Pub Date : 1938-07-01DOI: 10.1109/JRPROC.1938.228385
S.W. Seeley, H. Deal, C. N. Kimball
This paper concerns a new and improved method of remote control which may be applied to electrical devices of any sort. Special attention is given to the exposition of the basic principles of the system as applied to the remote control of radio receivers. The new control arrangement utilizes the alternating-current power line as a medium for transmission of control signals from a remote unit to the controlled device, and is therefore free of the limitations imposed by control cables. The system utilizes a small oscillator, located at the remote point, operating at a frequency between 200 and 400 kilocycles. Use of the 60-cycle line voltage as plate supply causes the radio-frequency output voltage of the remote unit to be modulated in intensity. Control signals are transmitted through the alternating-current power line to the controlled point, where the phase of the 60-cycle line voltage is compared with the phase of the envelope of the radio-frequency control signals in any one of several phase detectors which may be employed for selective purposes. Relays in the detector output circuits are energized and may be made to close power circuits to any desired electrical device. Remote control of the start of operation of an electric appliance may be had without the expenditure of stand-by power in receptive circuits at the controlled point.
{"title":"Teledynamic Control by Selective Ionization with Application to Radio Receivers","authors":"S.W. Seeley, H. Deal, C. N. Kimball","doi":"10.1109/JRPROC.1938.228385","DOIUrl":"https://doi.org/10.1109/JRPROC.1938.228385","url":null,"abstract":"This paper concerns a new and improved method of remote control which may be applied to electrical devices of any sort. Special attention is given to the exposition of the basic principles of the system as applied to the remote control of radio receivers. The new control arrangement utilizes the alternating-current power line as a medium for transmission of control signals from a remote unit to the controlled device, and is therefore free of the limitations imposed by control cables. The system utilizes a small oscillator, located at the remote point, operating at a frequency between 200 and 400 kilocycles. Use of the 60-cycle line voltage as plate supply causes the radio-frequency output voltage of the remote unit to be modulated in intensity. Control signals are transmitted through the alternating-current power line to the controlled point, where the phase of the 60-cycle line voltage is compared with the phase of the envelope of the radio-frequency control signals in any one of several phase detectors which may be employed for selective purposes. Relays in the detector output circuits are energized and may be made to close power circuits to any desired electrical device. Remote control of the start of operation of an electric appliance may be had without the expenditure of stand-by power in receptive circuits at the controlled point.","PeriodicalId":54574,"journal":{"name":"Proceedings of the Institute of Radio Engineers","volume":"26 1","pages":"813-830"},"PeriodicalIF":0.0,"publicationDate":"1938-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1109/JRPROC.1938.228385","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"62307785","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 : 1938-07-01DOI: 10.1109/JRPROC.1938.228424
C. B. Aiken
The current-voltage characteristic of a diode can be expressed at low currents by an equation of the form i = GεkE. An analysis based on this relation shows that the rectification efficiency and input resistance of the usual form of gridleak-condenser diode circuit can be conveniently expressed entirely in terms of the grid-leak resistance R1, the amplitude of the impressed alternating voltage E, a single parameter k of the tube, and an adjustable constant b. k is determined by the cathode temperature, and is constant, for a given tube, as long as the heater voltage is unchanged. b is equal to k times the voltage which exists across R1in the absence of an impressed alternating voltage, and can be adjusted to any value within a wide range by the use of a suitable bias battery. It is shown that large values of b give higher efficiencies of rectification, but that, if b is of the order of 100 or more, the effciency is practically as high as can be obtained, and is nearly independent of b. The various components of alternating current flowing through the diode are given by An= 2A0fn(kE), in which Anis the amplitude of the nth harmonic of the impressed frequency and A0is the direct current through the diode, which last can be separately computed. fn= In(kE)/I0(kE). In(x) is the nth order Bessel's function of a pure imaginary argument.
