Stanford Research Systems SR844, User Manual

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Auto Functions 3-41
SR844 RF Lock-In Amplifier
Auto Functions
Wide
Reserve Shift–
WideResrv
Down
Select the Wideband Dynamic Reserve mode automatically. This function
will execute
once when the keys are pressed. A tone sounds when the
function is complete. The reserve will not continue to change even if the
input signal changes substantially. To adjust for the changed conditions, it
may be necessary to perform the Auto function again, or make manual
changes. The Wide Reserve
AUTO indicator is on while this function
executes.
Close
Reserve Shift–
CloseResrv
Select the Close Dynamic Reserve mode automatically. This function will
execute
once when the keys are pressed. A tone sounds when the function is
complete. The reserve will not continue to change even if the input signal
changes substantially. To adjust for the changed conditions, it may be
necessary to perform the Auto function again, or make manual changes. The
Sensitivity
AUTO
indicator is on while this function executes.
Sensitivity Shift–
SensUp
Automatically adjust the sensitivity based on the detected signal magnitude,
instrument reserve settings and overload conditions. This function executes
once when the keys are pressed. A tone sounds when the function is
complete. The sensitivity will not continue to change even if there is a
substantial change in the input signal. In the case of a substantial signal
change, it may be necessary to perform the Auto Sensitivity function again,
or adjust the sensitivity/reserve manually. Auto Sensitivity takes more time
to complete at larger time constants. The Sensitivity
AUTO indicator is on
while Auto Sensitivity is in progress.
Auto Sensitivity will not execute if the time constant is greater
than 1 s.
Phase Shift–Phase Select the Reference Phase that matches the phase of the input signal. A tone
sounds when the function is complete. This results in a measured phase of
the input signal that is close to zero. If the measured phase of the input
signal is not settled or is noisy at the time
Shift-Phase
is pressed, the
measured phase may not settle to 0
°
.
Auto phase is executed once at the time the keys are pressed. The Reference
Phase will not track changes in the phase of the input signal. However the R
function always provides the magnitude of the input signal, even as the
phase moves, as long as the phase moves slowly compared to the
measurement time constant.
Offset CH1 or CH2
Offset Auto
This key sets the Offset for the displayed quantity equal to the negative of
its current value, so that the display, with offset applied, is equal to zero.
The Offset is turned On if it is not already On. This key has no effect for
quantities that may not be offset.
Important!
If the display is X or Y, Auto Offset is performed on both X and Y and turns
on both X and Y offsets. This is true even if the other display is not
displaying X or Y at the time.