Continuous Wavelet Transform
Figure A8 shows the Continuous Wavelet transform for the 14 chosen records. The time shift in the
CWT varies along the horizontal axis over one rotation of the pinion. The resolution in the time shift
is the same as the resolution in the data, 256 points per rotation. The vertical axis represents each
scale of the wavelet. Low scale and high frequency appear at the top while high scale and low
frequency appear at the bottom of each plot. Scale number 11 maximizes the gear mesh frequency.
The value at each point of the image represents the transformed data at that scale. Notice, for
example, how in record 27 the amplitude oscillates at 19 per rotation in the region around the scale
that maximizes the gear mesh frequency. Also, notice how at the edges of the image the amplitude is
less than it is at the middle of the image. This corresponds to the time data in which the amplitude of
the data also increases in the middle of the rotation.