To improve on the existing Android-based datalogger employed by UltraGPR, Groundradar has developed a custom datalogger with a small wrist-mounted display.  The device can accept data from multiple radar receivers at the same time, as well as from two independent GPS receivers.  The primary GPS is a RTK-DGPS capable of positioning accuracy to within +/- 5 cm over base line distances of 10 km.  A secondary GPS provides back-up position and location beneath vegetation to within +/- 3 m.