SPM leonova emerald, User Manual

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Shock pulse measurement
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Zoom factor
True zoom is selected to get a high resolution around a
selected ‘centre frequency’. This frequency must be within
the selected frequency range. Thus, to zoom in on 600 Hz,
the minimum range is 0 to 1000 Hz. The range covered by
the zoom is ‘upper frequency range/zoom factor’. Thus,
with a zoom factor of 10, the spectrum will cover the range
550 - 650 Hz.
The highest possible zoom corresponds to a 12800 line
spectrum. For this, combine the lowest number of spectrum
lines, 400, with a zoom factor of 32 (32 x 400 = 12800). With a
centre frequency of 600 Hz, you will get a spectrum over the
range 584.375 to 615.625 Hz, with a resolution of 0.078125 Hz.
Number of spectrum lines
The number of spectrum lines (4) affects the resolution and
the measuring time. Doubling the number of lines also doubles
the measuring time. In cases where different fault symptoms,
such as bearing frequencies and multiples of 1X, are close
together, a high resolution spectrum is preferred.
Saving a full spectrum requires much memory space and
is seldom necessary. Unless the spectrum lines in damage
patterns have fairly high amplitudes, the pattern is not visible.
Thus, saving only peaks (5) will preserve the essential data
while reducing the amount of redundant data. A peak is a
spectrum line that has a line with a lower amplitude on either
side. If you select ‘Save peaks’, Leonova will display the full
spectrum before saving, with peaks as black lines while the
lines to be deleted are grey. The maximum number of peaks
that can be saved is half the number of spectrum lines. The
number of peaks to be saved is input on the number pad.
SPM spectrum type
One unit for amplitude in an SPM Spectrum (6) is SD (Shock
Distribution unit), where each spectrum is scaled so that the
total RMS value of all spectrum lines = 100 SD = the RMS
value of the time record. The alternative unit is SL (Shock Level
unit), the RMS value of the frequency component in decibel.
Average type
To achieve greater accuracy, one can order the average
result from a stated number measurements (average count,
set on the number pad). To get a time synchronous average,
a tachometer must be connected which supplies a trigger
pulse. This starts each measurement with the shaft in the
same position. ‘FFT linear’ (7) gives the mean value of the
measurements, while FFT peak hold gives the maximum value.
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