A first aspect of the invention relates to an apparatus for mobile application, including a frequency spectrum generator for generating a frequency spectrum of radio waves at a current position of the apparatus and a classifier for classifying the frequency spectrum such that the frequency spectrum is assigned to one of at least two classes. A second aspect of the invention relates to a frequency spectrum generator with a tunable local oscillator, with a downmixer for downmixing a received antenna signal with the local oscillator signal for obtaining a downmixed signal, with a filter for filtering out a mirror-frequency portion in the downmixed signal, with a signal level detector for detecting a signal level of the downmixed signal at an intermediate frequency and with a control for sequentially controlling the local oscillator and the signal level detector to sample a frequency spectrum of the antenna signal.