Textbook in PDF format The book is an in-depth guide to efficiently designing optimal-peak-sidelobe polyphase codes. The search for low-sidelobe polyphase codes has challenged researchers since World War II, but the exponential computational complexity of the problem ensures that new insights and algorithms continue to emerge. This resource provides working algorithms and computer code to find ways to build optimal peak sidelobe polyphase codes and code sets. The goal of this book is to narrow the focus to optimal polyphase codes, so as to give a practical limit to the topic, and then to provide readers with the most valuable insights and most efficient algorithms available. Given the demanding timelines of radar and communication system development, this book serves as a practical guide to implementing efficient search methods without starting from scratch. Readers will encounter intriguing connections to Algebraic Group Theory, Combinatorics, and advanced mathematical techniques that drive efficiency in code search and optimization. Whether developing cutting-edge radar waveforms or refining signal processing techniques, this book delivers the tools and knowledge needed to push the boundaries of performance and efficiency. Beyond radar waveform design, the principles explored in this book hold significant relevance for professionals in communications, radio astronomy, and laser optics, where signal integrity and sidelobe suppression are critical. includes combinatorics, quantum sensing, cognitive architectures, and interference mitigation in sensor systems