Fecha de publicación: 22/07/2010 Fuente: WIPO "royal booby" The invention relates to a device and a method wherein tunable transmitters and detectors (receivers) are integrated into a non-linear detection system and a narrow-band signal having a variable frequency is used. The scanable frequency range should be between 10-100 MHz. The frequency acceptance range for the second and third harmonic is adjusted according to the transmit frequency.