Fluke 8506A Instruction Manual page 47

8506A
2-85,
FILTERING
2-86.
AC
Volts
Functions
2-87.
Two
filter
modes
(off
and on)
are available
when
the
multimeter
is
set
for
ac
volts
measurements (HI
ACCUR,
NORM
AL,
or
ENH'D). The
filter
off
mode
(FG)
is
set
when
changing
into
a
V
AC
function
from
V
DC,
A
DC,
or
OHMS,
Most
V
AC
measurements
use the
filter
off
mode.
The
filter
on
mode
(F)
is
to
be used only
when
the input signal
frequency
is
below 40
Hz.
Degraded
accuracies
result if filter
on
mode
is
used
at
higher
signal
frequencies.
The
filter
mode
can be changed by
toggling
the
FILTER
button
(FILTER
annunciator
is
on
for
filter
on
mode and
off for
filter
off
mode).
When
any
V
AC
function
is
selected while a
V
AC
function
is
already
in
effect,
no
filter
mode
change
is
made.
2-88.
DC
Volts,
Resistance,
DC
Current Functions
2-89.
Five
filter
modes
are
available.
Either of
two
analog
filters
(or
filter
bypass)
may
be
selected.
The
slow
filter
provides
better
normal
mode
rejection.
The
fast
filter
allows for faster
instrument
settling
while
still
providing a degree of noise rejection.
Whenever
a
filter is
used, a
timeout
(for settling delay)
may
also
be
inserted
before each
reading.
No
filtering
is
available for the
external reference inputs.
Table 2-6 defines the
five
filter
modes.
2-90.
Two
methods
of
filter
selection are available in
V
DC,
A
DC,
or
OHMS.
Selection
of
any mode(F,F0,Fl,
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a.
sequence.
The
FILTER
push
button by
itself
toggles
between
modes F
(slow,
no timeout, annunciator on)
and
F0
(fast,
no
timeout,
annunciator
off).
The
multimeter
uses a preset selection
pattern
if
a
mode
other than
F
or
F0
is
already
selected
when
FILTER
is
toggled.
The
slow
filter
(F)
is
always
selected
when
a toggle
is
performed
with a
fast
filter
(F0, FI,
or F3)
in effect.
The
fast filter
(F0)
is
always
selected
when
a
slow
filter
(F or F2)
is
in
effect.
Mode
F0
is
preselected at
power-up
or
reset.
RE1CALL FILTER may
be used at
any time
to verify the
filter
combination
in
use (without
changing
the
filter
mode).
2-91.
AVERAGING
2-92.
The
Averaging
mode
presets the sample
setting to
10 (2
exponent
10
=
1024 samples-per-reading)
and
the
filter
mode
to
F
(slow
filter,
no
time
out).
These
settings
provide
optimum
stability
and
resolution
throughout
the
range of inputs.
Subsequent use of the
SAMPLE
or
FILTER
push button
while
in
Averaging
mode may
jeopardize
this
intended optimization. Therefore,
sample
settings less
than
10
cause the multimeter
to exit
the
Averaging mode. For example,
a
sample
setting of
12,
which
specifies
greater noise rejection
than
the setting of
10, is
accepted and retained for
all
ranges within the
same
function.
Conversely,
a sample
setting
of
7,
offering
less
stability,
is
accepted (but causes the
multimeter
to exit the
Averaging mode).
Table
2-8.
Filter
Modes
(
V
DC,
A
DC,
OHMS)
MODE
NUMBER
FILTER
TIMEOUT
FILTER
LED
(blank)
slow
none
on
o
fast
none
off
1
bypass
none
off
2
slow 550
ms
on
.
3
fast
50
ms
off
(No
Mode Number
is
used
for
slow
filter
without
timeout.
Push
STORE
FILTER.)
2-93. Filter
mode F2
can
also
be
selected in
Averaging
mode.
Any
filter
selected
other
than
F
or
F2
is
accepted by
the
multimeter, but causes deactivation of
Averaging
mode.
2-94.
The
Average
mode
can be used
to
improve
display
stability
(reduce
rattle)
for
measurements
in
V
DC,
OHMS,
or
A
DC.
Averaging
mode
is
not
available in
any
of the ac volts
functions (although the
A VG
pushbutton
can
be used
to
command
extended
resolution
in
V
AC
functions).
In
V
DC,
OHMS,
and
A
DC
functions, the
Average
mode
provides increased display
stability in
all
ranges
and an
increase in
display resolution
in certain
ranges. In
V
DC
(10V range
only), a total
of
7-1
/
2
digits
is
now
available.
Other
V
DC
ranges
still
provide 6-1/2
digits
of
resolution. In
A
DC,
6-1
/
2
digits (instead
of
the
standard
5-1/2) are
now
available in
all
ranges. In
OHMS,
a
total,
of 6-1/2
digits is
available
on
all
ranges.
Preset resolutions
used
for
standard operation
and
for the
Average
mode
are
summarized
in
Table
2-7.
NOTE
When
the
A
verage
mode
is
enabled
in the
10
V
dc range,
the
exponent
field displays the
seventh mantissa
digit
and
does not
indicate
the reading's
exponent.
In this
case the
reading's
decade
multiplier
cannot be
inter-
preted from
the display
if
a
math
function
(such as
offset
or scaling)
is
enabled
.
2-95.
RANGE
2-96.
Ranges
available in
each function are
summarized
in
Table
2-3.
A
power-up
or
reset
condition
sets
the
multimeter
in
the
1000V
range
(V
DC
function),
Autoranging
disabled.
Any
function
selection
enables
Autoranging
(AUTO
annunciator
on).
Autoranging
begins
on
the highest range for each function
(1
000
V
dc,
500V
ac,
100
Megohm,
or
1
A).
In
V
AC
only,
autoranging
begins
at
the previous range
when
selecting
between
V
AC
functions. In
Autoranging, the multimeter
selects
the
range
offering
maximum
resolution for the
measured
value.
The
AUTO
(range)
push button
toggles
Autoranging
mode
on
or
off.
When
toggling
off,
no
range
change
is
effected.
Either of the up/
down
push
buttons
select
manual
ranging
and
step
up/
down
one range
when
initially
used.
Each
subsequent use
steps to the
next
2-25