Lambda SR1, Operation Manual, Page: 98 / 317

SR1 Operation Manual 98
© 2014 Stanford Research Systems
2.3.8 Settling Panel
While in sweep mode SR1 requires all measurements to "settle" before adding them to the sweep.
Settling insures that the variability for the measurement, whether intrinsic to the measurement or due to
transients arising from the sweep, is reduced to a predetermined level. Each measurement can have a
different settling profile, each characterized by a precision, number of points, profile, threshold, and
delay.
Precision
The precision parameter sets the amplitude scale for what is considered a settled measurement. If the
value of the most recent measurement is
y , then another measurement is considered to be within
tolerance if its value falls in the range of y×(1 ± precision) . Tightening the precision window increases
the precision of the final sweep data at the expense of having to possibly wait longer for a settled
measurement .The "correct" value of the precision depends on the measurement and application and
can usually only be determined by experimentation– the tight tolerance that might be appropriate for
measuring the flatness of a filter passband with sub-dB precision is probably too restrictive for broadband
noise measurements.
Profile
The settling profile, along with the value of nPoints, defines an algorithm which determines whether an
measurement is settled. Each of the settling profiles is described below:
Settling Profile Description
None No settling is performed when this profile is selected. The most recent
measurement is always considered settled and added to the sweep
Exponential In exponential settling the most recent measurement point is compared with the
last nPoints-1 previous measurements. For the measurement to be considered
"settled," the previous point must be within tolerance of the current point. The 2nd-