Pub Date : 1962-07-01DOI: 10.1109/JRPROC.1962.288156
G. W. Jull, D. Doyle, G. Irvine, J. Murray
This paper presents evidence that systematic oblique incidence channel sampling transmissions are valuable for improving the reliability of air-ground HF communications when propagation conditions are marginal. This evidence results from air-ground radio communications trials supplemented by frequency sounding transmissions over flight paths of up to 1260 nautical miles into auroral zone latitudes from a ground station in Nova Scotia. The ground-air frequency sounding measurements established that propagation via clouds of auroral sporadic E was possible for a high percentage of time during geomagnetic storms. These modes provided a useful, and often the only, mode for communications over the air-ground path. In order to communicate effectively via auroral E modes, it was found necessary to use a wide selection of aeronautical frequencies. In addition, because of the rapid variation in HF propagation conditions, it was found desirable to renew channel sampling measurements once every five minutes on each frequency assignment. It was established that this procedure for the selection of operating frequencies during disturbances resulted in communications reliability that was appreciably higher than would have been obtained if other frequency selection techniques, alone, were followed.
{"title":"Frequency Sounding Techniques for HF Communications over Auroral Zone Paths","authors":"G. W. Jull, D. Doyle, G. Irvine, J. Murray","doi":"10.1109/JRPROC.1962.288156","DOIUrl":"https://doi.org/10.1109/JRPROC.1962.288156","url":null,"abstract":"This paper presents evidence that systematic oblique incidence channel sampling transmissions are valuable for improving the reliability of air-ground HF communications when propagation conditions are marginal. This evidence results from air-ground radio communications trials supplemented by frequency sounding transmissions over flight paths of up to 1260 nautical miles into auroral zone latitudes from a ground station in Nova Scotia. The ground-air frequency sounding measurements established that propagation via clouds of auroral sporadic E was possible for a high percentage of time during geomagnetic storms. These modes provided a useful, and often the only, mode for communications over the air-ground path. In order to communicate effectively via auroral E modes, it was found necessary to use a wide selection of aeronautical frequencies. In addition, because of the rapid variation in HF propagation conditions, it was found desirable to renew channel sampling measurements once every five minutes on each frequency assignment. It was established that this procedure for the selection of operating frequencies during disturbances resulted in communications reliability that was appreciably higher than would have been obtained if other frequency selection techniques, alone, were followed.","PeriodicalId":20574,"journal":{"name":"Proceedings of the IRE","volume":"25 1","pages":"1676-1682"},"PeriodicalIF":0.0,"publicationDate":"1962-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73043314","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 : 1962-07-01DOI: 10.1109/JRPROC.1962.288130
H. Heffner
If the uncertainty principle of quantum mechanics is applied to the process of signal measurement, two theorems relating to amplifier noise performance can be deduced. First, it can be shown that it is impossible to construct a linear noiseless amplifier. Second, if the amplifier is characterized as having additive white Gaussian noise, it can be shown that the minimum possible noise temperature of any linear amplifier is T.= In 2 -IIG -hv 1-1/ IG k In the limit of high gain G this expression reduces to that previously derived for the ideal maser and parametric amplifier. It is shown that the minimum noise amplifier does not degrade the signal but rather allows the use of an inaccurate detector to make measurements on an incoming signal to the greatest accuracy consistent with the uncertainty principle.
