","volume":"76 1","pages":"1340-1346"},"PeriodicalIF":0.0,"publicationDate":"1938-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1109/JRPROC.1938.228783","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"62308272","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1938-10-01DOI: 10.1109/JRPROC.1938.228727
T. R. Gilliland, S. S. Kirby, N. Smith
Data on the ordinary-wave critical frequencies and virtual heights of the ionospheric layers are presented for the period indicated in the title. The monthly average values of the maximum usable frequencies for undisturbed days, for radio transmission by way of the regular layers is also provided.
{"title":"Characteristics of the Ionosphere at Washington, D.C., August, 1938","authors":"T. R. Gilliland, S. S. Kirby, N. Smith","doi":"10.1109/JRPROC.1938.228727","DOIUrl":"https://doi.org/10.1109/JRPROC.1938.228727","url":null,"abstract":"Data on the ordinary-wave critical frequencies and virtual heights of the ionospheric layers are presented for the period indicated in the title. The monthly average values of the maximum usable frequencies for undisturbed days, for radio transmission by way of the regular layers is also provided.","PeriodicalId":54574,"journal":{"name":"Proceedings of the Institute of Radio Engineers","volume":"53 1","pages":"1295-1298"},"PeriodicalIF":0.0,"publicationDate":"1938-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1109/JRPROC.1938.228727","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"62308584","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1938-10-01DOI: 10.1109/JRPROC.1938.228725
L. A. Meacham
A new type of constant-frequency oscillator of very high stability is presented. The frequency-controlling resonant element is used as one arm of a Wheatstone resistance bridge. Kept in balance automatically by a thermally controlled arm, this bridge provides constancy of output amplitude, purity of wave form, and stabilization against fluctuations in power supply or changes in circuit elements. A simple one-tube circuit has operated consistently with no short-time frequency variations greater than ± 2 parts in 108. Convenient means are provided for making precision adjustments over a narrow range of frequencies to compensate for longtime aging effects. Description of the circuit is followed by a brief linear analysis and an account of experimental results. Operating records are given for a 100-kilocycle oscillator.
{"title":"The Bridge-Stabilized Oscillator","authors":"L. A. Meacham","doi":"10.1109/JRPROC.1938.228725","DOIUrl":"https://doi.org/10.1109/JRPROC.1938.228725","url":null,"abstract":"A new type of constant-frequency oscillator of very high stability is presented. The frequency-controlling resonant element is used as one arm of a Wheatstone resistance bridge. Kept in balance automatically by a thermally controlled arm, this bridge provides constancy of output amplitude, purity of wave form, and stabilization against fluctuations in power supply or changes in circuit elements. A simple one-tube circuit has operated consistently with no short-time frequency variations greater than ± 2 parts in 108. Convenient means are provided for making precision adjustments over a narrow range of frequencies to compensate for longtime aging effects. Description of the circuit is followed by a brief linear analysis and an account of experimental results. Operating records are given for a 100-kilocycle oscillator.","PeriodicalId":54574,"journal":{"name":"Proceedings of the Institute of Radio Engineers","volume":"37 1","pages":"1278-1294"},"PeriodicalIF":0.0,"publicationDate":"1938-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1109/JRPROC.1938.228725","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"62308568","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1938-10-01DOI: 10.1109/JRPROC.1938.228724
W. Chu, Chung-Kwei Chang
Formulas are derived for the solution of the transient receiving-end currents of resistance-terminated dissipative T- and π-type low-pass and high-pass electric wave filters. Oscillograms taken with a cathode-ray oscillograph for direct- and alternating-current cases are found to agree with the results calculated from these formulas. From these calculations the following conclusions are derived: (1) When the terminating resistance is gradually increased from zero, the damping constants of the damped sine terms begin to differ greatly from each other, ranging in decreasing amplitudes from the first damped sine term to the last term of (approximately) cutoff frequency. Hence, the transient is ultimately of the cutoff frequency. At the last frequency, this constant is greater than the corresponding constant (approximately equal to R/2L), when the termination is absent. (2) For each increase of one section, there is introduced an additional damped sine term with a smaller damping constant. Therefore transients die out faster in filters of a small number of sections. (3) The last resonant frequency of the filters varies with the number of sections used. It approaches the cutoff frequency as the number of sections is increased. This paper deals with the receiving-end transient currents of resistance-terminated dissipative low-pass and high-pass electric wave filters of T- and π-types. Transients of nondissipative electric wave filters were first treated by John R. Carson and Otto J. Zobel, who considered primarily an infinite succession of similar T sections and obtained formulas for the current at any section. In 1935, E. Weber and M. J.
