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Principles of Operation Teledyne API - T100 UV Fluorescence SO2 Analyzer
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13.7. SOFTWARE OPERATION
The instrument’s core module is a high performance, X86-based microcomputer running
Windows CE. Inside Windows CE, special software developed by Teledyne API
interprets user commands from the various interfaces, performs procedures and tasks,
stores data in the CPU’s various memory devices and calculates the concentration of the
gas being sampled.
Windows CE
API FIRMWARE
Instrument Operations
Calibration Procedures
Configuration Procedures
Autonomic Systems
Diagnostic Routines
Memory Handling
DAS Records
Calibration Data
System Status Data
Interface Handling
Sensor input data
Display Messages
Touchscreen
Analog output data
RS232 & RS485
External Digital I/O
Measurement
Algorithms
INSTRUMENT
HARDWARE
PC/104 BUS
PC/104 BUS
Figure 13-24: Basic Software Operation
13.7.1. ADAPTIVE FILTER
The T100 SO
2
analyzer software processes sample gas measurement and reference data
through an adaptive filter built into the software. Unlike other analyzers that average the
sensor output signal over a fixed time period, the T100 calculates averages over a set
number of samples where each sample is 1 second. During operation, the software
automatically switches between two filters of different lengths based on the conditions at
hand.
During conditions of constant or nearly constant concentration the software computes an
average of the last 240 samples or 240 seconds. This provides the calculation portion of
the software with smooth, stable readings. If a rapid change in concentration is detected,
the adaptive filter switches modes and only averages the last 20 samples or 20 seconds.
This allows the analyzer to respond to the rapidly changing concentration more quickly.
Once triggered, the short filter remains engaged for a fixed time period to prevent
chattering.
Two conditions must be simultaneously met to switch to the short filter. First the
instantaneous concentration must exceed the average in the long filter by a fixed
06807C DCN6650