{"title":"The Fundamental Noise Limit of Linear Amplifiers","authors":"H. Heffner","doi":"10.1109/JRPROC.1962.288130","DOIUrl":"https://doi.org/10.1109/JRPROC.1962.288130","url":null,"abstract":"If the uncertainty principle of quantum mechanics is applied to the process of signal measurement, two theorems relating to amplifier noise performance can be deduced. First, it can be shown that it is impossible to construct a linear noiseless amplifier. Second, if the amplifier is characterized as having additive white Gaussian noise, it can be shown that the minimum possible noise temperature of any linear amplifier is T.= In 2 -IIG -hv 1-1/ IG k In the limit of high gain G this expression reduces to that previously derived for the ideal maser and parametric amplifier. It is shown that the minimum noise amplifier does not degrade the signal but rather allows the use of an inaccurate detector to make measurements on an incoming signal to the greatest accuracy consistent with the uncertainty principle.","PeriodicalId":20574,"journal":{"name":"Proceedings of the IRE","volume":"2 1","pages":"1604-1608"},"PeriodicalIF":0.0,"publicationDate":"1962-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78471804","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 : 1962-07-01DOI: 10.1109/JRPROC.1962.288154
L. Malling
Highly phase-stable, crystal-controlled oscillators are playing an increasingly important role in extending the range of deep-space communications. For example, during a recent radar experiment with the planet Venus, then at a range of 35-million miles, real-time detection was accomplished with a receiver bandwidth of 5 cps and a search frequency of 2388 Mc. Spectral measurements of the Venus-reflected signal indicated at times a spectrum of only a few cycles in width. The ability to resolve such narrow phenomena was gained through the use of extremely phase-stable oscillators combined with extremely precise predicted control of the frequency of the receiver local oscillator. The purpose here is to discuss oscillator phase noise, its origin, and techniques for its observation and measurement. Relationship between the phase noise, the spectrum, the short-term stability, and the Q of the oscillator is established.
{"title":"Phase-Stable Oscillators for Space Communications, including the Relationship between the Phase Noise, the Spectrum, the Short-Term Stability, and the Q of the Oscillator","authors":"L. Malling","doi":"10.1109/JRPROC.1962.288154","DOIUrl":"https://doi.org/10.1109/JRPROC.1962.288154","url":null,"abstract":"Highly phase-stable, crystal-controlled oscillators are playing an increasingly important role in extending the range of deep-space communications. For example, during a recent radar experiment with the planet Venus, then at a range of 35-million miles, real-time detection was accomplished with a receiver bandwidth of 5 cps and a search frequency of 2388 Mc. Spectral measurements of the Venus-reflected signal indicated at times a spectrum of only a few cycles in width. The ability to resolve such narrow phenomena was gained through the use of extremely phase-stable oscillators combined with extremely precise predicted control of the frequency of the receiver local oscillator. The purpose here is to discuss oscillator phase noise, its origin, and techniques for its observation and measurement. Relationship between the phase noise, the spectrum, the short-term stability, and the Q of the oscillator is established.","PeriodicalId":20574,"journal":{"name":"Proceedings of the IRE","volume":"17 1","pages":"1656-1664"},"PeriodicalIF":0.0,"publicationDate":"1962-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84425321","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 : 1962-07-01DOI: 10.1109/JRPROC.1962.288153
C. Renton, B. Rabinovici
When a number of negative resistance elements are interconnected, a multistable voltage-current characteristic will be generated. The form of this composite characteristic will depend on the mode of interconnection and on the characteristics of the individual elements. 2n stable states can be generated using n negative resistance elements when the individual characteristics of the elements obey certain rules derived herein. A modified flip-flop circuit has been developed whose characteristic can be precisely tailored to fulfill the requirements. Several applications to logical functions are discussed. Potential advantages of this method lie in the circuit simplicity resulting from an intrinsic feedback operation which replaces separate logical functions.
