A machine has at least two wheels (at least one of them driven) arranged on a base body and connected with a revolving belt. A transmitter and a receiver are arranged on the base body. The transmitter transmits contactless to the belt a transmitted signal having an oscillation frequency, with the receiver from the belt a reflected signal in response to the transmitted signal. An evaluation device connected to the receiver checks if the reflected signal received by the receiver satisfies an acquisition condition indicating that a speed of the belt is in a predetermined speed range. The evaluation device determines, if the acquisition condition is satisfied, a frequency spectrum which is based of the oscillation frequency and the reflected signal in the predetermined speed range and indicative of a mechanical oscillation characteristic of the belt, and generates a control signal based on the evaluated frequency spectrum.