Casella CEL CEL-440 - Manual (Page 15)

L AF Sound level, with current weightings (A and F
are shown),
L AFmx Maximum level, with current weightings,
L Aeq Equivalent continuous level, with current
frequency weighting.
All sound level measurement parameters can be set from the keypad
and there are seven overlapping measurement ranges at 10 dB steps
between 10-80 dB and 70-140 dB.
1.7 CEL-480 Sound Level Meter
The CEL-480 is recommended for detailed measurements as, in addition
to the CEL-440 capabilities described above, it features automatic run
timing and scanning facilities controlled by the built-in clock. This allows
it to operate with user preset run durations or start and stop times.
There are time-history recording capabilities that allow up to two
profiles to be saved with each result set in a separate profile store.
Sampling periods can be specified between 1 second and 1 hour, while
profile storage is in excess of 200 000 data points.
1.8 Instrument Power Supplies
All of these instruments are powered by a set of of four standard AA size
batteries located in a compartment in the back of the instrument case,
and it is recommended that alkaline IEC Type LR6 be used.
Rechargeable nickel cadmium batteries may also be employed,
but will give a shorter operating life. Zinc carbon batteries are NOT
recommended. If there is doubt whether the batteries will be able to
power the instrument for the start and stop times set, or when
measurements are needed over long periods, the instrument can be
powered directly from an external 12 V DC supply without the need to
remove the internal batteries.
DAMAGE to the instrument will occur if an
external power supply exceeds 14 V DC. The
nominal external supply is 12 V DC.
Introduction
CEL-440/480 Operators Handbook - Page 15