A device for decoding magnetic patterns printed on documents comprising a reading head (12) having: a reader (20) arranged to read first magnetic signals belonging to the magnetic patterns and to electromagnetic noise due to sources internal and/or external to the device. The device further comprises: a further reader (40), arranged to read second magnetic signals belonging to the electromagnetic noise, an adder component (25) arranged to algebraically subtract the amplified second magnetic signals from the amplified first magnetic signals, and a converter (16) arranged to convert the resulting signal into a digital signal representing the read magnetic patterns. A method for decoding magnetic patterns is also disclosed.