3 • Operation and Maintenance
Doc. 031644-02 9/03
3-25
Step Override
In almost all cases, the step setting selected by PeakNet 6 or Chromeleon
is preferred. However, it is possible to override this setting by manually
changing the step in the PGM file or the control panel.
For example, it may be desirable to increase the step time for the 3D field
or any of the five absorbance channels. For the 3D field, the step
determines the sampling rate at which the detector stores spectra. Ideally,
the step is no smaller than the interval suggested for the rise time (see the
table in “Step”). The advantage of a larger step size is that it reduces the
amount of data stored; for example, selecting a step twice as large as that
listed in the table reduces the data file size for the 3D field by 50%.
If you select a larger step size when the average parameter is on (see
“Average”), the system response is a combination of the selected rise time
and the average of the data points between steps. If you select a larger step
size when the average parameter is off, the selected rise time is valid, but
some data points will be skipped.
Average
The average parameter operates in conjunction with the step parameter (see
“Step”).
When average is On, PeakNet 6 or Chromeleon averages the data points between
step intervals, reports that value, and noise is reduced.
NOTE The default setting for average (On) is recommended for
most applications.
When average is Off, PeakNet 6 or Chromeleon reports the data points at the step
interval. The data points between steps are skipped and noise is not reduced.
Selecting an inappropriate step setting may cause loss of sensitivity,
skipped data points, and other problems. Guidelines for overriding the
automatic selected step setting are provided for reference by
advanced users only.
If average is On and the step size is more than double the rise time,
the system response will be dominated by the step size. The system
response time is approximately the larger of a) the rise time
or
b) two
times the step size (when average is On).