Chapter 5 Web-Based Operations
112 Lynx II DSA User's Manual - 7096089
Please note that with the Slow Discriminator Mode in Manual, excessively lowering the
Manual Slow Disc (%) setting will defeat noise discrimination, resulting in excessive
storage of noise events into the lower area of the spectrum and possibly causing
undesirable operation.
Stabilizer
The Spectrum Stabilizer applies only to PHA spectrums. The stabilizer algorithm in the
Lynx II DSA is based on similar implementations of spectrum stabilization in other
CANBERRA MCAs, where two user-defined regions of interest or windows are used to
monitor the count rate and control the stabilization.
The stabilizer algorithm periodically monitors the count rate at the lower window (Clow)
and the count rate at the upper window (Chigh) and then calculates the ratio between the
two as:
Rtemp = Chigh /Clow
Rtemp is then compared against a previously-established reference ratio (Rref) and if a
significant difference is found, a correction value is applied to the signal gain to
compensate for the drift.
User settings for the spectrum stabilizer algorithm include the width of the sampling
windows, a centroid channel, the spacing, a reference ratio, and a correction divider. The
relationship between the windows, spacing, and centroid settings is shown in the figure
below.
Figure 56: Relationship Between Stabilizer Functions
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