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Aerospace telemetry
Book Reviews QUANTV~ ELECTRONICS, by Amnon Yariv. 478 pages, diagrams, illustr, 6 X 9 in. New York, John Wiley & Sons, 1967. Price, $14.95.
AEROSPACE TELEMETRY, Vol. II, edited by Harry L. Stilts. 259 pages, diagrams, ilhistr. 6 X 9 in. Englewood Cliffs, N.J., Prentice-Itall, 1966. Price, $10.95.
Quanlum Eledronics is written for first and second year graduate students in physics and electrical engineering. I t forms the basis of a two-semester course taught for three years by the author at the California Institute of Technology. The book is an excellent theoretlcal introdue~on to the most in~portsnt aspects of quantum electronics. Since it presents a unified treatment of the material it will also appeal to active research workers. A background in quantum mechanics and electromagnetic theo~T at tim senior or first year graduate level is assumed. The first six chapters serve as a review of this material necessary for the understanding of the remainder of the book. The author discusses the low frequency and microwave properties of magnetic ions in solids, and inedudes an analysis of the microwave maser. The last half of tbe book deals with the interaction of optical frequency radiation with matter. The theory of optical resonators and several kinds of lasers are discussed, along with selected topics of nonlinear optics which received its impetus with the development of the laser. Particular emphasis is given to parametric interactions. Because of the large number of topics covered, the treatment is in some cases, of necessity, brief. However, fuildamental principles are stressed, and many references, through 1966, direct the reader to further study. Each chapter closes with a number of problems. There are four appendices inchiding a list of the frequency shifts observed in the stimulated Haman effect of 117 materials. Author and subject indices are included. Those seeking a thorough introduction, eitber as a course text or for self study, will find tbis book of coIlsiderable value. Although it is a rapidly moving fiehl, the stress on fundamentals will make it useful for ~ number of years. JA~N"P. VAN I)ER ZII~L
The present second volume presents gen.erally clear discussions of a number of telemetry topics which have been developing rapidly during the past several years. The editor is to be commended for his avoidance of already widely published material. The first contribution is a discussion of satellite and space probe telemetry by Robert W. Rochelle who pioneered in the development of low power, light weight, spacecraft telemetsy systems (particularly PFM). The greatest criticism of this paper is its attempt to encompass too much material. As a result, many of the subjects are covered in a cursory fashion. For example, tlle seetlo11 oil data storage systems briefly mentions only the on-board magnetic tape recorders and magnetic core devices which have been used on a few of the smaller spacecraft, and the discussions of PCIV[ telemetry systems are brief. By far the greatest value of this chapter is in its discussions of P F M telemetry, where the author's wealth of practical experience is reflected in bls descriptions of the Explorer 12, 14, 15 and Interplanetary Monitoring Platform (IMP's A through E) systems. This concentration on P F M is appropriate, since comparatively little has been publisbed about these systems which have made a very valuable contribution to the space sciences during the past detente. Altbough much has been written about F M data systems, the discussion b y J. g . Crow is a valuable addition to the literature. The matel~ial is well organized, moving from a short history, through an eight-page treat. ment of the theory, to a 33-page section on system analysis. This last section concentrates on system accuracy, starting with a general discussion of the problems of defining and combining e~rors. Five systems of increasing complexity are used for illustration and the peak error is calculated for each of 27 error sources encountered in those systems. Walter O. Frost's contribution is on Single Sideband/FM telemetry. Although the basic
Bell Telephone LaSorato~ies Murray Hill, New Jersey
399
Bo~ R~i~s technique has been applied to telephone and ground-based voice communications for many years, its use for P~. F. telemetry is relatively new. I t is especially applicable to the telemetry of many channels of wide-bandwidth data such as vibration and acoustic data h'om large launch vehicles. The spectra of the individual signal sources are translated into different frequency bands. These are then linearly combined to form a composite signal which frequency modulates a transmitter. The chapter is complete, well organized, and well written by a primary contributer to the development of this technique. The chapter on Adaptive Telemetry--Data Compression, by Daniel Hochnlan mid Donald R. Weber of the Lockheed Missiles and Space Company, contains material on Zero and Firs~ Order Polynomial Predictors and Zero and First Order Polynomial Interpolaters (two and four degrees of freedom). It continues with discussions of data reconstruction and presentation, system organizatien, and design of sample systems. There are several minor criticisms of this chapter; for example, the author implies that demands on ground computers will decrease as a result of on-board compression, whereas they will almost certainly increase due to the need for expansion to meet most data user's needs. Perhaps the greatest weakness is his failure to discuss the expected compression factor for