US Patent 7613543 Electronic demarcating system

A method and an electronic search system for operating an automatic device, preferably an automatic lawnmower. The system comprises at least one first electrical cable (1,4,5,6) connected to at least one first signal generator (3,7,8) and at least one sensing system arranged on said device. Said sensing system detects at least one magnetic field being transmitted via said cable (1,4,5,6) and propagating through the air, the sensing system transmitting a processed signal to at least one driving element which contributes to the movements of said device in relation to a surface.