TSI Instruments ALNOR MicroManometer AXD 550, Руководство пользователя

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Appendix B:
Time Constant Averaging Technique
The averaging technique is common to many types
of instrumentation. It also tends to increase the
display rate of the microprocessor on the LCD. In
other words, the lower the time constant value, the
higher the percentage of the new value is
displayed at an increased time rate.
This technique uses a percentage of the newly
acquired value and adds it to a percentage of the
“old” value. The two percentages must add up to
100%. The meter then displays the resultant value.
This displayed value then becomes the “old” value
while a new pressure is being measured. Then the
process starts over. By using less than 100% of the
new value for the displayed reading, a more stable
displayed reading results. The following table
shows the [
] value and the percentages of new
and old values that will be used.
In any circumstance, if the new value is more than
50% different than the old value, 100% of the new
value will be used. This “override” percentage
allows the meter to quickly attain a new value
when the higher [
] settings are used, and
provides the desired damping to typical input
fluctuations. Without this feature, the meter would
take a long time to reach its final value when
exposed to large changes in input value.
Setting New Value % Old Value %
Time to Reach
95% of input is
less than override
%
Time to reach
input if more than
override %
Override %
1 100% 0% 1.5 seconds 1.5 seconds 50%
2 50% 50% 6.0 seconds 1.5 seconds 50%
3 25% 75% 12 seconds 1.5 seconds 50%
4 10% 90% 34 seconds 1.5 seconds 50%
5 5% 95% 68 seconds 1.5 seconds 50%
Note: The time at 1.5 seconds is the time to reach input if more than override % column corresponds to two update intervals.
Depending on when in the update cycle the stop change would occur, this is the maximum time which would be needed to see the
change. It is possible to view the change after one update.