Casella CEL CEL-296 - Manual (Page 37)

While operating with octave or third octave bandwidths, "All Pass"
may be selected on the BAND switch at any time so that the all pass
level can be inspected on the display. Moving the switch back to its
original "Oct" or "1/3 Oct" setting returns the filter to the frequency
displayed before the interruption without losing its place In the scan
sequence.
Similarly, moving the BAND switch from "1/3 Oct" to "Oct", then back
to "1/3 Oct" again allows the octave band level to be examined
without losing the place in the sequence.
However, if either of the nudge buttons are pressed while "Oct" is
selected, the centre frequency of the OCTAVE band just examined
will now have been chosen when the filter returns to third octave.
When the manual storage of Leq based results Is to be undertaken,
press the "Reset" button on the sound level meter after each value is
stored so that a separate Leq calculation is performed for each
band.
Similarly, if Lmax based data is required, select the appropriate time
weighting (Slow, Fast, Impulse, or Peak) on the sound level meter,
and use the "Reset" button after each filtered level is captured.
A description of how to recall stored results is given in Section 5.1.4.
5.1.3 Operation of Autoscan Storage Facilities
When used connected to CEL sound level meters equipped with the
low power serial interface, the CEL-296/3 Filter Set can perform fully
automatic Leq frequency sweeps and store the calculated results in
digital form. During the analysis, the selected centre frequency is
shown on the right hand side of the display (correctly annotated for
either Hz or kHz). while the left side mimics the display on the meter.
Frequency analysis and data storage in one of five selected
memories can be carried out with both octave and third octave
spectra using the autoscan routine described below.
CEL Instruments Ltd CEL-296/3 Operator Handbook Page 37