Some recent books - IEEE Xplore

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Has the BBC really changed much since those far-off days when, as 2LO, it occupied a goodly slice of the IEE building, sand- wiched between the Savoy Hotel ...
Some recent books Fields and configurations

Radio broadcasting, and now television, has always attracted an unusual concentration of brilliant, yet restless if not actually New York: Holt, Rinehart & Winston, 1965. unstable, collection of administrators, engi635 pp. $14.50 neers and artists. So personality clashes, A field is said 'to exist in a region where resignations and public outcries, examples of certain effects can be observed'. To an which we have seen recently, have always electrical engineer, the term 'field' certainly been part of the BBC scene. Perhaps this calls up the concepts of electric and magnetic could even be the secret of the corporation's fields, possibly also of conduction and thermal undoubted success. fields. But there are several others in physics: 'The golden age' takes us from the formasome obvious, like fluid flow; others more tion of the corporation in 1927 (the first conceptual, like mechanical stress. Between volume covered the BBC's period as a all there are similarities, yet all have unique private company) to the outbreak of war in features. 1939. Prof. Briggs's next instalment will The field is commonly considered as a cover the war years and the last, the period phenomenon in a continuous medium. The up to the passing of the Independent Teleimplication of 'configurations' in the title of vision Act in 1955. Total wordage is expected this book is that nuclear, atomic, molecular to exceed a million. and crystalline media are also considered— This is of course a social history, and those even functional and biological systems. In looking for engineering will not be richly this broad sweep the author, writing from rewarded—although the Baird troubles are Duke University, North Carolina, has pro- covered in some depth. The scholarship and duced a work of admirable scholarship. research that have gone into this work are The treatment is logical. After a descriptive immense, and it makes fascinating reading— introduction, the mathematical tools of field compulsory, one would have thought, for analysis are given in terms of matrixes, anyone in broadcasting. tensors, vectors and methods of solution CALDWELL DAVIDSON (including the well known relaxation and curvisquare methods). The Laplace, Poisson, wave and diffusion equations are discussed. An introduction to the mathematical formulaThereafter the treatment is particularised for tion of self-organizing systems mechanics (particle, multiparticle and wave), J. FORMBY fluid flow, electric and magnetic fields, Spon, 1965. 199 pp. £1 15s. thermal fields, and the electric and magnetic properties of solids. Orthogonal functions, Markov chains, poles The mathematical level is firm but not and zeros, linear dependence, Laplace transesoteric. Altogether the book commands a forms, dynamic programming, phase-plane strong interest in the parallelism, and the trajectories, Lyapunov functions, Hamming several uniquenesses, brought out between distance, superstability, hill-climbing and branches of physics of importance to Wiener filters are some of the stopping points engineers. The material is not new; but the in this masterly guide through the matheco-ordination and presentation are excitingly matical foundations of automatic control. new, and valuable as an attempt to generalise Extracting the concepts with a minimum of and unify the wide spectrum of the field unnecessary detail, the author gives an concept. M. G. SAY account which sparkles with insight. Readers who have already struggled over the difficult terrain will benefit most from this 'aerial view'. The history of broadcasting in the United The book is well written and printed, and Kingdom. Vol. II—The golden age of in most parts the subject-matter flows in a wirelessf continuous manner. Inevitably, a book which covers so large a range leaves a few loose ASA BRIGGS ends. It is to be regretted that only 37 of Oxford University Press, 1965. 688 pp. the 180 pages are given to the main discussion £3 15s. of servomechanisms, self-adapting systems Has the BBC really changed much since and self-optimising systems. The reviewer those far-off days when, as 2LO, it occupied looked in vain for the self-organising systems a goodly slice of the IEE building, sand- promised in the title. J. H. ANDREAE wiched between the Savoy Hotel and Waterloo Bridge? It has, of course, moved with the times—often reluctantly, over- Communication satellites! enthusiastically on occasion—but on reading G. E. MUELLER a n d E. R. SPANGLER the second instalment of Prof. Briggs's Wiley, 1964. 280 pp. £3 15s. magnum opus, it becomes clear that this unique and extraordinary organisation is still In their preface to this survey of the more largely animated by those same ideals of important technical problems involved in public service laid down by Reith more than the design of communication satellites, the 40 years ago. authors state that the information presented JOHN ARTLEY

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derives almost entirely from the work of their colleagues at the Space Technology Laboratories in California. They also point out that no single topic is carried far enough to permit the design of a satellite system, nor has the argument in any case been pushed back to fundamentals. Within these self-imposed limits, a commendably lucid account of this newest of the communication arts is achieved. The topics dealt with include the forecast traffic requirements, the advantages and disadvantages of active as compared with passive satellites, the merits of various orbits, and the characteristics of the space environment and factors influencing the choice of frequency. Other chapters deal with power supplies for use in satellites, methods of satellite attitude and orbit control, the structural design of satellites and temperature-control techniques. The design of the communication system is discussed in terms of modulation methods and Earth-station and satellite-repeater design; the principles of satellite telemetering, tracking and control are outlined. Examples of possible system applications are given, based on the 6, 12 and 24h orbits; the factors influencing reliability and cost are analysed. When describing the technology of satellite design and construction, and when discussing the characteristics of various orbits and the space environment, the authors are evidently on sure ground and their treatment is excellent. It is perhaps less satisfactory as regards the communication-system planning and design, and there are a number of significant omissions from the communication engineer's point of view. For example, the effect of tropospheric attenuation and noise on the choice of frequency is dealt with only cursorily. The conditions of frequency sharing between satellite and terrestrial radio-relay systems, including the power limitations imposed on both systems by the Radio Regulations, and their influence on system design, are not adequately discussed. On p. 164 there is a curious suggestion that, in a frequency-modulation system, one sideband can be eliminated; this is not the case. On p. 172 it is stated that 'the best parabolic antennae have, because of their sidelobes, intrinsic noise temperatures of the order of 50° K, which yield system noise temperatures of 70-100° K\ This is not so, since, with good design, sidelobe and spillover noise from a parabolic reflector can be reduced below 10°K, the overall system noise temperature then ranging from about 45°K to 65°K (zenith to 5° elevation). In spite of the limitations referred to above, the book contains much interesting and useful information, and it will be of considerable value to those concerned with the planning, design and operation of communicationsatellite systems. w. J. BRAY t Copy held in both the lending and reference libraries of the IEE.

Electronics & Power

June 1965