Casella CEL CEL-368 - Manual (Page 36)

Both clock and RAM are also powered by an additional back-up battery,
so that neither time information nor memory contents are lost when the
main batteries are exhausted and need changing. The back-up battery
has a usable life in excess of five years, after which it must be replaced.
(Please consult CEL Service Department for details.)
The display has a matrix of 64 x 128 pixels which is sufficient for twelve
lines of information, each with nine characters. Detailed descriptions of
the various displays are included with the instructions given for each op-
eration or control option.
The condition of the main batteries is shown by a battery ikon.
indicates full battery.
indicates low battery, and will be shown when the voltage falls be-
low 3.6 V. This ikon can be removed only by switching the instrument
OFF, replacing the batteries, and restarting the measurement sequence.
The overload indication will appear if the pre-weighting overload de-
tector is activated. The presence of an overload will also be stored with
the relevant data. Similarly, the pause indication
will appear if is
pressed to interrupt logging and an indication will also be stored with the
relevant data.
The display is able to give an indication of the following parameters and
conditions ('though not necessarily at the same time):
Memory use,
Time weighting in use,
Frequency weighting in use,
Measurement range in use,
Current Q value,
Current period time,
Current cumulative period identity,
Current time,
Event time activity,
RUN
PAUSE
Preamplifier
RMS & Log
Conversion Overload
Detector
Analog Sect.
Power Sup.
Digital Sect.
Power Sup.
Analog to
Digital Conv.
EPROM RAM
Clock Microprocessor
Battery
Pack
Memory &
Clock
Back-up Bat.
Select
On/Off
Analog
Digital
930002
Connector
18-line
Display
Linear
ON Key
A-weighting
CEL-225/3
CEL-192 CEL-230 Microphone/
Preamplifier Unit Microphone
(CEL-268)
C-weighting
(CEL-368)
Section
Pre-
amplifier
Section
Bat. Voltage
Analog
Output
Log.
Out.
Power Sup.
Control
OFF
200 V
Polariz-
ing
Supply
Amplifier
(+30 dB)
Calibrate
10 - 80 dB
70 - 140 dB
40 - 110 dB
Cal
Keys
Figure 2: Block diagram for both instruments
Page 32 - CEL-268/368 Operator's Handbook