Keithley 2651A

Section 7: Command reference Model 2651A High Power System SourceMeter® Instrument Reference Manual
7-198 2651A-901-01 Rev. A / March 2011
smuX.measure.filter.type
This attribute sets the type of filter used for measurements when smuX.measure.filter.enable is enabled.
Type TSP-Link accessible Affected by Where saved Default value
Attribute (RW) Yes Instrument reset
SMU reset
Recall
Saved setups smuX.FILTER_REPEAT_AVG
Usage
filterType = smuX.measure.filter.type
smuX.measure.filter.type = filterType
filterType
The filter type to use when filtering is enabled. Set to one of the following values:
0 or smuX.FILTER_MOVING_AVG: Selects the moving average filter
1 or smuX.FILTER_REPEAT_AVG: Selects the repeat filter
2 or smuX.FILTER_MEDIAN: Selects the median filter
X
SMU channel (for example, smua.measure.filter.type applies to SMU
Channel A).
Details
There are two averaging filter types and one median filter type available. Both repeating and moving types of
averaging filters are available.
For the repeating filter (which is the power-on default), the stack (filter count) is filled, and the conversions are
averaged to yield a reading. The stack is then cleared, and the process starts over.
The moving average filter uses a first-in, first-out stack. When the stack (filter count) becomes full, the
measurement conversions are averaged, yielding a reading. For each subsequent conversion placed into the
stack, the oldest conversion is discarded. The stack is re-averaged, yielding a new reading.
The median filter uses a first-in, first-out stack. When the stack (filter count) becomes full, the “middle-most”
reading is returned. For each subsequent conversion placed into the stack, the oldest reading is discarded. The
stack is then re-sorted, yielding a new reading. If the filter count is an even number, the reading returned is the
average of the two middle readings.
Example
smua.measure.filter.type = 2
Selects the median filter for SMU Channel A. Alternatively,
the value 2 may be replaced with smua.FILTER_MEDIAN.
Also see
reset() (on page 7-151)
setup.recall()
(on page 7-170)
smuX.measure.filter.count
(on page 7-196)
smuX.measure.filter.enable
(on page 7-197)
smuX.reset()
(on page 7-209)
Filters
(on page 3-3)