The authors design wave digital filters (WDF) in their work. The purpose of this book is to transmit that experience and knowledge. From the beginning, they draw the reader’s attention to the fact that most real-time applications require speeds that cannot be obtained from off-the-shelf chips; they dedicate a considerable portion of the book to the discussion of circuit design and physical implementation. It is in this context that computing is fully employed, both as a means and as an end. A digital filter is a computer especially designed for a given task. To design that special-purpose computer, a general-purpose computer capable of using a high-level language becomes indispensable. WDFs, which are derived from analog network components using scattering wave variables, have low sensitivity to element variation. This allows them to meet specifications with fewer bits (shorter wordlengths) per coefficient than general digital filters.

While preparing the ground to approach the book’s main subject, the authors give the reader a guided tour of digital signal processing. Once the nature of WDFs and their place in the large world of time-invariant, time-varying, analog, and digital filters and its subclasses of recursive and non-recursive digital filters (or infinite impulse response and finite impulse response filters) is established, the discussion of their implementation leads to a wide-ranging review of circuit design and integration.

To describe the methods available for WDF design and construction and to help in the selection of the most appropriate methods, the book contains a succinct but not superficial review of digital filtering followed by a more detailed discussion of the theory, functions, analysis, and simulation of WDFs. This part is completed by chapter 4, on WDF design with finite wordlength, and chapter 5 on WDF hardware implementation. After covering these topics, the book moves on to discuss the structure of the computing machine itself in chapter 6, on VLSI array processors. Chapter 7 looks in detail at the use of bit-level systolic arrays to build WDF adaptors. The book ends with a short chapter on current research work.

The book contains a few examples that show how the formulae lead to the calculation of design parameters. Several examples of code, written in Pascal and FORTRAN 77, are included. At times no code is given but a flowchart is shown and discussed. Although this book contains abundant material about most of the areas it covers, I cannot recommend it as a textbook. The subjects are not introduced in an ordered manner, and some are not introduced at all, as when one reads (p. 24) that a delay operation “can be performed in hardware by a shift register clocked at the sampling frequency, although in practice, it is often implemented by Random-Access Memory (RAM).” No mention of computers occurs before this sentence. The book contains no exercises that could help the readers verify their grasp of its contents. The illustrations, many of them drawn by plotters, are poor. Since the words “coefficient” and “wordlength” refer to fundamental aspects of WDF theory, it is surprising to find that they do not deserve to be entries in their own right in the index, which is far too short. In their preface, the authors declare that the book is suitable for final-year undergraduates and first-year postgraduates. This may be so, but only as a companion to a main textbook or detailed notes provided in class. Non-students who are doing research in digital signal processing may also benefit from this book. In general, a person who already knows electronics and has some knowledge of digital signal processing and digital filtering will find this book useful in learning another approach to those subjects.