Casella CEL CEL-414 - Manual (Page 11)

the digital display through the registers.
The following parameters may be se-
lected (and identified) on the digital dis-
play:
SPL Sound Pressure Level,
L eq Equivalent Continuous
Level (not CEL-414/3,
only octave band L
eq
on CEL-328/3E),
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
preset threshold and
q = 5 (C, D versions
but not CEL-414/3),
L DOD Averaged level with
preset threshold and
q = 4 (C, D versions
but not CEL-414/3),
L max Maximum Level ,
DUR Duration over which
measurements taken,
SEL Sound Exposure Level
(not CEL-266/3, CEL-
328/3 or CEL-414/3),
31-16k Octave bands centered
on indicated frequency
(only CEL-266/3 &
CEL-328/3).
Each parameter may be reset inde-
pendently from the other parameters,
while an internal clock with an accuracy
better than five seconds in 24 hours
measures the time elapsed from the start
of the measurement in hours and min-
utes.
The display will give an automatic indica-
tion of the following conditions:
¤ Signal overload,
¤ SEL Event in Progress (CEL-493/3
only),
¤ Use of linear or A-weighted signals
(A & B versions and CEL-493/3),
¤ Use of A- or C-weighted signals
(C & D versions),
¤ Use of an external filter set (not
CEL-266/3 or CEL-328/3),
¤ Use of pause button (not CEL-414/3),
¤ Low battery.
Battery level can also be indicated by us-
ing the “Battery” position on the power
switch.
Both AC and DC analog output signals
proportional to the indicated value are
available from an auxiliary socket in the
base of the instrument. The conditioned
RMS AC output has a full scale deflection
value of 7.75 V, (8.0 V on the CEL-493/3)
while the DC output is a logarithmic sig-
nal nominally 48 mV/dB with a typical
maximum value not exceeding 5 V on all
instruments.
In addition to the analog outputs, the B
and D versions plus the CEL-493/3 are
equipped with a CEL low power digital in-
terface that allows them to feed all digital
data to a CEL-438 Noise Level Analyser,
CEL-338 Graphics Printer and Logger,
and CEL-238A Secondary Processor.
Alternatively, data on the selected pa-
rameter can be fed via a CEL-433 Serial
Interface to a suitably equipped com-
puter. This arrangement is very useful in
data logging applications, as two samples
per second of the SPL display are trans-
mitted in this way.
External control of digital functions is ex-
ercised via the interface, so that parame-
ter selection, and operation of pause and
reset functions can be performed re-
motely, or under program control.
General CEL Sound Level Meters Handbook - Page 7