Keithley 6220 Reference Manual page 191

Model 6220/6221 Reference Manual
Figure 6-1
Digital filter types: moving and repeating
A) Moving filter (count = 10)
B) Repeating filter (count = 10)
Filter window
The averaging filter uses a "noise" window to control filter threshold. As long as
the signal remains within the selected window, A/D conversions continue to be
placed in the stack. If the signal changes to a value outside the window, the filter
resets, and the filtering process starts over.
The noise window, which is expressed as a percentage of measurement range,
allows a faster response time to large signal step changes (e.g., sweep step). A
reading conversion outside the plus or minus noise window fills the filter stack
immediately.
If the noise does not exceed the selected window, the reading is based on the
average of the reading conversions. If the noise does exceed the selected win-
dow, the reading is a single reading conversion, and new averaging starts from
this point.
The window can only be set remotely and can be assigned any value from 0.00%
to 10%. The filter window is expressed as a percent of range. For example, with
the Model 2182/2182A on the 10V range, a 10% window means that the filter win-
dow is ±1V.
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Averaging Filter, Math, and Buffer
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6-5