Keithley 6487, Reference Manual

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4-10 Range, Units, Digits, Rate, and Filters Model 6487 Reference Manual
Digital filter
Digital filter types
An additional filter parameter is type (type is either moving or repeating). Filter types are
compared in
Figure 4-2 .
Moving Filter — Every time a reading conversion occurs, the readings in the stack are
averaged to yield a single filtered reading. The stack type is first-in, first-out. After the
stack fills, the newest reading conversion replaces the oldest. Note that the instrument does
not wait for the stack to fill before releasing readings.
Repeating Filter — Takes a selected number of reading conversions, averages them, and
yields a reading. It then flushes its stack and starts over.
Figure 4-2
Digital filter types; moving and repeating
Conversion #10
#9
#8
#7
#6
#5
#4
#3
#2
#1 Conversion
Reading
#10
Conversion #12
#11
#10
#9
#8
#7
#6
#5
#4
#3 Conversion
Reading
#12
Conversion #11
#10
#9
#8
#7
#6
#5
#4
#3
#2 Conversion
Reading
#11
A. Class - Average, Readings = 10, Type - Moving
Conversion #10
#9
#8
#7
#6
#5
#4
#3
#2
#1 Conversion
Reading
#1
Conversion #20
#19
#18
#17
#16
#15
#14
#13
#12
#11 Conversion
Reading
#2
Conversion #30
#29
#28
#27
#26
#25
#24
#23
#22
#21 Conversion
Reading
#3
B. Class - Average, Readings = 10, Type - Repeating