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Principles of Operation
8.8. SOFTWARE OPERATION
Windows CE
API FIRMWARE
Memory Handling
DAS Records
•
Calibration Data
•
System Status Data
•
Measurement
8.8.1. ADAPTIVE FILTER
304
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.
Algorithms
Figure 8-25:
The T200H/M NO
analyzer software processes sample gas concentration data through a
X
built-in adaptive filter. Unlike other analyzers that average the output signal over a fixed
time period, the T200H/M averages over a defined number of samples, with samples
being about 8 seconds apart (reflecting the switching time of 4 seconds each for NO and
NO
). This technique is known as boxcar filtering. During operation, the software may
X
automatically switch between two different filter lengths based on the conditions at hand.
During constant or nearly constant concentrations, the software, by default, computes an
average of the last 42 samples, or approximately 5.6 minutes. This provides smooth and
stable readings and averages out a considerable amount of random noise for an overall
less noisy concentration reading.
If the filter detects rapid changes in concentration, the filter reduces the averaging to
fewer samples or shorter time to allow the analyzer to respond more quickly. Two
conditions must be simultaneously met to switch to the short filter:
instantaneous concentration must differ from the average in the long filter by at least 50
ppb. Second, the instantaneous concentration must differ from the average in the long
filter by at least 10% of the average in the long filter.
Teledyne API - Model T200H/T200M Operation Manual
Instrument Operations
Calibration Procedures
•
Configuration Procedures
•
Autonomic Systems
•
Diagnostic Routines
•
Interface Handling
Sensor input data
•
Display Messages
Touchscreen
•
Analog output data
•
RS232 & RS485
•
External Digital I/O
•
Basic Software Operation
PC/104 BUS
INSTRUMENT
HARDWARE
PC/104 BUS
07270D DCN7141
First, the
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