VMI VIBER X5 MKIII, Инструкция по эксплуатации инструмента

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If you collect more averages, you will have fewer random errors. However, collecting
more averages requires more time. If we for example select 8 No of Averages the
instrument will measure 8 different spectra and continuously calculate an average
spectrum. Usually 6 to 8 measurements are enough.
5.1.10. Frequency unit
(Hz or CPM)
With this setting you select which frequency unit to display Hertz (Hz) or Counts per
Minute (CPM).
5.1.11. Overlapping factor
(0, 25, 50 or 75%)
To mitigate the “loss" that can result at the edges of the window (see window
selection),the actual settings may overlap in time. With this factor you can set how much
they overlap.
Most machine vibration signatures are not perfect sinus signals, if a small change occurs in
the signal near the beginning or end of the time record, it will either be analyzed at a
much lower level than its true level or it may be missed altogether (depending on the
characteristics of the windowing function). For this reason, it is a good idea to use overlap
processing.
For 50% overlap, the instrument starts to collect the 2
nd
set of samples when the 1
st
set
has come to half the samples of the time record, 3
rd
set when 2
nd
has come to half
samples of a time record (1
st
set is ended), this process continues until the set number of
averages is collected.
If the overlapping is 75% then the overall time weighting of the data will be flat, and there
is no advantage of using a greater overlap.
Overlapping makes the averaging process faster. The disadvantage is that the greater the
overlap, there are lesser new data, and the influence of random errors will be grater.
5.1.12. Save Waveform with spectra –
If enabled, the analysis file will contain also waveform data.
5.1.13. Speed Measurement –
Measure speed along with the measurement.
5.1.14. Measure BC –
The instrument will measure the Bearing Condition value before measuring spectra (see
the Bearing Condition section under Measurement for further information about this
measurement)