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Setup Menu T400 Ozone Analyzer Operator’s Manual
94
5.2. SETUP DAS: INTERNAL DATA ACQUISITION SYSTEM
Use the SETUP>DAS menu to capture and record data. Refer to Section 7 for
configuration and operation details.
5.3. SETUP ACAL: AUTOMATIC CALIBRATION OPTION
The menu button for this option appears only when the instrument has the zero span
and/or IZS options. See Section 9.4 for details.
5.4. SETUP RNGE: ANALOG OUTPUT REPORTING RANGE
CONFIGURATION
Use the SETUP>RNGE menu to configure output reporting ranges, including scaled
reporting ranges to handle data resolution challenges. This section also describes
configuration for Single, Dual, and Auto Range modes.
5.4.1.1. Physical Range versus Analog Output Reporting Ranges
Functionally, the Model T400 photometric analyzer has one hardware “physical range”
that is capable of determining O
3
concentrations between 0 ppb and 10,000 ppb. This
architecture improves reliability and accuracy by avoiding the need for extra, switchable,
gain-amplification circuitry. Once properly calibrated, the analyzer’s front panel will
accurately report concentrations along the entire span of its physical range.
Because, most applications use only a small part of the analyzer’s physical range, the
width of the T400 analyzer’s physical range can create data resolution problems for most
analog recording devices. For example, in an application where the expected
concentration of O
3
is typically less than 500 ppb, the full scale of expected values is
only 5% of the instrument’s 10,000 ppB physical range. Unmodified, the corresponding
output signal would also be recorded across only 5% of the range of the recording
device.
The T400 solves this problem by allowing the user to select a scaled reporting range for
the analog outputs that only includes that portion of the physical range relevant to the
specific application.
Note Only the reporting range of the analog outputs is scaled. Both the DAS
values stored in the CPU’s memory and the concentration values
reported on the front panel are unaffected by the settings chosen for the
reporting range(s) of the instrument.
06870C DCN6332