{"title":"Theory of the Diode Voltmeter","authors":"C. B. Aiken","doi":"10.1109/JRPROC.1938.228424","DOIUrl":"https://doi.org/10.1109/JRPROC.1938.228424","url":null,"abstract":"The current-voltage characteristic of a diode can be expressed at low currents by an equation of the form i = GεkE. An analysis based on this relation shows that the rectification efficiency and input resistance of the usual form of gridleak-condenser diode circuit can be conveniently expressed entirely in terms of the grid-leak resistance R1, the amplitude of the impressed alternating voltage E, a single parameter k of the tube, and an adjustable constant b. k is determined by the cathode temperature, and is constant, for a given tube, as long as the heater voltage is unchanged. b is equal to k times the voltage which exists across R1in the absence of an impressed alternating voltage, and can be adjusted to any value within a wide range by the use of a suitable bias battery. It is shown that large values of b give higher efficiencies of rectification, but that, if b is of the order of 100 or more, the effciency is practically as high as can be obtained, and is nearly independent of b. The various components of alternating current flowing through the diode are given by An= 2A0fn(kE), in which Anis the amplitude of the nth harmonic of the impressed frequency and A0is the direct current through the diode, which last can be separately computed. fn= In(kE)/I0(kE). In(x) is the nth order Bessel's function of a pure imaginary argument.","PeriodicalId":54574,"journal":{"name":"Proceedings of the Institute of Radio Engineers","volume":"26 1","pages":"859-876"},"PeriodicalIF":0.0,"publicationDate":"1938-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1109/JRPROC.1938.228424","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"62308149","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 : 1938-06-01DOI: 10.1109/JRPROC.1938.228332
H. A. Wheeler
Different types of linear rectifiers are defined, and the required properties of linear rectification are outlined. The envelope-type of rectifier is preferred as having greatest efficiency. The ideal diode for this type is defined and its behavior in various circuits is outlined. Formulas are given which enable fairly accurate prediction of performance, especially of such factors as the maximum coefficient of inward modulation which is subject to linear rectification, and the amount of distortion caused by the clipping of the peaks representing unity inward modulation. The formulas indicate desirable relations in terms of the admittance of input and output circuits. It is pointed out that a diode rectifier, under certain conditions, has the effect of shifting along the frequency axis, the admittance curve of the input or output circuit, in a manner similar to the frequency-changing operation on the signal. There are described the effects of practical limitations, such as the departure of the diode from the ideal. Practical examples of circuit design are given.
{"title":"Design Formulas for Diode Detectors","authors":"H. A. Wheeler","doi":"10.1109/JRPROC.1938.228332","DOIUrl":"https://doi.org/10.1109/JRPROC.1938.228332","url":null,"abstract":"Different types of linear rectifiers are defined, and the required properties of linear rectification are outlined. The envelope-type of rectifier is preferred as having greatest efficiency. The ideal diode for this type is defined and its behavior in various circuits is outlined. Formulas are given which enable fairly accurate prediction of performance, especially of such factors as the maximum coefficient of inward modulation which is subject to linear rectification, and the amount of distortion caused by the clipping of the peaks representing unity inward modulation. The formulas indicate desirable relations in terms of the admittance of input and output circuits. It is pointed out that a diode rectifier, under certain conditions, has the effect of shifting along the frequency axis, the admittance curve of the input or output circuit, in a manner similar to the frequency-changing operation on the signal. There are described the effects of practical limitations, such as the departure of the diode from the ideal. Practical examples of circuit design are given.","PeriodicalId":54574,"journal":{"name":"Proceedings of the Institute of Radio Engineers","volume":"26 1","pages":"745-780"},"PeriodicalIF":0.0,"publicationDate":"1938-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1109/JRPROC.1938.228332","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"62308140","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 : 1938-06-01DOI: 10.1109/JRPROC.1938.228331
H. R. Meahl
A jewel-bearing oscillating-ring electrodynamic ammeter is described and the method for calibrating it is explained. Data and calculations are presented to show that it is a standard of current at high frequencies. The frequency characteristics of three miniature thermocouple ammeters are measured with it.
{"title":"A Bearing-Type High-Frequency Electro-Dynamic Ammeter","authors":"H. R. Meahl","doi":"10.1109/JRPROC.1938.228331","DOIUrl":"https://doi.org/10.1109/JRPROC.1938.228331","url":null,"abstract":"A jewel-bearing oscillating-ring electrodynamic ammeter is described and the method for calibrating it is explained. Data and calculations are presented to show that it is a standard of current at high frequencies. The frequency characteristics of three miniature thermocouple ammeters are measured with it.","PeriodicalId":54574,"journal":{"name":"Proceedings of the Institute of Radio Engineers","volume":"26 1","pages":"734-744"},"PeriodicalIF":0.0,"publicationDate":"1938-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1109/JRPROC.1938.228331","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"62308125","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 : 1938-06-01DOI: 10.1109/JRPROC.1938.228214
W. E. Jackson
During the past ten years a large number of instrument landing systems have undergone development and tests and a considerable fund of information has been accumulated concerning the shortcomings and advantages of each. The major airlines of the United States, the Federal Communications Commission, the Bureau of Air Commerce, and the Subcommittee on Instrument Landing Devices of the Radio Technical Committee for Aeronautics have reached an agreement as to the fundamental elements which should be incorporated in a practical instrument landing system and have also outlined a program of projected development. Having this agreement, it is now possible for all interested organizations to proceed with the perfection of a practical system by combining the superior features of the systems which have been tested and to carry on development which will further augment this system. At present, the major airlines are planning to install a number of instrument landing systems, having the fundamental elements agreed upon by the above-mentioned organizations, to be used on an experimental and pilot-training basis. It is recommended that the Bureau of Air Commerce. sponsor further development of instrument landing equipment until it meets the approval of all concerned with regard to operation, reliability, and ease of maintenance as well as fundamental elements. When this condition is reached, it is recommended that the Bureau of Air Commerce purchase, install, and operate a number of these instrument landing systems at various airports throughout the United States on an experimental basis.
