Larson Davis System 824, Reference Manual

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6-22 824 Reference Manual 11/8/00
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Percentile values & levels - The Ln (percentile levels)
level is that level which is exceeded ‘n’ percent of the
measurement time for the frequency band. By modifying
the six settings, you can select any six percentile values
to be displayed. The settings may be changed at any
time; spectral Ln data are only calculated while running.
To view the spectral Lns in graphical form highlight “Spec-
trum 1” and press the check
c
key.
Use the up
u
and down
d
arrow
keys to move from one spectrum Ln
display to another.
There are six displays showing all of the frequencies for
each of the six Ln values.
Below is an example of one of the “Spectrum” displays.
The following is a brief description of each of the compo-
nents of this display:
• Display label - The Display label identifies the display
which is the SSA-Ln 1(f) display showing L 1.67 for all
of the frequencies in graphical form.
• Ln percentage - Shows Ln percentage being displayed.
• Level at selected frequency - This shows the Ln level at
the frequency selected.
Display label
Ln percentage
Selected frequency
Level at selected frequency
Elapsed time
Graph of Ln at each frequency