Detecting and Classifying Low Probability of Intercept Radar [Book Review]

The art of designing and constructing radar equipment that is hard to detect by the enemy started during the final years of World War 11. It has recently evolved to an interesting topic inside electronic warfare and was nicknamed “LPI.” Anti-radiation missiles must be one of the key reasons radar manufacturers are keen on finding new solutions to their equipment, hardware, and algorithms. Of course, there is a continuous dogfight ongoing among intercept receiver designers trying to figure means to overcome the challenges posed by new radar constructions and waveforms. The best radar in this context is the one which never transmits, but obviously, will never see very much either. Our classical radar equation could naturally be blamed because it dictates that any reasonable on-board intercept receiver will get much higher input levels than the radar. However, it is pretty hard to change fundamental physics. The very new book Defecting and Clnssifying Low Probability of Intercept Radar, authored by ProfessorPhillip E. Pace, gives new elements to thediscussion. This book is divided into two main parts and twelve chapters. In a clever way, Professor Pace first uses seven chapters to discuss various aspects of LPI radar and then, in the second part, he focuses on intercept receiver design. Chapter 1 is, in a way, an introduction to the LPI world and contains basic concepts and definitions. Several applications are illustrated in Chapter 2. An entire chapter is then devoted to LPI waveform ambiguity analysis. The most common technology, FMCW radar is treated in Chapter 4. Chapters 5 and 6 go through the major topics of phase shift and frequency shift keying methods in radar. Then, in Chapter 7, the reader is guided into a case study tour of missile seeker-head design. Intercept receiver fundamentals are highlighted in Chapter 8. After that, the author presents three methods for LPI radar signal handling in a non-cooperative receiver. Wigner-Ville distribution analysis in Chapter 9, quadrature mirror filtering in Chapter 10, and cyclostationary spectral analysis in Chapter 11. Finally, Chapter 12 gives very brief concluding remarks and a look to the future where automatic and autonomous detection of LPI radars is to spread out. The last part of this book contains 16 appendices that show examples of processing results in Matlab and highlight the mathematics behind Costas frequency hopping sequences. The author, Dr. Phillip E. Pace, is a professor in the Department of Electrical and Computer Engineering at the Naval Postgraduate School. He received his B.S. and M.S. degrees from Ohio University in 1983 and 1986, respectively. Following the good-old US tradition of studying in at least two separate academic institutions, he then went to the University of Cincinnati to defend his Ph.D. thesis in the field of electrical and computer engineering. Before selecting the educational path, Professor Pace worked for five years at Hughes Aircraft Company’s Radar Research Group, and for two years at General Dynamics where his position was in the field of radar systems research. His enthusiastic work in the field of electronic warfare has earned him the Outstanding Research Achievement Award at NPS in 1994, 1995, and 1998. The Association of Old Crows has given him the Academic Training Award in 1995. Professor Pace is the director of the Joint Services Electronic Warfare Center at N P S and the chairman of the Navy’s Threat Simulator Validation Working Group since 1998. He was a member of the Navy’s NULKA Blue Ribbon panel in 1999. Besides the book currently under review, Professor Pace has authored Advanced Techniques for Digital Receivers, published by Artech House in 2000. His professional focus is on receiver design, electronic warfare, and weapon systems. He is a Senior Member of IEEE and a member of AOC. Simple numbers indicate that this book has about 240 equations and 330 illustrations in its 455 pages. However, almost 100 of the illustrations are collected in the appendices (sixteen in total!). The number of tables is just 15 and there are over 200 references, but some overlapping may occur due to the publisher’s requirement of having a list of references after each main chapter. The alphabetical index has roughly 550 items and there are about 50 problems that certainly can be utilized in engineering education. As many signal processing books, also Defecting and CIassifving Low Probabiliry of Intercept Radar tends to be mathematical, but I did not find it too burdensome myself, despite the fact that my success in the