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Book Review
Sample Rate Conversion in Software Configurable Radios, by Tim Hentschel, Artech House, 2002, ISBN 1-58053-336-1
Reviewed by Vladimir Botchev (vladimir.botchev@analog.com)
The title of this book might at first suggest an overly specialized text. However, even a superficial study reveals that, in fact, what’s taught inside can be used in a much wider context—from digital audio through broadband modems to digital radio. This wider context exists because what’s taught in the book is taught well—both theoretically and from a practical standpoint.
The book’s 288 pages comprise eight chapters and an appendix. Chapter One, the so-called motivational chapter, introduces the topic of sample-rate conversion (SRC) and some of its applications. Chapter Two provides a crash course, very carefully crafted, on sample-rate conversion, conversion side-effects, and multirate systems. The chapter is very informative, and will later prove even more so if the reader has had a previous exposure to multirate signal processing—it will expedite his or her understanding further on.
Chapter Three very briefly details aspects of integer- and-fractional sample-rate conversion concepts in software-radio applications. Chapter four is devoted to integer-factor sample-rate conversion and its effective realization by polyphase filtering. Many practical issues a designer is likely to face are discussed, such as how to organize the polyphase filter computations, how to store coefficients, and quantity of coefficients to store—for example by using an interpolated filter. The chapter also provides a detailed analysis of Farrow-type polynomial filtering, although Farrow filters mostly belong to fractional sample rate conversion and fractional delay.
The next chapter, Chapter Five, presents a highly comprehensive analysis of an important class of digital filters for integer-ratio resampling, the Haugenauer or CIC (cascaded integrator comb) filters. This presentation concludes with a generalization of the concept of the recursive sample-rate converter. Chapter Six introduces fractional-rate conversion, essentially limited to a discussion of integrator dump methods—using CIC filters—and filtering structures using CIC.
Chapter Seven builds on the body of knowledge presented in the previous chapters to discuss optimal strategies for implementing SRC in software radios. The final chapter, very short—just a couple of pages—presents a very useful checklist of “items” that have to be considered or paid attention to when considering the design implementation and integration of a sampling-rate conversion system. The Appendix supplies details of the mathematical analyses for polyphase and CIC filters.
In conclusion, it can be said that this tiny book is extremely useful in a much broader context than its title would indicate.
Reminder:
The 1966 Philbrick Classic:
Applications Manual for Computing Amplifiers for Modeling, Measuring, Manipulating, and Much Else
is now available on the Analog Dialogue web site.
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