{"title":"Status of Instrument Landing Systems","authors":"W. E. Jackson","doi":"10.1109/JRPROC.1938.228214","DOIUrl":"https://doi.org/10.1109/JRPROC.1938.228214","url":null,"abstract":"During the past ten years a large number of instrument landing systems have undergone development and tests and a considerable fund of information has been accumulated concerning the shortcomings and advantages of each. The major airlines of the United States, the Federal Communications Commission, the Bureau of Air Commerce, and the Subcommittee on Instrument Landing Devices of the Radio Technical Committee for Aeronautics have reached an agreement as to the fundamental elements which should be incorporated in a practical instrument landing system and have also outlined a program of projected development. Having this agreement, it is now possible for all interested organizations to proceed with the perfection of a practical system by combining the superior features of the systems which have been tested and to carry on development which will further augment this system. At present, the major airlines are planning to install a number of instrument landing systems, having the fundamental elements agreed upon by the above-mentioned organizations, to be used on an experimental and pilot-training basis. It is recommended that the Bureau of Air Commerce. sponsor further development of instrument landing equipment until it meets the approval of all concerned with regard to operation, reliability, and ease of maintenance as well as fundamental elements. When this condition is reached, it is recommended that the Bureau of Air Commerce purchase, install, and operate a number of these instrument landing systems at various airports throughout the United States on an experimental basis.","PeriodicalId":54574,"journal":{"name":"Proceedings of the Institute of Radio Engineers","volume":"1 1","pages":"681-699"},"PeriodicalIF":0.0,"publicationDate":"1938-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1109/JRPROC.1938.228214","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"62307321","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 : 1938-06-01DOI: 10.1109/JRPROC.1938.228328
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., April 1938","authors":"T. R. Gilliland, S. S. Kirby, N. Smith","doi":"10.1109/JRPROC.1938.228328","DOIUrl":"https://doi.org/10.1109/JRPROC.1938.228328","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":"781-785"},"PeriodicalIF":0.0,"publicationDate":"1938-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1109/JRPROC.1938.228328","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"62308028","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 : 1938-06-01DOI: 10.1109/JRPROC.1938.228330
F. Massa
Horn loud speakers have found widespread commercial application due to their practical possibility of maintaining high efficiency over a relatively wide frequency range. The inherent limitations of such speakers are not generally recognized, however, as neither are the specific relations that must be satisfied in the choice of constants in the electrodynamic system. This paper discusses the limitations of a single speaker to cover the entire range of reproduction. It shows the quantitative relations that must be maintained between the components of the vibrating system in order to secure maximum efficiency at all frequencies. It also demonstrates that certain definite relations must be satisfied if one is to gain by the use of aluminum-wire voice coils. Unless these are satisfied, a loss in efficiency may occur by using aluminum instead of copper. The paper also describes various means that have been employed to avoid the limitations of the single-horn speaker to cover a wide range of reproduction, and concludes with a description of a new experimentally developed speaker employing two entirely separate driving elements mounted on a common magnetic structure; each cone feeding a separate horn. The composite structure takes the approximate form of a cylinder five feet in diameter, two feet deep, and weighs under 100 pounds.
{"title":"Horn-Type Loud Speakers-A Quantitative Discussion of Some Fundamental Requirements in Their Design","authors":"F. Massa","doi":"10.1109/JRPROC.1938.228330","DOIUrl":"https://doi.org/10.1109/JRPROC.1938.228330","url":null,"abstract":"Horn loud speakers have found widespread commercial application due to their practical possibility of maintaining high efficiency over a relatively wide frequency range. The inherent limitations of such speakers are not generally recognized, however, as neither are the specific relations that must be satisfied in the choice of constants in the electrodynamic system. This paper discusses the limitations of a single speaker to cover the entire range of reproduction. It shows the quantitative relations that must be maintained between the components of the vibrating system in order to secure maximum efficiency at all frequencies. It also demonstrates that certain definite relations must be satisfied if one is to gain by the use of aluminum-wire voice coils. Unless these are satisfied, a loss in efficiency may occur by using aluminum instead of copper. The paper also describes various means that have been employed to avoid the limitations of the single-horn speaker to cover a wide range of reproduction, and concludes with a description of a new experimentally developed speaker employing two entirely separate driving elements mounted on a common magnetic structure; each cone feeding a separate horn. The composite structure takes the approximate form of a cylinder five feet in diameter, two feet deep, and weighs under 100 pounds.","PeriodicalId":54574,"journal":{"name":"Proceedings of the Institute of Radio Engineers","volume":"26 1","pages":"720-733"},"PeriodicalIF":0.0,"publicationDate":"1938-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1109/JRPROC.1938.228330","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"62308084","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 : 1938-06-01DOI: 10.1109/JRPROC.1938.228327
J. Sherman
A device is described for automatically showing frequency-response characteristics of audio-frequency apparatus on the screen of a long-persistence cathode-ray tube, without mechanical equipment. This device can be used to trace a curve of output voltage on either linear or logarithmic scale versus frequencies from 20 to 15,000 cycles. The frequency scale can be either logarithmic or take special forms in which desired portions are expanded. Typical results of tests on amplifiers and electroacoustic equipment are presented.