推导了电阻端耗散型T型和π型低通和高通滤波器接收端瞬态电流的求解公式。用阴极射线示波器在直流电和交流电情况下所作的示波图与这些公式计算的结果一致。从这些计算中得出以下结论:(1)当终止电阻从零逐渐增加时，阻尼正弦项的阻尼常数开始彼此差异很大，从第一个阻尼正弦项到(近似)截止频率的最后一项的幅度减小。因此，暂态最终是截止频率。在最后一个频率，当没有终止时，该常数大于相应的常数(近似等于R/2L)。(2)对于每增加一个截面，引入一个附加的阻尼正弦项，其阻尼常数较小。因此，在少数部分的滤波器中，瞬态消失得更快。(3)滤波器的最后谐振频率随所使用的截面数而变化。随着截面数的增加，它接近截止频率。本文研究了T型和π型电阻端耗散低通和高通滤波器的接收端瞬态电流。John R. Carson和Otto J. Zobel首先处理了非耗散波滤波器的瞬态，他们主要考虑了相似T截面的无限连续，并得到了任意截面上电流的公式。1935年，E.韦伯和M. J。
{"title":"Transients of Resistance-Terminated Dissipative Low-Pass and High-Pass Electric Wave Filters","authors":"W. Chu, Chung-Kwei Chang","doi":"10.1109/JRPROC.1938.228724","DOIUrl":"https://doi.org/10.1109/JRPROC.1938.228724","url":null,"abstract":"Formulas are derived for the solution of the transient receiving-end currents of resistance-terminated dissipative T- and π-type low-pass and high-pass electric wave filters. Oscillograms taken with a cathode-ray oscillograph for direct- and alternating-current cases are found to agree with the results calculated from these formulas. From these calculations the following conclusions are derived: (1) When the terminating resistance is gradually increased from zero, the damping constants of the damped sine terms begin to differ greatly from each other, ranging in decreasing amplitudes from the first damped sine term to the last term of (approximately) cutoff frequency. Hence, the transient is ultimately of the cutoff frequency. At the last frequency, this constant is greater than the corresponding constant (approximately equal to R/2L), when the termination is absent. (2) For each increase of one section, there is introduced an additional damped sine term with a smaller damping constant. Therefore transients die out faster in filters of a small number of sections. (3) The last resonant frequency of the filters varies with the number of sections used. It approaches the cutoff frequency as the number of sections is increased. This paper deals with the receiving-end transient currents of resistance-terminated dissipative low-pass and high-pass electric wave filters of T- and π-types. Transients of nondissipative electric wave filters were first treated by John R. Carson and Otto J. Zobel, who considered primarily an infinite succession of similar T sections and obtained formulas for the current at any section. In 1935, E. Weber and M. J.","PeriodicalId":54574,"journal":{"name":"Proceedings of the Institute of Radio Engineers","volume":"26 1","pages":"1266-1277"},"PeriodicalIF":0.0,"publicationDate":"1938-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1109/JRPROC.1938.228724","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"62308500","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1938-09-01DOI: 10.1109/JRPROC.1938.228561
P. P. Eckersley
An economy in the frequency-channel width occupied by stations sending telephony signals can be made by removing one sideband from the transmitted spectrum. This operation however produces a distortion of the received signals which can only be minimized by an intensification of the carrier component compared with the side-band component. If this intensification is performed at the transmitter the carrier power must be enormously increased and the scheme would be impracticably uneconomic; it is furthermore impossible in broadcast technology to make the necessary alterations to intensify the carrier component in existing receivers all at once because they are publicly owned and extremely numerous. The distortion produced in the absence of carrier-wave intensification at either transmitter or receiver is mainly directly proportional to modulation. The modulation demanded in the transmission of ordinary speech and music is much less at the higher frequencies of modulation than that taking place in the lower middle frequencies. In order, therefore, to approach the ideal of the carrier- and single-side-band system, circuits have been devised to produce what is called an asymmetric side-band transmission in which only the outer parts of the side band are cut away.
