Stanford Research Systems SR785, Operating Manual And Programming Reference

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Swept Sine Frequency Menu 4-17
SR785 Dynamic Signal Analyzer
Measurements which differ by more than the Faster Threshold (on EITHER channel) but
less than the Slower Threshold (on BOTH channels), maintain the present sweep speed.
The number of points skipped remains the same in this case.
If the marker position is displayed with a ‘?’, the point has not actually been measured
but is interpolated from actual measured points. The measurement of these points was
skipped due to sweep Auto Resolution.
Command: SARS (?) d {, i}
Number of Points
Set the Number Of Points [10..2048]. The points are in a Linear or a Logarithmic
progression as set by the Sweep Type.
If the Number Of Points is changed during a sweep, the sweep will be reset.
A sweep with a large number of points can detect narrow features. A sweep with a small
number of points will take less time. In order to save time while maintaining a high
resolution, use Auto Resolution.
Command: SNPS (?) d {, i}
Maximum Step Size
Set the Maximum Step Size for Auto Resolution frequency sweeps [2..256].
When Auto Resolution is On, each successive time the Faster Threshold condition is met
(on BOTH channels), the frequency step size is increased until the Maximum Step Size
is reached. This sets the maximum speed at which the sweep will continue until the
Slower Threshold is exceeded.
Generally, this number should not exceed 5% of the Number Of Points in the sweep.
Command: SSKP (?) d {, i}
Faster Threshold
Set the Faster Threshold [0.01..3 dB].
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).
Measurements which differ by more than the Faster Threshold on EITHER channel, but
less than the Slower Threshold on BOTH channels, maintain the present sweep speed.