{"title":"An Audio-Frequency-Response Curve Tracer","authors":"J. Sherman","doi":"10.1109/JRPROC.1938.228327","DOIUrl":"https://doi.org/10.1109/JRPROC.1938.228327","url":null,"abstract":"A device is described for automatically showing frequency-response characteristics of audio-frequency apparatus on the screen of a long-persistence cathode-ray tube, without mechanical equipment. This device can be used to trace a curve of output voltage on either linear or logarithmic scale versus frequencies from 20 to 15,000 cycles. The frequency scale can be either logarithmic or take special forms in which desired portions are expanded. Typical results of tests on amplifiers and electroacoustic equipment are presented.","PeriodicalId":54574,"journal":{"name":"Proceedings of the Institute of Radio Engineers","volume":"26 1","pages":"700-712"},"PeriodicalIF":0.0,"publicationDate":"1938-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1109/JRPROC.1938.228327","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"62307987","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 : 1938-06-01DOI: 10.1109/jrproc.1938.228329
J. Potter
This paper describes a new type of sweep circuit for deflecting the electron beam of cathode-ray tubes. The circuit is adaptable for either electrostatic or electromagnetic deflection. Its upper limit of oscillation is approximately 100,000 cycles. The possibility of using the circuit as a multivibrator for generating synchronizing impulses in television is also briefly discussed.
{"title":"Sweep Circuit","authors":"J. Potter","doi":"10.1109/jrproc.1938.228329","DOIUrl":"https://doi.org/10.1109/jrproc.1938.228329","url":null,"abstract":"This paper describes a new type of sweep circuit for deflecting the electron beam of cathode-ray tubes. The circuit is adaptable for either electrostatic or electromagnetic deflection. Its upper limit of oscillation is approximately 100,000 cycles. The possibility of using the circuit as a multivibrator for generating synchronizing impulses in television is also briefly discussed.","PeriodicalId":54574,"journal":{"name":"Proceedings of the Institute of Radio Engineers","volume":"26 1","pages":"713-719"},"PeriodicalIF":0.0,"publicationDate":"1938-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1109/jrproc.1938.228329","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"62308042","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 : 1938-05-01DOI: 10.1109/JRPROC.1938.228325
Julian Blanchard
Fifty years have passed since those memorable researches of the young German physicist, Heinrich Rudolph Hertz, which have come to be regarded as the starting point of radio. For it was he who first detected, and measured, electromagnetic waves in space — waves which had been predicted, it is true, but which had never before been observed. It is not to be claimed, of course, that the radio art would have failed to be born were it not for his genius, for we know that almost simultaneously the experiments of Lodge in England were pointing with certainty to the same discoveries, and the speculations of others were revolving around the possibility of generating electric waves. Yet it was the remarkably clear vision of Hertz, combined with his consummate persistence and skill, that won for him the prize and justly enshrined his name among the immortal men of science.
{"title":"Hertz, The Discoverer of Electric Waves","authors":"Julian Blanchard","doi":"10.1109/JRPROC.1938.228325","DOIUrl":"https://doi.org/10.1109/JRPROC.1938.228325","url":null,"abstract":"Fifty years have passed since those memorable researches of the young German physicist, Heinrich Rudolph Hertz, which have come to be regarded as the starting point of radio. For it was he who first detected, and measured, electromagnetic waves in space — waves which had been predicted, it is true, but which had never before been observed. It is not to be claimed, of course, that the radio art would have failed to be born were it not for his genius, for we know that almost simultaneously the experiments of Lodge in England were pointing with certainty to the same discoveries, and the speculations of others were revolving around the possibility of generating electric waves. Yet it was the remarkably clear vision of Hertz, combined with his consummate persistence and skill, that won for him the prize and justly enshrined his name among the immortal men of science.","PeriodicalId":54574,"journal":{"name":"Proceedings of the Institute of Radio Engineers","volume":"26 1","pages":"505-515"},"PeriodicalIF":0.0,"publicationDate":"1938-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1109/JRPROC.1938.228325","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"62307272","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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