SPM leonova emerald, User Manual

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D
D:34
Shock pulse measurement
An SPM Spectrum is based on the amplitude
modulation of a high frequency signal. It shows
periodic pulses as frequency lines. Thus, if the
signal contains a strong pulse that is repeated at
one second intervals, there will be a high amplitude
line at 1 Hz.
To change any of the spectrum parameters, mark
the line, touch ‘Edit’ and select the value from a list.
Order tracking
‘Order tracking’ is described on page B:36.
Editing spectrum data
Frequency range
The frequency range (1) is always from 0 to ‘upper frequency’. Set ‘Upper
frequency’ to include 3 or 4 multiples of BPFO (ball pass frequency, outer
race). The narrower the range, the better the resolution.
Window
The choice of ‘Window’ (2) somewhat affects the spectrum line amplitudes.
‘Hanning’ (default setting) and Hamming are the window types most
commonly used to calculate spectra. The difference is often marginal
and should not affect pattern recognition.
FFT type
The spectrum type (3) can be ‘linear’ or ‘power’. In a power spectrum,
the line amplitudes are squared. Thus, high amplitude lines become
more prominent while low amplitude lines are suppressed.
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3
1