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6482-901-01 Rev. A / August 2012
Section 4: Range, Digits, Speed, and Filters
Model 6482 Dual-Channel Picoammeter / Voltage Source Reference Manual
Filters
Filtering stabilizes noisy measurements caused by noisy input signals. However, the more filtering
that is used, the slower the measurement process becomes. The Model 6482 uses two stages of
filtering: Average and median. The displayed, stored, or transmitted reading is the result of the
filtering processes.
Filter stages
The Model 6482 uses a two-stage filtering system (see
). The first stage applies the
average filter (moving or repeat) to the measurement conversions. The second stage applies the
median filter to the output of the first stage. When a filter stage is disabled, a reading passes
through it.
Figure 4-2
Two-stage filtering
Each filter stage uses a stack to temporarily store readings to be filtered. The size of a stack, which
is set by the user, determines how many readings will be filtered. A stack size of one (1) disables
that filter.
NOTE
A source level change due to a sweep step resets the filters. That is, readings are flushed
from stack, and the filtering process starts over at the beginning. When not sweeping,
source level changes do not reset the filters.
Any range change will also reset the filters.
Repeat filter
The repeat filter places the specified number of measurement conversions into a stack and
averages them to yield a single repeat filter reading. The stack is then cleared, and the process
starts over. For example, if the repeat count (stack size) is 10, every 10 measurement conversions
will yield a single reading.
illustrates the repeat filter process. The maximum count
(stack size) for the repeat filter is 100. Note that setting the count to one (1) disables the repeat
filter.
Choose the repeat filter for sweeping so that readings for other source levels are not averaged
with the present source level.
Figure 4-3
Repeat filter (count 10)
Analog-to-digital
conversions
Average*
filter
Median
filter
Final
filtered
readings
*Repeat or moving
Conversion #10
#9
#8
#7
#6
#5
#4
#3
#2
Conversion #1
Repeat
reading
#1
•
•
•
Conversion #20
#19
#18
#17
#16
#15
#14
#13
#12
Conversion #11
Repeat
reading
#2
•
•
•
Conversion #30
#29
#28
#27
#26
#25
#24
#23
#22
Conversion #21
Repeat
reading
#3
•
•
•
Содержание 6482
Страница 3: ......
Страница 62: ...Section 4 Range Digits Speed and Filters In this section Topic Page Range and digits 4 2 Speed 4 4 Filters 4 6...
Страница 90: ...Section 7 Sweep Operation In this section Topic Page Sweep types 7 2 Configuring and running a sweep 7 5...
Страница 182: ...Section 14 Common Commands In this section Topic Page Command summary 14 2 Command reference 14 2...