An apparatus for analyzing the condition of a machine having a rotating part, includes: a first sensor for generating an analogue electric measurement signal; an analogue-to-digital converter for sampling the analogue electric measurement signal at an initial sampling frequency to generate a digital measurement data signal in response to the received analogue electric measurement signal; a device for generating a position signal having a sequence of position signal values for indicating momentary rotational positions of the rotating part; and a speed value generator for recording a time sequence of the position signal values such that there are angular distances and corresponding durations between at least three consecutive position signals, wherein the speed value generator establishes at least two momentary speed values based on the angular distances and corresponding durations, and further momentary speed values for the rotating part are established by interpolation between the two momentary speed values.
