Casella CEL CEL-393 - Manual (Page 37)

Half second samples are taken of the sound pressure level to calculate
these values. The results are written into a statistical probability distribu-
tion registered having 0.5dB class widths.
From this the cumulative distribution is determined, and the three per-
centile values exceeded are calculated. These are usually:
L 10 Value exceeded for 10% of the measurement
time,
L 50 Value exceeded for 50% of the time,
L 90 Value exceeded for 90% of the time.
Other values are available as an option. The maximum time period that
may be selected for the calculation of L
n values is 8 hours (480m), due
to the capacity limit of the distribution registers etc. When called to the
display in current mode, answers are updated at the normal display
refresh rate of 0.5 sec.
L max
Figure 6 Storage of events in the "Event" mode. Current period display
under 7F in event mode shows most recent SEL. 0F shows highest of
the event maxima in this mode
890018
Event and current maximum
Event maximum
Event maximum
1st event of many, with:
Start time,
Event max,
SEL,
Duration. 3rd event
Etc. 2nd event
Etc.
393 Handbook /33.