a wider range of data classes. The discussion appeaI~ to be centered around relatively well-behaved data such as spacecr~ft engineering data. It is expected that data froln many types of space sciences experiments (for example, those in which the numbers from the individuM events follow pseudo-random distributions) might require a different treamlent. In spite of this, the chapter contains a number of interesting ideas. The discussions of the adaptive possibilities on p. 195 are especially interesting. Unfortunately, the final chapter of the book on PACM Pulse Amplitude-Code Modulation by Warren F. Link suffers seriously from poor organization and a tendency to ramble. Further, the mQor portion of the text describes a specific implementation of a system, whereas a broader discussion would have been of more value. However, it is still of considerable interest to those telemetry engineers who need a combination of the
400
advantages of P A M ~nd P C M on a single channel. The general evaluation of this book is strongly positive. Nearly evelT designer of space telemetry systems will find it to his advantage to be familiar with its content, (~.EOI~GE~{, LUDWIG
NASA, GoddardSpace Fli~h~ Center Greenbelt, Md. IIOMOLOGY AND ]~EYNMAN INTEGRALS~ by R. C. Hwa and V. L. Teplitz. 331 pages, diagrams, 6 X 9 in. New York, W. A. Benjamin, 1966. Price, $12.50. Field theorists for the past ten years have spent a great deal of effort on the problem of determining the analytic structure of the function of several complex variables defined by Feynman diagrams. The aim of these investigations has been to obtain an insight into the analytic structure to be expected of S-matrlx elements in a field theory or to be postulated in S-matrix theory. Although Feynman diagrams and the associated functions are essentially perturbation theoretic in nature, it has been shown that the Landau equations which determine the location of the singularities admit a natural interpretation as the equations determining the threshold of multiparticle scattering processes if the singularities occur in tile physical region. Similarly, a heuristic proof has been given that the whole set of Landau singularities in the complex region must be present and located as indicated by perturbation theory if the S-matrix is to be analytic, crossingsynunetrie and have pole singularities corresponding to stMfle and unstable particles. These demonstrations give supporb to the notion that the properties of Feynman amplitudes which depend only on the locations of singularities and on the coi/sequenees of unitarity are general properties of S-matrix element~. Fotiadi, Froissart, Lascoux and Pham in 1964 introduced a new method based on homology theory for the study of the ~na~ lytis structure of Feynman functions. Their approach gives a rigorous basis to the method of analytic continuation of a function de-
Journal of '/.'he Fr~nkiia Institute
AEROSPACE TELEMETRY, Vol. II, edited by Harry L. Stilts. 259 pages, diagrams, ilhistr. 6 X 9 in. Englewood Cliffs, N.J., Prentice-Itall, 1966. Price, $10.95.
Quanlum Eledronics is written for first and second year graduate students in physics and electrical engineering. I t forms the basis of a two-semester course taught for three years by the author at the California Institute of Technology. The book is an excellent theoretlcal introdue~on to the most in~portsnt aspects of quantum electronics. Since it presents a unified treatment of the material it will also appeal to active research workers. A background in quantum mechanics and electromagnetic theo~T at tim senior or first year graduate level is assumed. The first six chapters serve as a review of this material necessary for the understanding of the remainder of the book. The author discusses the low frequency and microwave properties of magnetic ions in solids, and inedudes an analysis of the microwave maser. The last half of tbe book deals with the interaction of optical frequency radiation with matter. The theory of optical resonators and several kinds of lasers are discussed, along with selected topics of nonlinear optics which received its impetus with the development of the laser. Particular emphasis is given to parametric interactions. Because of the large number of topics covered, the treatment is in some cases, of necessity, brief. However, fuildamental principles are stressed, and many references, through 1966, direct the reader to further study. Each chapter closes with a number of problems. There are four appendices inchiding a list of the frequency shifts observed in the stimulated Haman effect of 117 materials. Author and subject indices are included. Those seeking a thorough introduction, eitber as a course text or for self study, will find tbis book of coIlsiderable value. Although it is a rapidly moving fiehl, the stress on fundamentals will make it useful for ~ number of years. JA~N"P. VAN I)ER ZII~L
