A method of detecting transients in mechanical systems by matching wavelets
with associated signal is proposed, leading to a development of joint time
-frequency-scale distribution. The three variables, the time, frequency and
scale, have maximised the chance for finding similar signal segments from
a system under inspection. The sensitivity is shown to be very high due to
closer matching and better choice of wavelet shapes, which is essential for
early fault detection and failure prevention. Fundamental types of wavelet
s are introduced based on the shapes of widely encountered system responses
. A method of processing the three-dimensional image is suggested for inter
preting the time-frequency-scale wavelet map, where the properties of the o
bject patterns uncover the features of a signal source, so as to understand
the defect and to indicate the condition of a diagnosed system. The joint
distribution is demonstrated to be useful in detecting transients from diff
erent mechanical systems. Implementation and examples are discussed. (C) 20
01 Academic Press.