4.4
Commands
4 – 9
4.4.4
Reference and phase commands
Reference phase
PHAS(?)
{
f
}
Set (query) the reference phase shift
{
to
f
}
, in degrees. Phase must be
in the range 0
≤
f
<
360. The default value is
PHAS
0.00
.
PHAS 30.25
Example:
Phase quadrant
QUAD(?)
{
z
}
Set (query) the phase quadrant
{
to quadrant
z
=
(
I 1
,
II 2
,
III 3
,
IV
4
)
}
. Note that quadrants tokens are Roman numerals.
The quadrants are defined so that
QUAD
I
corresponding to 0
◦
≤
φ <
90
◦
,
QUAD
II
to 90
◦
≤
φ <
180
◦
, and so on.
Commanding a new value of
QUAD
adds or subtracts multiples of 90
◦
to the current
PHAS
setting to bring the phase into the commanded
quadrant.
PHAS 105.25
Example:
QUAD?
2
Reference mode
FMOD(?)
{
z
}
Set (query) the reference mode
{
to
z
=
(
EXT1F 0
,
INTERNAL 1
,
EXT2F
2
,
EXT3F 3
,
RVCO 4
)
}
.
FMOD INTERNAL
Example:
Reference oscillator frequency
FREQ(?)
{
f
}
Set (query) the reference oscillator frequency
{
to
f
}
, in hertz. The
default value is
FREQ
1000.00
.
The set form of the command is only allowed when the oscillator
mode is
FMOD
INTERNAL
. The parameter
f
must be in the range de-
fined by by the
FRNG
command. Queries while in
FMOD
INTERNAL
mode return the commanded oscillator frequency.
Queries in either external or rear-VCO modes return the most re-
cently measured value of the oscillator frequency. Note that the
FREQ?
query itself does not initiate a new measurement of the oscil-
lator frequency. That action is performed with the
AREF
command.
FREQ?
Example:
137.036000000
SR124
Analog Lock-In Amplifier
