GPS Made Easy: Using Global Positioning Systems in the Outdoors, 4th Revised Edition by Lawrence Letham

The fourth edition covers improvements in GPS accuracy as a result of WARS (Wide Area Augmentation System). Mary GPS receivers now accept corrective signals from this system of satellites and ground stations. WAAS is referred to in every section of the book describing accuracy. The updated title has new a chapter explaining how to download maps and computer software to a GPS receiver, including examples readers can follow.