Book review - IEEE Xplore

sidebands' will be in antiphase with one another and will cancel. The concept of 'phase noise power' is widely used in practice by synthesiser engineers and should be subject to a simple and convenient notation as suggested above. Philosophic objections to a formal notation are, at bottom, due to a residual tendency amongst some engineers and scientists to adopt the philosophic position known as 'logical positivism' or 'verificationalism'. As this philosophy was conclusively refuted by K.R. Popper many years ago (see Reference 3), and as even A.J. Ayer has had to admit that he has never been able to

produce a satisfactory formulation of the 'verification principle', it should hardly be allowed to dictate the form of engineering concepts in the 1980s. 5

References

1 SHOAF, J.H., HALFORD, D., and RISLEY, A.S.: US National Bureau of Standards technical note 632, Jan. 1973 2 LEESON, D.B.: 'A simple model of feedback oscillator noise spectrum', Proc. IEEE 1966,54, pp. 329-330 3 POPPER, K.R.: The logic of scientific discovery' (Hutchinson, 1959)

Book review Introduction to adaptive arrays

R.A. Monzingo and T.W. Miller Wiley, 1980, 543pp., £19.15, ISBN: 0-471-05744-4

Adaptive signal processing (ASP) concerns the automatic detection and estimation of desired signals in the presence of unwanted noise or interference. ASP remained for some years a subject for the pure mathematician but advances in analogue and digital electronic technology are now providing cost-effective implementations in modern radar, sonar and communications systems. Although practical problems associated with the various applications and implementations are different, the basic underlying theory is much the same. The open literature is densely populated with papers on this subject, but a good introductory reference text reviewing the fundamental principles of adaptive arrays has, until now, been sadly lacking. The book is divided into three parts. Part I (Chaps. 1—3) acts as an introduction to the subject. It lists the principal system components and goes on to develop theoretical performance limits and the Wiener solution. Part II (Chaps. 4—10) provides a survey of the popular adaptive algorithms from the method of steepest descent through to the various accellerated gradient, random search, sample matrix inversion and cascade network techniques. Simulation results are included which provide some insight into the

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relative performance of the various algorithms. Part HI (Chaps. 11 and 12) is concerned with practical problems of implementation and future trends. The major portion of this section deals with the problem of interchannel mismatch. Multipath propagation, propagation delay across the array and mismatched electronics will all contribute to mismatch of received signal spectrum characteristics from channel to channel. This mismatch can severely degrade an adaptive array's broadband performance unless some form of compensation is employed. Chap. 11 addresses the topic of tapped delay line processing as a mismatch compensation technique. Chap. 12 reviews current trends in adaptive array research including maximum entropy spectral estimation. This chapter also briefly covers some partial adaptive array techniques. Problems are presented at the end of each chapter to illustrate and extend the material in the text, and references are provided in abundance for those who wish to pursue each topic further. In summary, the book provides a sound theoretical basis to the subject of adaptive arrays suitable as a reference text at graduate level and a recommended professional reference for practicing engineers and scientists. P.J.BALDWIN

IEEPROC, Vol. 128, Pt. F, No. 3, JUNE 1981