The present invention relates to 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 means which contributes to the movements of said device in relation to a surface. Said search
system comprises means by which the first
signal generator (3, 7, 8) of the present invention transmits a current through said first cable (3, 7, 8), said current during a part of time being is in a state of rest where it is substantially constant, said state periodically being interrupted by at least one first characteristic
current pulse.