Casella CEL CEL-296 - Manual (Page 5)

1. INTRODUCTION
The CEL-296/3 Filter Set was designed to meet the requirement for
a portable octave and third octave filter set that allows frequency
analysis to be performed with CEL sound level meters. This
requirement has been realised by utilizing a pair of switched
capacitor filters, one for octaves and one for third octaves, that can
be switched step by step to give the full range of centre frequencies.
The resulting lightweight instrument has 12 octave bands with
centre frequencies from 8 Hz to 16 kHz, and 36 third octave bands
with centre frequencies from 6.3 Hz to 20 kHz. The accuracy of
each individual filter band achieved in this way fulfils the relevant
IEC and ANSI Standard requirements for octave and third octave
filters.
The filter set contains a built in microprocessor plus the CEL low
power serial interface, and in consequence is primarily intended to
operate in conjunction with one of the following sound level
meters.
CEL-493/2N, /3 Precision Integrating Impulse Sound
Level Meter (Type 1I),
CEL-275/28, /2D, /3B, /3D Precision Integrating
Impulse Sound Level Meter (Type 1I),
CEL-363/2B, /2D, /3B, /3D Integrating Impulse Sound
Level Meter (Type 2I).
When fitted to the base of one of these instruments, all of which
contain the interface. a powerful system is formed that can perform
autoscan frequency analysis of noise and vibration under the control
of the microprocessor in the filter set.
Results of the analysis are stored, and this memory is retained even
when the unit is switched off. The memory function enables six
octave and six third octave analyses to be stored, where five of each
CEL Instruments Ltd CEL-296/3 Operator Handbook Page 5