{"title":"Composite Characteristics of Negative Resistance Devices and Their Application in Digital Circults","authors":"C. Renton, B. Rabinovici","doi":"10.1109/JRPROC.1962.288153","DOIUrl":"https://doi.org/10.1109/JRPROC.1962.288153","url":null,"abstract":"When a number of negative resistance elements are interconnected, a multistable voltage-current characteristic will be generated. The form of this composite characteristic will depend on the mode of interconnection and on the characteristics of the individual elements. 2n stable states can be generated using n negative resistance elements when the individual characteristics of the elements obey certain rules derived herein. A modified flip-flop circuit has been developed whose characteristic can be precisely tailored to fulfill the requirements. Several applications to logical functions are discussed. Potential advantages of this method lie in the circuit simplicity resulting from an intrinsic feedback operation which replaces separate logical functions.","PeriodicalId":20574,"journal":{"name":"Proceedings of the IRE","volume":"22 1","pages":"1648-1656"},"PeriodicalIF":0.0,"publicationDate":"1962-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86055744","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 : 1962-07-01DOI: 10.1109/JRPROC.1962.288150
R. Kyhl, R. McFarlane, M. W. P. Strandberg
The analysis of solid-state cavity masers is extended to include the reactive component of the paramagnetic resonance. This reactance is inverted (in opposition to Foster's reactance theorem). A two-cavity network makes use of this negative frequency dependence of reactance to obtain a broad-band flat-topped amplifier response. In verification of this theory a ruby maser has been built which has a 95-Mc bandwidth at 14-db gain and operates at 9000 Mc and 1.5°K. This performance is comparable to that of published, tapered magnetic field traveling-wave masers. General network limitations on cavity maser amplifiers are derived. Broadbanding techniques that have been published for parametric amplifiers are essentially equivalent. The tuning of the broad-band amplifier is critical. The same performance can be achieved in a unilateral transmission maser by using circularly polarized cavities, but the problem of circuit design and tuning with the increased number of parameters has thus far prevented successful operation.
{"title":"Negative L and C in Solid-State Masers","authors":"R. Kyhl, R. McFarlane, M. W. P. Strandberg","doi":"10.1109/JRPROC.1962.288150","DOIUrl":"https://doi.org/10.1109/JRPROC.1962.288150","url":null,"abstract":"The analysis of solid-state cavity masers is extended to include the reactive component of the paramagnetic resonance. This reactance is inverted (in opposition to Foster's reactance theorem). A two-cavity network makes use of this negative frequency dependence of reactance to obtain a broad-band flat-topped amplifier response. In verification of this theory a ruby maser has been built which has a 95-Mc bandwidth at 14-db gain and operates at 9000 Mc and 1.5°K. This performance is comparable to that of published, tapered magnetic field traveling-wave masers. General network limitations on cavity maser amplifiers are derived. Broadbanding techniques that have been published for parametric amplifiers are essentially equivalent. The tuning of the broad-band amplifier is critical. The same performance can be achieved in a unilateral transmission maser by using circularly polarized cavities, but the problem of circuit design and tuning with the increased number of parameters has thus far prevented successful operation.","PeriodicalId":20574,"journal":{"name":"Proceedings of the IRE","volume":"45 1","pages":"1608-1623"},"PeriodicalIF":0.0,"publicationDate":"1962-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74428438","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 : 1962-07-01DOI: 10.1109/JRPROC.1962.288152
J. Wait
This paper is a self-contained exposition of the conventional theory of propagation of VLF radio waves. The model is a spherical earth surrounded by a concentric ionosphere. Although the model is highly idealized, the theory is still quite involved. The complexities arise from the long wavelengths inherent in such problems. In Section I the elementary geometrical or hop theory for VLF is considered. This includes a discussion of ionospheric reflection coefficients and the influence of multiple reflections. The validity of the model is established by a comparison with experimental data. In Section II, the diffractive corrections near the caustics of the ray systems are obtained. These provide a means to extend the theory to points near and beyond the horizon point for the individual hops or rays. In Section III, the waveguide mode theory is expounded. A number of approximations and simplifications are introduced in order to illustrate principles. References to more detailed analyses which use higher order approximations are given. Finally, in Section IV, the influence of a stratified ionosphere is treated by using a two-layer model. The material in this paper was included in the Summer (1961) Lecture Course on Radio Propagation given at the Boulder Laboratories of the National Bureau of Standards, and in earlier graduate courses, at the University of Colorado.
