Stanford Research Systems SR780, Operating Manual And Programming Reference

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4-76 Analog Input Menu
SR780 Network Signal Analyzer
Ch1 AutoRange
Select the AutoRange Mode for the Ch1 input [Normal, Tracking]. This mode only
applies when Ch1 Auto Range is On.
In Normal Mode, only overload causes the Input Range to change. The Input Range only
moves up.
In Tracking Mode, the Input Range moves up for overloads and down when the signal
falls below half scale. Some signals, such as low frequency noise, can cause the Input
Range to oscillate. Do not use Tracking Mode in these cases.
Auto Range responds to all frequencies present at the input (except those attenuated by
AC coupling or the anti-aliasing filter), not just those within the measurement span.
Command: I1AR (?) {i}
Ch2 AA Filter
Selects the Anti-Aliasing Filter for the Ch2 input [Off, On].
The anti-aliasing filter should generally be left On. Frequency domain measurements may
have spurious alias signals if the filter is Off.
For time domain measurements involving square waves or impulses, removing the filter
can remove ringing and improve the accuracy of the time record.
The specifications apply only if the filter is On.
Command: I2AF (?) {i}
Ch2 A-Wt Filter
Select the A-Weighting Filter for the Ch2 input [Off, On]. The AWt indicator at the top
of the screen shows ‘AWt’ in bright whenever the A-Weighting filter is On.
The A-Weighting filter simulates the hearing response of the human ear and is often used
with Octave Analysis measurements. The input A-Weighting filter conforms to ANSI
standard S1.4-1983.
A-, B- and C- Weighting functions are also available as operators in User Math functions.
Command: I2AW (?) {i}
Ch2 AutoRange
Select the AutoRange Mode for the Ch2 input [Normal, Tracking]. This mode only
applies when Ch2 Auto Range is on.
In Normal Mode, only overload causes the Input Range to change. The Input Range only
moves up.