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Set
TRACK
(FREQ
C)
13
This
function enables the
instrument
to
measure
swept
frequencies,
(Ref.
B16).
14
To
use
this
function proceed as
follows:
(1)
Proceed
as described in
'FREQUENCY
MEASUREMENT
-
INPUT
C'.
(2)
Send
the
command
''TRACK ON".
(3)
To
exit this
function
send
''TRACK
OFF".
RATIO
MEASUREMENTS
C/B
(2151
ONLY), C/A
(2151
ONLY)
AND
B/A
15
These
three Ratio
Modes
use a
'software' ratio
method, whereby
the
denominator
is
sampled
first,
followed
by
the
numerator.
The
microprocessor
in
the
instrument then computes
the
ratio.
16
For
certain
specific
applications
a
'hardware' version
of
RATIO
B/A
is
available
by
enabling
Special
Function
91.
This allows
'real
time'
ratio
measurements
to
be
made.
(1)
To
select
the relevant
RATIO
function,
send
the
command
"RACB
x"
(Ref.
B7),
"RACA
x"
(Ref.
B6)
or
"RABA
x"
(Ref.
B5).
NOTE:
"x"
is
a
number
entered,
in
the
range
3
to
10,
to
set
the
reading
resolution.
Gate time
is
related
to
the
resolution
selected.
If
omitted
the previously
set
resolution
will
be
used.
(2)
If
INPUT
A
is
being
used:
(a)
For
a frequency
below
50
kHz
in
the presence
of
HF
noise, select
the
Low-Pass
Input
Filter
(''FILTA
ON"),
(Ref.
B9).
(b)
If
required
select
the
Attenuator
("ATTENA
ON"),
(Ref.
B8).
CAUTION: SIGNAL
LEVEL
ENSURE THAT THE
INPUT SIGNAL LEVEL DOES
NOT EXCEED
THE
DAMAGE
LEVELS
SPECIFIED
IN
SECTION
1
OF
THIS
MANUAL.
NOTE:
INPUT B
is
fused,
see
SECTION
1
of
this
manual.
(3)
If
HOLD
mode
operation
is
required,
use the
command
"HOLD
ON",
(Ref.
Bll).
To
take a
measurement,
use the
"MEAS?"
or
"*TRG" command.
(a)
"MEAS?"
(Ref.
B12)
automatically
enters the result in the
instrument's output
queue.
(b)
If
''*TRG"
(Ref.
A14)
is
used,
then send "DISP?"
(Ref.
B13)
to
enter the reading
in
the output
queue
(4)
To
return
to
continuous
measurement mode
send
"HOLD
OFF".
4-6
2151
OPS
A1571/DA
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