{"title":"Introduction to the Theory of VLF Propagation","authors":"J. Wait","doi":"10.1109/JRPROC.1962.288152","DOIUrl":"https://doi.org/10.1109/JRPROC.1962.288152","url":null,"abstract":"This paper is a self-contained exposition of the conventional theory of propagation of VLF radio waves. The model is a spherical earth surrounded by a concentric ionosphere. Although the model is highly idealized, the theory is still quite involved. The complexities arise from the long wavelengths inherent in such problems. In Section I the elementary geometrical or hop theory for VLF is considered. This includes a discussion of ionospheric reflection coefficients and the influence of multiple reflections. The validity of the model is established by a comparison with experimental data. In Section II, the diffractive corrections near the caustics of the ray systems are obtained. These provide a means to extend the theory to points near and beyond the horizon point for the individual hops or rays. In Section III, the waveguide mode theory is expounded. A number of approximations and simplifications are introduced in order to illustrate principles. References to more detailed analyses which use higher order approximations are given. Finally, in Section IV, the influence of a stratified ionosphere is treated by using a two-layer model. The material in this paper was included in the Summer (1961) Lecture Course on Radio Propagation given at the Boulder Laboratories of the National Bureau of Standards, and in earlier graduate courses, at the University of Colorado.","PeriodicalId":20574,"journal":{"name":"Proceedings of the IRE","volume":"6 1","pages":"1624-1647"},"PeriodicalIF":0.0,"publicationDate":"1962-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84745004","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 : 1962-07-01DOI: 10.1109/JRPROC.1962.288155
S. Krakauer
This paper deals with a p-n junction device which will be called a "Step Recovery Diode" because its conductivity variation during reverse recovery approximates a step function. The transition from reverse storage conduction to cutoff for this diode can occur in about a nanosecond, and it can produce associated discontinuities up to about an ampere and/or a hundred volts. This step recovery action can be conveniently used to generate waveforms which are very rich in high-order harmonics in the gigacycle region. In many cases it offers considerable advantage in circuit simplicity and power-handling capability over alternative diode harmonic generators. This paper is concerned with the factors that go into the appropriate mating of this diode with its circuit, and with evaluation of the performance that can be achieved. As a by-product of this analysis, a generalized evaluation of rectification efficiency is obtained which is useful for many conventional semiconductor diodes in conventional rectifier circuits. This analysis also leads to a convenient method for evaluating the lifetime of semiconductor diodes, which is particularly useful in the fractional nanosecond range because it separates out capacitive effects.
{"title":"Harmonic Generation, Rectification, and Lifetime Evaluation with the Step Recovery Diode","authors":"S. Krakauer","doi":"10.1109/JRPROC.1962.288155","DOIUrl":"https://doi.org/10.1109/JRPROC.1962.288155","url":null,"abstract":"This paper deals with a p-n junction device which will be called a \"Step Recovery Diode\" because its conductivity variation during reverse recovery approximates a step function. The transition from reverse storage conduction to cutoff for this diode can occur in about a nanosecond, and it can produce associated discontinuities up to about an ampere and/or a hundred volts. This step recovery action can be conveniently used to generate waveforms which are very rich in high-order harmonics in the gigacycle region. In many cases it offers considerable advantage in circuit simplicity and power-handling capability over alternative diode harmonic generators. This paper is concerned with the factors that go into the appropriate mating of this diode with its circuit, and with evaluation of the performance that can be achieved. As a by-product of this analysis, a generalized evaluation of rectification efficiency is obtained which is useful for many conventional semiconductor diodes in conventional rectifier circuits. This analysis also leads to a convenient method for evaluating the lifetime of semiconductor diodes, which is particularly useful in the fractional nanosecond range because it separates out capacitive effects.","PeriodicalId":20574,"journal":{"name":"Proceedings of the IRE","volume":"26 1","pages":"1665-1676"},"PeriodicalIF":0.0,"publicationDate":"1962-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85372693","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 : 1962-06-01DOI: 10.1109/JRPROC.1962.288194
W. Highleyman
Many pattern recognition machines may be considered to consist of two principal parts, a receptor and a categorizer. The receptor makes certain measurements on the unknown pattern to be recognized; the categorizer determines from these measurements the particular allowable pattern class to which the unknown pattern belongs. This paper is concerned with the study of a particular class of categorizers, the linear decision function. The optimum linear decision function is the best linear approximation to the optimum decision function in the following sense: 1) "Optimum" is taken to mean minimum loss (which includes minimum error systems). 2) "Linear" is taken to mean that each pair of pattern classes is separated by one and only one hyperplane in the measurement space. This class of categorizers is of practical interest for two reasons: 1) It can be empirically designed without making any assumptions whatsoever about either the distribution of the receptor measurements or the a priori probabilities of occurrence of the pattern classes, providing an appropriate pattern source is available. 2) Its implementation is quite simple and inexpensive. Various properties of linear decision functions are discussed. One such property is that a linear decision function is guaranteed to perform at least as well as a minimum distance categorizer. Procedures are then developed for the estimation (or design) of the optimum linear decision function based upon an appropriate sampling from the pattern classes to be categorized.
