The document provides an overview of unmanned aircraft systems (UAS), including their history and evolution from remote piloted vehicles (RPV) to unmanned aerial vehicles (UAV) to today's unmanned aircraft systems (UAS). It describes various UAS including the Raven, Shadow, Predator, and Global Hawk and discusses their missions, features, and technical specifications. It also discusses spectrum needs and challenges for integrating UAS into national airspace, including the need for protected aeronautical frequency allocations to ensure their safe operation.