The RABV nuclear reconnaissance system, developed with MoD Institute of Military Technology, mounted on UAV robot plane is intended to serve for determining the radiation level on any ground surface from the air considering flying-altitude, atmospheric and ground conditions. By indicating points with radiations significantly different from background radiation, the system determines the topographical coordinates of single radiation sources. The system is based on a BNS-98L dose-rate data logger. Measuring range of gamma radiation is seven orders from natural background. If the measured value significantly different from background radiation the applied special algorithm changes time constant. The device is developed to operate under extreme meteorological and mechanical conditions. Memory card can be replaced from outside the instrument and can be connected to the evaluating computer by a data reader with USB port.