A diagnostic device for analyzing a state of a rotating machine that is operated under various rotational speeds, wherein the diagnostic device comprises: - a measurement unit, and - a control unit, wherein the measurement unit is configured to determine a signal having a frequency that changes with respect to the rotational speed of the rotating machine, wherein the control unit is configured to analyze the signal determined by the measurement unit, wherein analyzing the signal comprises: - dividing the signal into a plurality of windows, - extracting a resampling indicator from the signal for each window, wherein the measurement unit is a vibration sensor or a current sensor and wherein, in the case in which the measurement unit is a current sensor, the resampling indicator is a ratio of a maximum frequency value of a predetermined N-th harmonic over all windows, and a frequency value of the predetermined N-th harmonic in the particular window or, in the case in which the measurement unit is a vibration sensor, the resampling indicator is a ratio of a maximum frequency value of a predetermined frequency component over all windows and a frequency value of the predetermined frequency component in a particular window, - resampling the signal for each window by multiplying a number of original data points of each window by the resampling indicator, - generating a resampled overall signal by joining resampled signals of each window. wherein the diagnostic device comprises: - a measurement unit, and - a control unit, - a measurement unit, and - a control unit, wherein the measurement unit is configured to determine a signal having a frequency that changes with respect to the rotational speed of the rotating machine, wherein the control unit is configured to analyze the signal determined by the measurement unit, wherein analyzing the signal comprises: - dividing the signal into a plurality of windows, - extracting a resampling indicator from the signal for each window, wherein the measurement unit is a vibration sensor or a current sensor and wherein, in the case in which the measurement unit is a current sensor, the resampling indicator is a ratio of a maximum frequency value of a predetermined N-th harmonic over all windows, and a frequency value of the predetermined N-th harmonic in the particular window or, in the case in which the measurement unit is a vibration sensor, the resampling indicator is a ratio of a maximum frequency value of a predetermined frequency component over all windows and a frequency value of the predetermined frequency component in a particular window, - resampling the signal for each window by multiplying a number of original data points of each window by the resampling indicator, - generating a resampled overall signal by joining resampled signals of each window. - dividing the signal into a plurality of windows, - extracting a resampling indicator from the signal for each window, wherein the measurement unit is a vibration sensor or a current sensor and wherein, in the case in which the measurement unit is a current sensor, the resampling indicator is a ratio of a maximum frequency value of a predetermined N-th harmonic over all windows, and a frequency value of the predetermined N-th harmonic in the particular window or, in the case in which the measurement unit is a vibration sensor, the resampling indicator is a ratio of a maximum frequency value of a predetermined frequency component over all windows and a frequency value of the predetermined frequency component in a particular window, - resampling the signal for each window by multiplying a number of original data points of each window by the resampling indicator, - generating a resampled overall signal by joining resampled signals of each window.