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OFFSET FUNCTION
25
This
function
can be used
to
add
or subtract
a value
to
the
measured
frequency,
(Ref.
B17).
It is
also
used
to
subtract the displayed frequency
(nulling)
to
view
drift
or
offset.
For
example:
measuring
the
IF
of
a
radio
receiver, after
entering tbe receiver
local oscillator
frequency
as
a
positive
offset,
enables the
true
input frequency
to
be
displayed.
Setting the Offset
26
If
enabled,
the
offset
frequency entered
is
normally
subtracted
from
the
measured
signal
frequency.
(1)
To
store
the
offset
frequency, send the
command
string
(this
example shows
10.5
MHz),
"OFFSET
+/-10.5E6",
(Ref.
B17). This enters the
offset
frequency
into
the
OFFSET
register.
(2)
To
store
the
measured
frequency
as
an
offset,
send
the
command
string
"OFFSET
DISP",
(Ref.
B17).
Enabling
the Offset
27
To
enable
the stored
offset,
send
the
command
string
"OFFSET
ON". The
OFFSET
function
is
disabled
by sending
"OFFSET
OFF",
(Ref.
B17).
Interrogating the Offset
28
If
necessary
the stored
offset
can be
displayed
at
the
controller
by sending
the
command
"OFFSET?",
(Ref.
B24).
SMOOTH
FUNCTION
29
Selecting
SMOOTH
enables
the
instrument
to
take a 'running average*
of
the input
frequency and
display at the controller those
digits
that are
stable.
Place holding
zeros are
inserted in place of
unstable
digits.
30
To
enable
the
SMOOTH
function
send
the
command
"SF
21,
ON". The
function
is
disabled
by sending "SF
20".
CLK10
FREQUENCY STANDARD
.
31
The
CLK10
Frequency Standard can
be
selected in
preference
to
the external standard, or
the
instruments
own
internal
standard (whichever standard
is
in
use
at
the
time).
32
To
select
CLK10
send the
command
"CLK10
ON".
Sending
"CLK10 OFF"
reverts
the
system
to
the original
frequency standard by switching
the
CLK10
standard
off,
(Ref.
BIO).
4-8
2151
OPS
A1571/DA
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