Abstract: The orbit is expressed as complex process, the theory of complex process high-order cumulant is used in analysis of orbit. The frequency domain characteristic of orbit complex process is discussed combining with shape of orbit. It’s proved that the high-order cumulant of gauss complex noise and noncorrelative noise between Re-part and Im-part is zero, and it is explained that this theory can depress broad noise and narrow band noise. The operating frequency slicing and half operating frequency slicing of bispectrum are defined. The numerical value calculating method of analyzing orbit using bispectrum and slicing of bispectrum is put forward. This method is introduced in the identification of orbit of non-concentric rotor, the analysis result show that this method has two function at the same time, which are orbit purifying and fault signature extracting. The operating slicing of bispectrum is used to analysis the orbit of several faults, the results show that different orbit can be transformed into different value or vectors.

Key words: Complex process, High order cumulant, Orbit, Signature extracting