This resource offers professionals, students and recreational users of GPS a clear non-mathematical explanation of how GPS works and its wide range of applications. It addresses all aspects of the GPS, examines the GPS signal structure and covers the key types of measurement being utilized in the field today. Readers get an in-depth discussion on the errors and biases that affect GPS measurements, along with advice on how to overcome them. Moreover, the book shows how the GPS can be used for a number of different accuracy levels. Datums, coordinate systems and map projections are discussed in a simple manner, offering a clear understanding of this widely misunderstood area. This reference also examines the integration of the GPS with ther systems, and looks at future GPS modernization.