The present second volume presents gen.erally clear discussions of a number of telemetry topics which have been developing rapidly during the past several years. The editor is to be commended for his avoidance of already widely published material. The first contribution is a discussion of satellite and space probe telemetry by Robert W. Rochelle who pioneered in the development of low power, light weight, spacecraft telemetsy systems (particularly PFM). The greatest criticism of this paper is its attempt to encompass too much material. As a result, many of the subjects are covered in a cursory fashion. For example, tlle seetlo11 oil data storage systems briefly mentions only the on-board magnetic tape recorders and magnetic core devices which have been used on a few of the smaller spacecraft, and the discussions of PCIV[ telemetry systems are brief. By far the greatest value of this chapter is in its discussions of P F M telemetry, where the author's wealth of practical experience is reflected in bls descriptions of the Explorer 12, 14, 15 and Interplanetary Monitoring Platform (IMP's A through E) systems. This concentration on P F M is appropriate, since comparatively little has been publisbed about these systems which have made a very valuable contribution to the space sciences during the past detente. Altbough much has been written about F M data systems, the discussion b y J. g . Crow is a valuable addition to the literature. The matel~ial is well organized, moving from a short history, through an eight-page treat. ment of the theory, to a 33-page section on system analysis. This last section concentrates on system accuracy, starting with a general discussion of the problems of defining and combining e~rors. Five systems of increasing complexity are used for illustration and the peak error is calculated for each of 27 error sources encountered in those systems. Walter O. Frost's contribution is on Single Sideband/FM telemetry. Although the basic
Bell Telephone LaSorato~ies Murray Hill, New Jersey
399
Bo~ R~i~s technique has been applied to telephone and ground-based voice communications for many years, its use for P~. F. telemetry is relatively new. I t is especially applicable to the telemetry of many channels of wide-bandwidth data such as vibration and acoustic data h'om large launch vehicles. The spectra of the individual signal sources are translated into different frequency bands. These are then linearly combined to form a composite signal which frequency modulates a transmitter. The chapter is complete, well organized, and well written by a primary contributer to the development of this technique. The chapter on Adaptive Telemetry--Data Compression, by Daniel Hochnlan mid Donald R. Weber of the Lockheed Missiles and Space Company, contains material on Zero and Firs~ Order Polynomial Predictors and Zero and First Order Polynomial Interpolaters (two and four degrees of freedom). It continues with discussions of data reconstruction and presentation, system organizatien, and design of sample systems. There are several minor criticisms of this chapter; for example, the author implies that demands on ground computers will decrease as a result of on-board compression, whereas they will almost certainly increase due to the need for expansion to meet most data user's needs. Perhaps the greatest weakness is his failure to discuss the expected compression factor for a wider range of data classes. The discussion appeaI~ to be centered around relatively well-behaved data such as spacecr~ft engineering data. It is expected that data froln many types of space sciences experiments (for example, those in which the numbers from the individuM events follow pseudo-random distributions) might require a different treamlent. In spite of this, the chapter contains a number of interesting ideas. The discussions of the adaptive possibilities on p. 195 are especially interesting. Unfortunately, the final chapter of the book on PACM Pulse Amplitude-Code Modulation by Warren F. Link suffers seriously from poor organization and a tendency to ramble. Further, the mQor portion of the text describes a specific implementation of a system, whereas a broader discussion would have been of more value. However, it is still of considerable interest to those telemetry engineers who need a combination of the
400
advantages of P A M ~nd P C M on a single channel. The general evaluation of this book is strongly positive. Nearly evelT designer of space telemetry systems will find it to his advantage to be familiar with its content, (~.EOI~GE~{, LUDWIG
NASA, GoddardSpace Fli~h~ Center Greenbelt, Md. IIOMOLOGY AND ]~EYNMAN INTEGRALS~ by R. C. Hwa and V. L. Teplitz. 331 pages, diagrams, 6 X 9 in. New York, W. A. Benjamin, 1966. Price, $12.50. Field theorists for the past ten years have spent a great deal of effort on the problem of determining the analytic structure of the function of several complex variables defined by Feynman diagrams. The aim of these investigations has been to obtain an insight into the analytic structure to be expected of S-matrlx elements in a field theory or to be postulated in S-matrix theory. Although Feynman diagrams and the associated functions are essentially perturbation theoretic in nature, it has been shown that the Landau equations which determine the location of the singularities admit a natural interpretation as the equations determining the threshold of multiparticle scattering processes if the singularities occur in tile physical region. Similarly, a heuristic proof has been given that the whole set of Landau singularities in the complex region must be present and located as indicated by perturbation theory if the S-matrix is to be analytic, crossingsynunetrie and have pole singularities corresponding to stMfle and unstable particles. These demonstrations give supporb to the notion that the properties of Feynman amplitudes which depend only on the locations of singularities and on the coi/sequenees of unitarity are general properties of S-matrix element~. Fotiadi, Froissart, Lascoux and Pham in 1964 introduced a new method based on homology theory for the study of the ~na~ lytis structure of Feynman functions. Their approach gives a rigorous basis to the method of analytic continuation of a function de-
Journal of '/.'he Fr~nkiia Institute