Owner manual

5.6 Method Specifications
746 VA Trace Analyzer / 747 VA Stand
5-132
Parameter Range; Default value / Meaning
U.width max (U.width min)...400 mV; 200 mV
Maximum peak width
Maximum peak width for the assignment of a peak or a wave to a
substance. The peak width aU.width estimated in a first approxima-
tion must be smaller than U.width max for the substance to be
recognized (see adjacent diagram and section 6.6).
I.threshold 100...5000 pA; 200 pA
Limiting current value
Limiting current value for the assignment of a peak or wave to a
substance (for all measurement modes with the exception of
PSAMODE). With the aid of the 1
st
derivative of the peak curve (or the
2
nd
derivative of the wave curve), the difference ∆
minmax
is multiplied
with an empirical factor f
MM
dependent on the measurement mode to
determine the estimated peak height approx.peak. This estimated
value must be larger than I.threshold for the substance to be
recognized (see also section 6.6).
With non-gaussian shaped peaks, the peak height approx.
peak estimated from the derivative can differ greatly from
the actual peak height I.peak. It may be necessary to
modify I.threshold for the results to be displayed or
suppressed in the desired manner.
aU.width
U.width min
U.width max
U.verify ± U.tol
aU.peak
approx.peak =
aU.max aU.min
I.threshold
I
dI/dU
U
U
The substance recognition is
based on the recognition
parameters specified for the
individual substances. The
following conditions must be
met for a detected peak to
be assigned to a substance:
1. aU.peak =
U.verify ±± U.tol
2. aU.width > U.width min
aU.width < U.width max
3. approx.peak >
I.threshold
∆
minmax
∆
minmax
× f
MM
estimated
gaussian
peak