Casella CEL CEL-393 - Manual (Page 44)

5.2 Frequency Analyser
The filter set comprises charge coupled digitally controlled filters which
may be operated manually or automatically either by the internal micro-
processor or by an associated CEL-160 Graphic Recorder or CEL-238,
-338, -438 Digital Processor/Printers.
Therefore, results are available on the instrument's own display in digital
format, on the interface, or graphically on the recorder. When the filter is
under manual control it may be preset to any band, and then stepped
with +ve or -ve increments.
Microprocessor control provides for four programmed sweeps to be
performed with the results being written to memory. In this case the dwell
time in each band is dynamically controlled to ensure the accuracy of the
result. This enables the filter to be sequentially stepped in the shortest
possible time.
5.2.1 Controls
The filter is selected by means of the Filter switch (Figure 3) and
controlled via control key A (Analyser). The functions of these controls
are as follows:
Wtg - 1:1 - 1:3
In the Off position, the filter circuits are powered down and the signal is
diverted past the filters. In the 1:1 position, the filter is active and the input
signal passed through the filters to produce octave band results. The 1:3
setting is similar, but one third octave bands are produced. When either
of the filter functions are selected, the instrument will always default to
the 1kHz band, and the mnemonic for this band will appear in
po-
sition on the display.
Keypad (Control Key A)
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