Casella CEL CEL-393 - Manual (Page 43)

factor will have to be used. Due consideration should also be given to
their temperature performance.
There is no known alternative to the CEL-190 microphone fitted to the C
and D version of the instrument.
5 VERSION B - ADDITIONAL FUNCTIONS
5.1 Introduction
This version of the instrument includes a comprehensive frequency
analyser and a computer interface. The presence of these features may
be identified by switching the Off - 1:1 - 1:3 switch from Off to the 1:1
position, which will cause the
mnemonic to appear on the display.
The B version may be specified as original equipment or any A version
of the instrument may be retrofitted following the procedure described in
Section 5.5.
The frequency analyser is a combined full octave and third octave type
that employs digitally controlled charge coupled filter elements. It covers
the range from 6.3Hz to 20kHz, and may be operated either manually or
fully automatically. Automatic control may be exercised by the internal
processor. This produces predetermined sweeps with an optimised time
bandwidth product while retaining the results for each band within the
internal memory. Alternatively, the instrument may be controlled by the
CEL-160 Graphic Level Recorder or the CEL-238, -338, -438 Digital
Processor/Printers, all of which will produce hard copy results.
A modified version of a conventional format is used for the digital
interface in order to conserve internal memory and minimise power
consumption. When connected to a suitable read out system, the inter-
face will download the contents of the internal memory, and then divert
all future answers from the store to the external device.
393 Handbook /39.