Abstract: The study proposes an improved Gabor order tracking technique based on Viterbi algorithm (V_GOT) to cope with close orders and crossing orders that cannot be effectively separated by using the original Gabor order tracking (GOT) scheme. Time-frequency filter technique is replaced by the viterbi algorithm in the process of the V_GOT. In contrast with the original method of GOT, this technique has some advantages, for example, the use of tachometer and other special hardware are avoided in the method so the application of order analysis is simplified. The principles and algorithms and the order tracking process of the method are discussed indetail. The dual function of the Gabor elementary function can effect the precision of tracked orders. In the paper, its influence on the computed Gabor expansion coefficients is investigated. For applying V_GOT in practical work, the separation and extraction of close orders components of vibration signals measured from an aircraft engine test is illustrated. It is suitable for extracting variable amplitude and frequency order in time-frequency domain, and vibration response characters from complex rotating machinery.

Key words: Gabor order tracking, Order analysis, Rotating machinery, Time-frequency analysis, Viterbi algorithm