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Book Reviews Communications equipment and systems lEEConf. Publ. 162 IEE, 1978, 423pp. £18 UK £21.50 overseas As a summary of the current state of the telecommunications art, 'Communications equipment and systems' is a useful publication. The book is the official record of the papers presented at the 'Communications 7 8 ' conference just as they were offered by the authors. The papers are printed in groups under the subjects of the sessions of the conference at which they were presented, so that papers of common interest are adjacent. By its nature the publication cannot provide a gradual introduction to each subject and would be very bewildering to a general reader, although some scene-setting is accomplished by good 'overview' papers. Naturally, also, the quality is variable and some papers are clearly designed to be supplemented by the verbal presentation and visual material. The worst papers are a handful of 'commercial' ones which make little attempt to explain the subject under discussion and seemed designed to impress rather than inform. The best papers are very good, adequately leading into the subject and describing a development of equipment in straightforward English. At £18 (£21.50 overseas) the publication represents good value for qualified workers in the various communication fields anxious to keep up to date in their specialities. D. N. GREGORY
Modern switching theory and digital design S. C. Lee Prentice Hall Internatbnal, 1978, 500pp. £16.75 To most logic designers switching theory conjures up visions of Boolean algebra and a few theoretical design techniques such as the minimisation of logic functions or the use of Karnaugh maps. Also to most logic designers such techniques appear to lack application when it comes to real-life design problems. However, there is more to switching theory than this, and Samuel Lee's text contains those concepts that have occupied theoreticians up to the mid-70s. The term 'modern' refers to topics such as Boolean differential calculus, function classes, multivalued logics, regular expressions and decomposition techniques. In fact, this is an excellent summary of most of the theoretical concepts that have emerged in the field since it was realised that formal analysis could reach beyond simple Boolean algebra representations. Nevertheless, it is a mistake to think that more recent theory is more applicable than its origins. Its value lies not so much in providing techniques that may be used here and there, but in creating as complete a picture as is possible, at present, of the laws that govern digital systems. It is this completeness that makes this an ideal text that is likely to become a standard for those who are interested in theory. This does not mean that the practically minded reader wM be disappointed. The author shows a strong awareness of present-day largescale-integrated technology and has included work on microprocessor-based design and circuits that use read-only memories and prog-
rammed logic arrays as building bricks. Despite what has been said about the lack of applicability, the book contains lucid discussions of topics that have undoubted practical value, such as the theory of fault detection in both combinational and sequential systems. Even the relatively high price is justified by the thoroughness with which the 500pp. have been compiled. I. ALEKSANDER
Digital image processing W. K. Pratt Wiley, 1978, 750pp. £20.80 As evidence of the explosive growth of interest in digital image analysis recently, there have been at least ten books published during the last two years that are totally dedicated to this topic. Of these, this recent addition is by far the most comprehensive in its range of subjects covered. It is also thorough in its treatment and is easy to read, with mathematics being used to support, not replace, narrative. It is possible to read this book with no prior knowledge and become fluent in most of the significant imageprocessing methods to have emerged in recent years. This does not mean that the reader will become an expert image analyst overnight; only experience in designing image analysis systems can achieve that. This book, however, falls short in its coverage of three important topics: namely, hardware, software and the practical skull-duggery that is still an important part of the analyst's art. Nonetheless, in its coverage of algorithms I believe it provides the best value for money. There are numerous topics discussed in this volume, but not by its contemporaries. These include: the psychophysics of vision, photometry and colorimetry, image sampling and coding. It is true that these are covered in more specialised texts than this one, that will find its market among postgraduate students and professional workers in image processing. It would form an excellent course text for a series on the theory of image processing. There are numerous good-quality grey-tone illustrations of the image-analytic algorithms, an important feature in a book on image processing. B. G. BATCHELOR
The 8080A bugbook: microcomputer interfacing and programming P.R. Rony, D.G. Larsen and J.A. Titus Prentice Hall International, 1978, 416pp. £6.95 This is a most peculiar book! The title to start with does nothing to help; it is nothing to do with fault finding. Essentially the book takes a simple single-card type of 8080-based computer and discusses the problem of chip interconnection. The term 'interfacing' is used extensively but largely to mean interconnection of input/output chips with c.p.u. chips, rather than connection of peripheral devices to the computer. The text is extremely repetitive, reproductions of the Intel handbook appearing with monotonous regularity. In fact the body of the
text simply fills out the basic descriptions of the control and status signals associated with the 8080. Descriptions and utilisation details of various support chips are also included, although the age of the text is exposed by the dismissal of the 8228 controller as more expensive than a few other t.t.l. chips. One chapter is laughingly devoted to software, which turns out to be a description of the assembly language mnemonics of the instruction set. Such real world problems as operating systems, compilers or flow charts aFe yet to be discovered! If we wait long enough such devices as debugging aids, simulators and in-chip emulators may yet appear. What this book provides is a guide for people wishing to design detailed logic circuitry for building a simple microcomputer from an 8Q80 microprocessor. There are, however, so many single-card systems already on the market that few newcomers should be involved with this level of circuitry; if anyone has got this degree of freedom at p.c.b. level, then use the 8085 in any case. The fundamental idea of building up the computer is sound from an educational viewpoint, but should only need one-quarter the volume taken. In conclusion, this book played a useful role in the early days of micros, but is now out of date in both concept and content. Engineers must become far more versed in the problems of software engineering and systems design than in putting chips together, a topic adequately covered by the (free) manufacturers' booklets. M. HEALEY
E.L.F. communications antennas M. L. Burrows Peter Peregrinus Ltd., 1978, 245pp. £11.50 Few engineers will be familiar with e.l.f. (extremely low frequency, 30 to 300 Hz) radio communication links. Michael Burrows demonstrates very clearly that e.l.f. is essential if one is to communicate to a station located at depth beneath the ground (e.g.totrapped miners) or beneath the sea. The main theme of the book deals with the problems of establishing a radio link to submerged submarines located anywhere in the earth's oceans. Only e.l.f. offers the possibility of global communication in these circumstances, for only at e.l.f. is the attenuation of the sea water sufficiently small. E.L.F. also offers global propagation within the spherical earth-ionosphere duct with very small path loss and no multipath fading problems. A major portion of the volume (90pp.) deals with the design of the radiating antenna of the US 'Seafarer1 project. It is shown that the optimum practical antenna is a horizontal current sheet realised as a number of buried filamentary currents covering some 10* km* of terrain. The system has the advantage of being 'hard* to nuclear attack. E.L.F. global propagation (68pp.) and receiving antenna design (40pp.) are each discussed very adequately. The work is self contained from the theoretical viewpoint and each chapter concludes with a useful summary. The practicality of 'Seafarer* has been demonstrated. Burrows's book is an excellent account of the technical background to the fascinating project. D. LI. JONES turn to p. 864
