Abstract: In order to process the non-stationary vibration signals such as speed up or speed down signals effectively, a new method combined computed order tracking analysis with empirical mode decomposition technique to analyze the instantaneously signals in the rotate mechanism is explored. Firstly, the vibration signals at start-up in the gearbox are sampled at constant time increments in time-domain and then the data are resampled with software at constant angle increments in an-gle-domain. Therefore, the time domain instantaneously signals is changed into angle domain stationary ones. Then, many IMF components are obtained to decompose the signals in angle domain with empirical mode decomposition (EMD). At last, the high frequency IMF component, which contains the fault in-formation of bearing, is analyzed with order envelope spectrum analysis. The outcome shows it can avoid effectively the “fre-quency smear” phenomenon with order tracking technology, which cannot be solved with the traditional frequency spectrum method and the non-stationary signals are translated into sta-tionary signals. The IMF component, which contains the fault information, can be extracted with EMD. It is trenchancy sup-plement for traditional spectrum analysis combined the order envelope spectrum analysis with EMD, and has more amplitude appliance foreground.

Key words: Empirical mode decomposition, Envelope demodulation, Order tracking, Rolling bearing