Stanford Research Systems SR785, Operating Manual And Programming Reference

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4-16 Swept Sine Frequency Menu
SR785 Dynamic Signal Analyzer
Repeat
Select the Sweep Repeat Mode [Single Shot, Continuous].
In Single Shot mode, the measurement is paused at the completion of the sweep and the
source ramps off.
In Continuous mode, the measurement is repeated at the completion of each sweep. The
source moves immediately to the Start frequency and begins the sweep again. Data from
the previous sweep is preserved on the display and can be examined with the cursor.
Command: SRPT (?) d {, i}
Type
Select the Sweep Type [Linear, Log].
Linear sweep computes the measurement points in a linear progression from the start to
the stop frequency. Choosing linear sweep also sets the X axis to linear.
Log sweep uses a logarithmic progression of points from the start to the stop frequency.
Choosing log sweep also sets the X axis to logarithmic.
Command: SSTY (?) d {, i}
Auto Resolution
Select Auto Resolution [Off, On].
If Auto Resolution is Off, all points in the sweep are measured.
Auto Resolution On allows the sweep to skip points if sequential points do not vary by
more than a specified amount. Auto Resolution is specified by three parameters, the
Faster Threshold, the Slower Threshold and the Maximum Step Size. These parameters
can only be adjusted when Auto Resolution is On.
Auto Resolution examines the results of successive measurements. If the newest
measurement is within the Faster Threshold of the previous measurement (for BOTH
channels), then the sweep will take larger steps, skipping frequency points. Each
successive time this threshold is met, the step size is increased until the Maximum Step
Size is reached. This speeds up the sweep in regions where the response is flat (varies
less than the Faster Threshold).
If a measurement differs from the previous measurement by more than the Slower
Threshold (for EITHER channel), then the sweep returns to the previously measured
point and moves to the very next frequency point in the sweep (with no skipping). The
sweep continues from this point, speeding up if allowed and slowing down when
required. This ‘fills’ in skips in the sweep which vary by more than the Slower
Threshold.