Stanford Research Systems SR785, Operating Manual And Programming Reference

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User Math Functions 1-53
SR785 Dynamic Signal Analyzer
Use the knob to adjust the Span to 6.4 kHz and
press [Enter]. Set the Span to display the filter notch at 1 kHz.
The top display (A) is measuring the filter input
and should show a fairly flat spectrum. The bottom
display (B) is measuring the filter output and
should show a deep notch.
Both displays are measuring absolute signal levels.
6. Press [User Math]
Select the User Math menu.
Press <Function> Choose one of the five user functions available in
the FFT measurement group.
Use the knob to select (FFTUsrFn2) and press
[Enter]. Select Function2 to edit.
Press <Edit Fn> Show the Edit Function menu.
Press <Operands> The display shows the available operands for this
function.
Use <Operands> and <Operations> to switch the
display between operands and operators.
Use the knob to highlight the desired box and press
[Enter] to insert the selection into the function
string at the top of the screen.
Use the knob to highlight FFT(2) and press
[Enter]. Choose FFT(2) as the first operand. This is the FFT
of Ch2 and is identical to the normal measurement.
We are going to define a transfer function
(FFT2/FFT1).
As soon as the operand is entered, the display
switches to show operations.
Use the knob to highlight / (divide) and press
[Enter]. Choose the divide operation next.
The display switches back to operands.
You can choose another operation instead by
pressing <Operations>.
Use the knob to highlight FFT(1) and press
[Enter]. Choose FFT(1) as the denominator of the transfer
function.