A method of determining stationary signals for the diagnostics of an electromechanical system comprising the steps of: • measuring an analog waveform signal of the electromechanical system, • converting measured waveform signal to discrete processed signal ( S DP) including vector of time instants and corresponding vector of amplitudes, • splitting the discrete processed signal ( S DP) into subdivided single periods ( S DP1, S DP2,..., S DPn) where each of the subdivided single periods includes different or the same number of samples as other subdivided single periods, • modifying number of samples for each subdivided single periods ( S DP1, S DP2,..., S DPn) by resampling procedure getting subdivided single periods after resampling ( S DR1, S DR2,..., S DRn), where all said subdivided single periods after resampling include the same number of samples, • replacing the vector of time instants on a vector of consecutive integer numbers for each single period after resampling ( S DR1, S DR2,..., S DRn), obtaining subdivided nondimensional single periods ( S DN1, S DN2,..., S' DNn), • concatenating all subdivided nondimensional single periods ( S DN1, S DN2,..., S DNn) into one nondimensional discrete signal ( S N) by forming a sequence of consecutive samples setting up one after another taken from consecutive subdivided nondimensional single periods, • replacing the vector of consecutive integer numbers on a vector of ascending time instants in the nondimensional discrete signal (S N), obtaining a dimensionalized stationary signal ( S Nt), • transforming the dimensionalized stationary signal (S Nt) from time domain to frequency domain, getting a frequencies spectrum, from which a vector of interest frequencies and corresponding vector of amplitudes are extracted to diagnose the electromechanical system and displayed on the visualization device. • measuring an analog waveform signal of the electromechanical system, • converting measured waveform signal to discrete processed signal ( S DP) including vector of time instants and corresponding vector of amplitudes, • splitting the discrete processed signal ( S DP) into subdivided single periods ( S DP1, S DP2,..., S DPn) where each of the subdivided single periods includes different or the same number of samples as other subdivided single periods, • modifying number of samples for each subdivided single periods ( S DP1, S DP2,..., S DPn) by resampling procedure getting subdivided single periods after resampling ( S DR1, S DR2,..., S DRn), where all said subdivided single periods after resampling include the same number of samples, • replacing the vector of time instants on a vector of consecutive integer numbers for each single period after resampling ( S DR1, S DR2,..., S DRn), obtaining subdivided nondimensional single periods ( S DN1, S DN2,..., S' DNn), • concatenating all subdivided nondimensional single periods ( S DN1, S DN2,..., S DNn) into one nondimensional discrete signal ( S N) by forming a sequence of consecutive samples setting up one after another taken from consecutive subdivided nondimensional single periods, • replacing the vector of consecutive integer numbers on a vector of ascending time instants in the nondimensional discrete signal (S N), obtaining a dimensionalized stationary signal ( S Nt), • transforming the dimensionalized stationary signal (S Nt) from time domain to frequency domain, getting a frequencies spectrum, from which a vector of interest frequencies and corresponding vector of amplitudes are extracted to diagnose the electromechanical system and displayed on the visualization device.