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Principles of Operation Teledyne API T801 NDIR CO2 Analyzer Operation Manual
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12.5.7. SOFTWARE OPERATION
The T801 Analyzer is at its heart a high performance, VortexX86-based
microcomputer running Windows CE. Inside Windows CE special software
developed by Teledyne API interprets user commands via the various interfaces,
performs procedures and tasks, stores data in the CPU’s various memory devices
and calculates the concentration of the sample gas.
Windows CE
API FIRMWARE
Analyzer 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
Touch screen
Analog Output Data
RS232 & RS485
External Digital I/O
Measurement
Algorithm
ANALYZER
HARDWARE
PC/104 BUS
PC/104 BUS
Linearization Table
Figure 12-12: Basic Software Operation
12.5.8. ADAPTIVE FILTER
Unlike other analyzers that average the output signal over a fixed time period, the
T801 averages over a set number of samples, where each sample is 1 second.
This technique is known as boxcar averaging. During operation, the software
automatically switches between two different length filters based on the
conditions at hand. 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
amount. Second, the instantaneous concentration must exceed the average in the
long filter by a portion, or percentage, of the average in the long filter.
If necessary, these boxcar lengths as well as the threshold levels can be altered
but with corresponding tradeoffs in rise time and signal-to-noise ratio (contact
Teledyne- API Technical Support for more information).
07274B DCN6418