Casella CEL CEL-414 - Manual (Page 16)

3.4Display
Figure 3 shows the display with the vari-
ous parameters that may be indicated as
follows.
Bar Graph & Datum Indicator
This gives an analog indication of the
instantaneous sound pressure level as
soon as the self test sequence has been
completed. It continues to show the
sound level for as long as the instrument
is switched ON and has sufficient battery
power.
The indicated level is consistent with the
settings of the range, frequency weight-
ing, and time weighting switches.
The graph has 26 segments which indi-
cate the level in 1 dB steps above the da-
tum indicated to the left of the bar. When
the level approaches either full scale or
minimum deflection, it is auto-ranged in
20 dB steps, and the new datum dis-
played. This arrangement allows the bar
graph to cover the three full 60 dB dy-
namic ranges of the instrument (CEL-
493/3 has 100 dB dynamic range).
Main Display
This four digit display is the instrument’s
primary indicator. It displays the parame-
ters measured in dB as hundreds, tens,
units, and decimals, and time information
as hours and minutes separated by a co-
lon (:).
When the instrument is first switched on,
the alphanumeric legends “CEL” and
software issue number followed by the
instrument type number and version let-
ter are displayed for approximately 10 s
while the start up sequence is in opera-
tion.
Function Indicators
These are letters that indicate which filter
or weighting network is in use, and a se-
ries of arrows that point towards the leg-
ends on the bezel. The filter and
weighting network indication letters are
as follows.
A A-weighted network,
L Linear response (A, B
& CEL-493/3),
C C-weighted network
(C, D & E versions),
A, F A-weighted network
PLUS internal or
external filter set,
L, F Linear response PLUS
internal or external
filter set.
The arrows indicate which parameter is
being displayed, normally with only one
arrow at a time active as follows.
L eq Equivalent Continuous
Level (not CEL-414/3
and only octave band
L
eq with 328/3C),
SPL Sound Pressure Level,
L max Maximum Level,
DUR Duration over which
measurements taken,
L Tm3 Maximum A-weighted
Average taken over
3 second periods (A, B
& CEL-493/3),
L Tm5 Maximum A-weighted
Average taken over
5 second periods (A, B
& CEL-493/3),
L OSHA Averaged level with a
preset threshold and
q = 5 (C & D versions
but not CEL-414/3),
L DOD Averaged level with a
preset threshold and
Page 12 - General CEL Sound Level Meters Handbook