Application of orthogonal wavelets to early gear damage detection

Use of the orthogonal wavelet transform to detect abnormal transients generated by early gear damage from the gearbox casing vibration signal is discussed. Orthogonal wavelets, such as Daubechies 4 and harmonic wavelets, are used to transform the time domain synchronous vibration signal into the time-scale domain. The orthogonal wavelet transform uses fast algorithms and decomposes the signal onto the minimum number of wavelet series. However comparison with the non-orthogonal wavelet transform for the same length of discrete data shows that the description of the signal in the 3-dimensional map of the wavelet transform is not sufficiently comprehensive due to limited scales.