A device for decoding magnetic patterns printed on documents, comprising: - a reading head movable along the documents in order to read the magnetic patterns printed on said documents and having a first magnetic reader (20, 112) comprising a first magnetic core and a first coil having a first inductance value and a first resistance value, wherein the first magnetic reader (20, 112) is arranged to read first magnetic signals, said first magnetic signals being related to the magnetic patterns and to electromagnetic noise due to sources internal and/or external to the device; - a second magnetic reader (40, 140) comprising a second magnetic core and a second coil having a second inductance value and a second resistance value, wherein the second magnetic reader (40, 140) is arranged to read only second magnetic signals belonging to the electromagnetic noise; - an adder component (25, 125) arranged to algebraically subtract said second magnetic signals from said first magnetic signals; and - a converter arranged to convert the resulting signal into a digital signal representing the read magnetic patterns, characterized in that the second magnetic reader (40,140) is mounted on said movable reading head at a distance of 1-3 mm from the first magnetic reader, so as to be magnetically decoupled from first magnetic reader, and from the magnetic patterns, in that the first coil and the second coil have the same time constant τ = inductance resistance, in that the second inductance and the second resistance are lower than the first inductance and the first resistance, respectively, and in that the second coil is arranged substantially perpendicularly to the first coil. - a reading head movable along the documents in order to read the magnetic patterns printed on said documents and having a first magnetic reader (20, 112) comprising a first magnetic core and a first coil having a first inductance value and a first resistance value, wherein the first magnetic reader (20, 112) is arranged to read first magnetic signals, said first magnetic signals being related to the magnetic patterns and to electromagnetic noise due to sources internal and/or external to the device; - a second magnetic reader (40, 140) comprising a second magnetic core and a second coil having a second inductance value and a second resistance value, wherein the second magnetic reader (40, 140) is arranged to read only second magnetic signals belonging to the electromagnetic noise; - an adder component (25, 125) arranged to algebraically subtract said second magnetic signals from said first magnetic signals; and - a converter arranged to convert the resulting signal into a digital signal representing the read magnetic patterns, characterized in that the second magnetic reader (40,140) is mounted on said movable reading head at a distance of 1-3 mm from the first magnetic reader, so as to be magnetically decoupled from first magnetic reader, and from the magnetic patterns, in that the first coil and the second coil have the same time constant τ = inductance resistance, in that the second inductance and the second resistance are lower than the first inductance and the first resistance, respectively, and in that the second coil is arranged substantially perpendicularly to the first coil.