Textbook in PDF format This book offers a comprehensive exploration of indoor acoustic positioning systems designed for environments where GPS is ineffective. It thoroughly examines the design and implementation of sound-based positioning systems (SPS), focusing on methods such as Time of Arrival (ToA), Angle of Arrival (AoA), and Time Difference of Arrival (TDoA) to achieve accurate 3D localization. The book addresses challenges including Doppler shifts from moving robots, signal reflections (multipath) due to obstacles, and environmental factors like wind and temperature variations that affect acoustic signal propagation. By providing detailed analysis and practical mitigation strategies, it equips readers with solutions to enhance SPS accuracy and reliability. Special features include illustrative diagrams, comprehensive tables, and an appendix containing key function code for building a ToA-based acoustic positioning system—facilitating hands-on learning and implementation. This resource will be invaluable to robotics engineers, indoor navigation system developers, and researchers in autonomous systems who seek to design and deploy reliable indoor positioning solutions in GPS-denied environments