The Model XDR-928 Expendable Digital Radiosonde represents the state-of-the-art for making precise upper air observations using Global Positioning system (GPS) wind finding technology. It is the first system capable of both radiosonde and dropsonde sounding modes, providing vertical profiles of 3D pressure, temperature, humidity and winds. It can either be released manually or used in the Model ARL-9000 launcher, which includes an integrated METHUB ground station. When supplied with its available 4Hz GPS and IR sea surface temperature sensor options, the XDR can be used with the mobile METHUB for UAV or research aircraft profiling of hurricanes.