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Theory of Operation 
 Model GFC7000TA Carbon Dioxide Analyzer 
 
 
Teledyne Analytical Instruments 
213 
9.5. Software Operation 
The Model GFC 7000TA Gas Filter Correlation Carbon Dioxide Analyzer has a high performance, 
VortexX86-based microcomputer running Windows CE.  Inside Windows CE, special software developed 
by Teledyne Instruments 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
 
Touchscreen/Display 
Analog Output Data 
RS232 & RS485 
External Digital I/O 
 
 
Measurement 
Algorithm 
ANALYZER 
HARDWARE
 
PC/104 BUS
 
PC/104 BUS
 
Linearization Table  
 
Figure 9-18: 
Basic Software Operation 
 
9.5.1. Adaptive Filter 
The GFC 7000TA software processes the CO2 MEAS and CO2 REF signals, after they are digitized by 
the motherboard, through an adaptive filter built into the software.  Unlike other analyzers that average 
the output signal over a fixed time period, the GFC 7000TA averages over a set number of samples, 
where each sample is 0.2 seconds.  This is 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.   
During conditions of constant or nearly constant concentration the software, by default, computes an 
average of the last 750 samples, or approximately 150 seconds.  This provides the calculation portion of 
the software with smooth stable readings.  If a rapid change in concentration is detected the filter