Auto Functions - Stanford Research Systems SR810 Manual

Front Panel

Auto Functions

[Auto Reserve]
[Auto Gain]
[Auto Phase]
Pressing an Auto Function key initiates an auto function which may take
some time. The AUTO led in the CH1 display will be on while the
function is in progress. A multi-tone sound will indicate when the auto
function is complete and the AUTO leds will turn off.
Pressing [AUTO RESERVE] will adjust the dynamic reserve to the
minimum reserve required. To do this, the reserve is decreased until the
analog input amplifier is overloaded. The reserve is then increased to
remove the overload.
Auto Reserve will work only if the overloading noise source has a
frequency greater than a few Hz. Lower frequency noise sources may
overload so infrequently that Auto Reserve can not detect it.
[AUTO RESERVE] does not change the notch prefilter settings.
[AUTO GAIN] will adjust the sensitivity so that the detected signal
magnitude is a sizable percentage of full scale. Many time constants are
required to determine whether a particular sensitivity will overload or not.
Auto Gain thus takes a longer time when the time constant is long.
Auto Gain will not run if the time constant is greater than 1 second since
the total time required could be far too long to be useful.
The message 'tc ovEr' will be displayed to indicate that the time constant
is too long for Auto Gain to run.
[AUTO PHASE] adjusts the reference phase shift so that the measured
signal phase is 0°. This is done by subtracting the measured value of q
from the programmed reference phase shift. It will take several time
constants for the outputs to reach their new values during which time q
will move towards 0°. Do not press [AUTO PHASE] again until the
outputs have stabilized. When the measurement is noisy or if the outputs
are changing, Auto Phase may not result in a zero phase.
Auto Phase will not run if the value of q is unstable.
The message 'PhAS bAd' will be displayed to indicate that the phase is
unstable and Auto Phase will not run.
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