A robotic lawnmower system, comprising a robotic lawnmower and a charging station, said charging station comprising a signal generator being configured to transmit a boundary signal (A) utilizing CDMA coding having a frame length corresponding to a full frame length through a boundary wire, wherein said signal generator is configured to transmit said boundary signal in subframes, and wherein said robotic lawnmower is configured to receive said boundary signal by detecting magnetic fields generated by the boundary signal, and wherein the robotic lawnmower is configured to determine a set of conditions; and to determine if said set of conditions correspond to a first set of conditions, and if so listen to the subframes, and to determine if said set of conditions correspond to a second set of conditions, and if so listen to the full frames.