{"title":"Asymmetric-Side-Band Broadcasting","authors":"P. P. Eckersley","doi":"10.1109/JRPROC.1938.228561","DOIUrl":"https://doi.org/10.1109/JRPROC.1938.228561","url":null,"abstract":"An economy in the frequency-channel width occupied by stations sending telephony signals can be made by removing one sideband from the transmitted spectrum. This operation however produces a distortion of the received signals which can only be minimized by an intensification of the carrier component compared with the side-band component. If this intensification is performed at the transmitter the carrier power must be enormously increased and the scheme would be impracticably uneconomic; it is furthermore impossible in broadcast technology to make the necessary alterations to intensify the carrier component in existing receivers all at once because they are publicly owned and extremely numerous. The distortion produced in the absence of carrier-wave intensification at either transmitter or receiver is mainly directly proportional to modulation. The modulation demanded in the transmission of ordinary speech and music is much less at the higher frequencies of modulation than that taking place in the lower middle frequencies. In order, therefore, to approach the ideal of the carrier- and single-side-band system, circuits have been devised to produce what is called an asymmetric side-band transmission in which only the outer parts of the side band are cut away.","PeriodicalId":54574,"journal":{"name":"Proceedings of the Institute of Radio Engineers","volume":"26 1","pages":"1041-1092"},"PeriodicalIF":0.0,"publicationDate":"1938-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1109/JRPROC.1938.228561","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"62308615","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1938-09-01DOI: 10.1109/JRPROC.1938.228563
T. R. Gilliland, S. S. Kirby, N. Smith
Data on the ordinary-wave critical frequencies and virtual heights of the ionospheric layers are presented for the period indicated in the title. The monthly average values of the maximum usable frequencies for undisturbed days, for radio transmission by way of the regular layers is also provided.
{"title":"Characteristics of the Ionosphere at Washington, D.C., July, 1938","authors":"T. R. Gilliland, S. S. Kirby, N. Smith","doi":"10.1109/JRPROC.1938.228563","DOIUrl":"https://doi.org/10.1109/JRPROC.1938.228563","url":null,"abstract":"Data on the ordinary-wave critical frequencies and virtual heights of the ionospheric layers are presented for the period indicated in the title. The monthly average values of the maximum usable frequencies for undisturbed days, for radio transmission by way of the regular layers is also provided.","PeriodicalId":54574,"journal":{"name":"Proceedings of the Institute of Radio Engineers","volume":"26 1","pages":"1171-1174"},"PeriodicalIF":0.0,"publicationDate":"1938-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1109/JRPROC.1938.228563","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"62308680","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1938-09-01DOI: 10.1109/JRPROC.1938.228562
W. E. Benham
A formula adapting Maxwell's solution for a plane grating to the plane triode differs from those obtained by previous workers. The triode is simulated by a diode whose electrode separation exceeds the cathode-grid clearance by an amount which is calculated from electrostatic considerations. Corresponding results are derived for the cylindrical triode by means of conformal representation, and are shown to agree better with experiment than the formulas of King and of van der Bijl. The nonuniformity of the electric field due to the presence of the grid, "grating effect," is not marked at the cathode surface, as generally supposed, the field at the cathode being sensibly uniform along the length of the cathode even for grids for which the distance between wires is equal to the cathode-grid clearance. This result is obtained directly from Maxwell's treatise. As the electrons approach the grid the nonuniformity then becomes important and the space-current stream is subject to electron optical considerations. These cause the known departures of gmfrom theory in openmesh tubes. The effects of space charge on the measured amplification factor are briefly discussed. It is shown that μ is two stages removed from the Maxwell shielding constant μ0. The importance of the cathode-plate capacitance is mentioned and an expression given for its approximate value under operating conditions.