{"title":"Linear Decision Functions, with Application to Pattern Recognition","authors":"W. Highleyman","doi":"10.1109/JRPROC.1962.288194","DOIUrl":"https://doi.org/10.1109/JRPROC.1962.288194","url":null,"abstract":"Many pattern recognition machines may be considered to consist of two principal parts, a receptor and a categorizer. The receptor makes certain measurements on the unknown pattern to be recognized; the categorizer determines from these measurements the particular allowable pattern class to which the unknown pattern belongs. This paper is concerned with the study of a particular class of categorizers, the linear decision function. The optimum linear decision function is the best linear approximation to the optimum decision function in the following sense: 1) \"Optimum\" is taken to mean minimum loss (which includes minimum error systems). 2) \"Linear\" is taken to mean that each pair of pattern classes is separated by one and only one hyperplane in the measurement space. This class of categorizers is of practical interest for two reasons: 1) It can be empirically designed without making any assumptions whatsoever about either the distribution of the receptor measurements or the a priori probabilities of occurrence of the pattern classes, providing an appropriate pattern source is available. 2) Its implementation is quite simple and inexpensive. Various properties of linear decision functions are discussed. One such property is that a linear decision function is guaranteed to perform at least as well as a minimum distance categorizer. Procedures are then developed for the estimation (or design) of the optimum linear decision function based upon an appropriate sampling from the pattern classes to be categorized.","PeriodicalId":20574,"journal":{"name":"Proceedings of the IRE","volume":"54 1","pages":"1501-1514"},"PeriodicalIF":0.0,"publicationDate":"1962-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80933306","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 : 1962-06-01DOI: 10.1109/JRPROC.1962.288192
S. Sun
This paper describes the application of the magnetoresistance effect to oscillators using the high mobility semiconducting compound InSb as the active element. The first stable oscillator consisted of an InSb Corbino disk in a ferrite pot core reduced to a temperature of -40°C. The frequency was 210 cps and the open-circuited ac voltage was 540 mv, peak to peak. In order to construct a stable oscillator at room temperature, the shape of the semiconductor specimen was modified to a rectangular form composed of narrow strips of InSb joined together with metallic indium. This specimen has a comparatively higher internal resistance and a more pronounced magnetoresistance effect at low magnetic flux densities. A second oscillator using this specimen as an active element in an E-form ferrite core was tested and found to operate stably at a temperature of 25°C, in a frequency range from a few cps up to 300 cps. The maximum output power available was 2.5 mw, at 70 cps. There is no heating-up time required by the oscillator and the oscillation can start immediately under certain initial conditions. The elimination of the equipment to provide the low temperature, i.e., below 0° C for the oscillator has shown that the magnetoresistance effect can be made good use of in electronic devices without requiring a complicated circuit arrangement.
