The present disclosure relates to a self-propelled robotic tool (1) comprising a work implement (3), a driving arrangement (5, 7, 9, 11) for moving the robotic work tool, a control device (13) for controlling the driving arrangement, and an acquisition device (23, 25), configured to record a signal (27； 31) transmitted in bursts by a boundary wire loop (19), wherein the control device is configured to determine whether the robotic work tool is located within an area (17) defined by the boundary wire loop based on the recorded signal. There is provided a digital signal processor (39) which is configured to provide an output corresponding to an average of a plurality of recorded transmitted signal bursts, wherein the control device (13) is configured to determine whether the robotic tool (1) is located within said area (17) at least partly based on said output.