将平面光栅的麦克斯韦解应用于平面三极管的公式与前人所得的公式有所不同。该三极管由一个二极管模拟，其电极间距超过阴极-栅极间隙的量是根据静电因素计算的。用保角表示的方法对圆柱三极管得到了相应的结果，与King和van der Bijl的公式相比，与实验结果更吻合。由于栅极的存在而引起的电场的不均匀性，即“光栅效应”，在阴极表面并没有被标记出来，正如通常所设想的那样，阴极上的电场沿着阴极的长度是均匀的，即使对于导线之间的距离等于阴极-栅极间隙的栅极来说也是如此。这个结果是直接从麦克斯韦的论文中得出的。当电子靠近栅格时，不均匀性就变得很重要，并且空间电流受到电子光学的考虑。这些导致已知的gmv在开孔管中偏离理论。简要讨论了空间电荷对测量放大系数的影响。结果表明，μ与麦克斯韦屏蔽常数μ0相差两级。文中提到了阴极极板电容的重要性，并给出了其在工作条件下的近似值的表达式。
{"title":"A Contribution to Tube and Amplifier Theory","authors":"W. E. Benham","doi":"10.1109/JRPROC.1938.228562","DOIUrl":"https://doi.org/10.1109/JRPROC.1938.228562","url":null,"abstract":"A formula adapting Maxwell's solution for a plane grating to the plane triode differs from those obtained by previous workers. The triode is simulated by a diode whose electrode separation exceeds the cathode-grid clearance by an amount which is calculated from electrostatic considerations. Corresponding results are derived for the cylindrical triode by means of conformal representation, and are shown to agree better with experiment than the formulas of King and of van der Bijl. The nonuniformity of the electric field due to the presence of the grid, \"grating effect,\" is not marked at the cathode surface, as generally supposed, the field at the cathode being sensibly uniform along the length of the cathode even for grids for which the distance between wires is equal to the cathode-grid clearance. This result is obtained directly from Maxwell's treatise. As the electrons approach the grid the nonuniformity then becomes important and the space-current stream is subject to electron optical considerations. These cause the known departures of gmfrom theory in openmesh tubes. The effects of space charge on the measured amplification factor are briefly discussed. It is shown that μ is two stages removed from the Maxwell shielding constant μ0. The importance of the cathode-plate capacitance is mentioned and an expression given for its approximate value under operating conditions.","PeriodicalId":54574,"journal":{"name":"Proceedings of the Institute of Radio Engineers","volume":"26 1","pages":"1093-1170"},"PeriodicalIF":0.0,"publicationDate":"1938-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1109/JRPROC.1938.228562","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"62308628","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1938-08-01DOI: 10.1109/JRPROC.1938.228493
W. N. Parker
Present-day high-fidelity 441-line television demands modulation frequencies as high as 4 megacycles. Tube capacitance and the flywheel effect of resonant circuits make such modulation difficult and inefficient when conventional methods are used. The author describes a system called "transmission-line modulation" in which modulation is effected between the radio-frequency generator and the antenna by means of a variable impedance connected across the radio-frequency transmission line. This impedance, consisting of a quarter-wave line terminating in the modulator tubes, is controlled by the voltage applied to the grids of these tubes. At high video frequencies the plate efficiency and degree of modulation compare favorably with the conventional systems employed in sound broadcasting. A 1-kilowatt experimental television transmitter employing this system, which may be modulated 80 per cent at frequencies up to 5 megacycles, is described. For demonstration purposes a 200-megacycle oscillator, modulated at frequencies up to 20 megacycles, is shown.
{"title":"A Unique Method of Modulation for High-Fidelity Television Transmitters","authors":"W. N. Parker","doi":"10.1109/JRPROC.1938.228493","DOIUrl":"https://doi.org/10.1109/JRPROC.1938.228493","url":null,"abstract":"Present-day high-fidelity 441-line television demands modulation frequencies as high as 4 megacycles. Tube capacitance and the flywheel effect of resonant circuits make such modulation difficult and inefficient when conventional methods are used. The author describes a system called \"transmission-line modulation\" in which modulation is effected between the radio-frequency generator and the antenna by means of a variable impedance connected across the radio-frequency transmission line. This impedance, consisting of a quarter-wave line terminating in the modulator tubes, is controlled by the voltage applied to the grids of these tubes. At high video frequencies the plate efficiency and degree of modulation compare favorably with the conventional systems employed in sound broadcasting. A 1-kilowatt experimental television transmitter employing this system, which may be modulated 80 per cent at frequencies up to 5 megacycles, is described. For demonstration purposes a 200-megacycle oscillator, modulated at frequencies up to 20 megacycles, is shown.","PeriodicalId":54574,"journal":{"name":"Proceedings of the Institute of Radio Engineers","volume":"26 1","pages":"946-962"},"PeriodicalIF":0.0,"publicationDate":"1938-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1109/JRPROC.1938.228493","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"62307821","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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