{"title":"Oscillators by Means of Magnetoresistance Effect","authors":"S. Sun","doi":"10.1109/JRPROC.1962.288192","DOIUrl":"https://doi.org/10.1109/JRPROC.1962.288192","url":null,"abstract":"This paper describes the application of the magnetoresistance effect to oscillators using the high mobility semiconducting compound InSb as the active element. The first stable oscillator consisted of an InSb Corbino disk in a ferrite pot core reduced to a temperature of -40°C. The frequency was 210 cps and the open-circuited ac voltage was 540 mv, peak to peak. In order to construct a stable oscillator at room temperature, the shape of the semiconductor specimen was modified to a rectangular form composed of narrow strips of InSb joined together with metallic indium. This specimen has a comparatively higher internal resistance and a more pronounced magnetoresistance effect at low magnetic flux densities. A second oscillator using this specimen as an active element in an E-form ferrite core was tested and found to operate stably at a temperature of 25°C, in a frequency range from a few cps up to 300 cps. The maximum output power available was 2.5 mw, at 70 cps. There is no heating-up time required by the oscillator and the oscillation can start immediately under certain initial conditions. The elimination of the equipment to provide the low temperature, i.e., below 0° C for the oscillator has shown that the magnetoresistance effect can be made good use of in electronic devices without requiring a complicated circuit arrangement.","PeriodicalId":20574,"journal":{"name":"Proceedings of the IRE","volume":"12 1","pages":"1484-1493"},"PeriodicalIF":0.0,"publicationDate":"1962-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85431929","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 : 1962-06-01DOI: 10.1109/JRPROC.1962.287961
F. X. Bostick, H. Smith
In the magnetotelluric analysis proposed by Cagniard, a resistivity profile of a homogeneous stratified earth model is determined from the ratio of the tangential components of the natural electric and magnetic fields at the surface of the earth. This type of analysis is often confused by the fact that apparent resistivity estimates obtained from data recorded at one site on different occasions may vary considerably. Also the apparent resistivities computed from one component of the E field and its orthogonal H field component may be significantly different from those computed from another pair of orthogonal field components. Cantwell points out that these variations may, at least in part, be due to two-dimensional inhomogeneities and/or anisotropies together with randomly polarized magnetotelluric fields. Accordingly he has suggested testing the wave impedance of the earth as a rank two tensor. This paper describes a measurement and analysis procedure developed using a model based on a two-dimensional wave impedance tensor. It was found that a rotation of the measuring axis to minimize the main diagonal terms in the impedance tensor yields a reasonably consistent estimate of the direction and magnitude of a major inhomogeneity in the apparent resistivity profile.
{"title":"Investigation of Large-Scale Inhomogeneities in the Earth by the Magnetotelluric Method","authors":"F. X. Bostick, H. Smith","doi":"10.1109/JRPROC.1962.287961","DOIUrl":"https://doi.org/10.1109/JRPROC.1962.287961","url":null,"abstract":"In the magnetotelluric analysis proposed by Cagniard, a resistivity profile of a homogeneous stratified earth model is determined from the ratio of the tangential components of the natural electric and magnetic fields at the surface of the earth. This type of analysis is often confused by the fact that apparent resistivity estimates obtained from data recorded at one site on different occasions may vary considerably. Also the apparent resistivities computed from one component of the E field and its orthogonal H field component may be significantly different from those computed from another pair of orthogonal field components. Cantwell points out that these variations may, at least in part, be due to two-dimensional inhomogeneities and/or anisotropies together with randomly polarized magnetotelluric fields. Accordingly he has suggested testing the wave impedance of the earth as a rank two tensor. This paper describes a measurement and analysis procedure developed using a model based on a two-dimensional wave impedance tensor. It was found that a rotation of the measuring axis to minimize the main diagonal terms in the impedance tensor yields a reasonably consistent estimate of the direction and magnitude of a major inhomogeneity in the apparent resistivity profile.","PeriodicalId":20574,"journal":{"name":"Proceedings of the IRE","volume":"2 1","pages":"2339-2346"},"PeriodicalIF":0.0,"publicationDate":"1962-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78377018","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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