Filter Considerations - Keithley 2182 User Manual

Filter considerations

The filter configuration for DCV1 is applied separately to each measurement phase (V1t1 and
V1t2) of the Delta process.
NOTE The repeating filter cannot be used for Delta measurements. When Delta is selected,
the Filter will automatically switch to the moving filter if the repeating filter was
enabled.
Moving filter — After filtering yields a reading for V1t1, an output trigger is sent. After
filtering yields a reading for V1t2, another output trigger is sent. The Delta calculation is
performed and the reading is displayed.
For example, assume the filter count for the Moving Filter is 5. Two filter stacks are used: one
for V1t1 readings and one for V1t2 readings. The filter stack for V1t1 readings is filled with five
measurement conversions. The five readings are averaged to yield the V1t1 value and an output
trigger is sent on each V1t1 A/D conversion. The filter stack for V1t2 readings is then filled with
five measurement conversions. The five readings are averaged to yield the V1t2 value and an
output trigger is sent. On each V1t2 A/D conversion, the Delta calculation is performed using
the filtered V1t1 and V1t2 values and the result is displayed on the Model 2182.
For every subsequent Delta measurement, the operation is basically the same except that each
stack only requires one reading to fill it. The oldest reading in each stack is discarded.
NOTE The filter configuration menu cannot be accessed while in Delta. To make filter
configuration changes, you must first disable Delta. This can be done by selecting
Channel 1 (press Delta).
Ratio and Delta 5-15