Casella CEL CEL-278 - Manual (Page 12)

battery voltage falls to an unusable level, and whether an overload condition
is occurring. Figure 3 shows the full annotation provided by the display,
where the indications are as follows.
CENTRE FREQUENCIES
These are the octave band centre frequencies from 16Hz to 16kHz.
If, in the middle of a frequency scan, the WTNG (weighting) switch is used to
select the C-weighted or all pass bands then moved back to the "Oct"
position, the instrument remembers which octave band was selected and
returns to it.
AP
This is an all pass band that can be selected manually by moving the WTNG
switch to "All Pass", by pressing the
and buttons to scan the filter
bands, or by remote switching.
When the Filter Set is switched on, this marker will ALWAYS be the
automatic first selection, irrespective of the WTNG switch position, and gives
an indication that the instrument is operating. The marker will remain selected
when the WTNG switch is moved to "C" or "Oct".
OVERLOAD
This indicates when the Filter Set itself is being overloaded, and remains lit
for the duration of the overloaded condition.
If OVERLOAD is indicated during a measurement, the instrument settings
must be corrected to remove it from the display. Either select a higher range
on the Sound Level Meter, or move the Filter Set range switch from "Lo" to
"Hi".
LOW BAT
This Indicates that the voltage supplied to the CEL-278 is below
approximately 3.2V, and that either the internal batteries must be re-
Page 12 CEL-278/2 Handbook CEL Instruments Ltd