Owner manual
6 Data processing and evaluation
746 VA Trace Analyzer / 747 VA Stand
6-12
• Base points
Selection of the base points is decisive for the determination of all baselines.
In the automatic determination of the base points (dU.front = auto and
dU.rear = auto), these are determined from the results U.max, U.min, and
U.peak (see section 6.6) obtained in the recognition of peaks or waves. For
this, the two differences Uw.front and Uw.rear (which are identical only for
symmetrical peaks) are multiplied by the empirical factor f
G
defined using
ideal gaussian-shaped curves such that the height at the base point is 5% of
the maximum peak height. In the case of baselines with Type = linear or
Type = AC2..., this factor is multiplied by 0.8, i.e. the base points are nearer
the peak maximum than baselines with Type = polynom or Type = expon..
U.width
I
U
dU.front dU.rear
Uw.rearUw.front
U.minU.max
U.peak
Uw.front = U.peak - U.max
Uw.rear = U.peak - U.min
U.width = Uw.front + Uw.rear
dU.front = Uw.front × f
G
dU.rear = Uw.rear × f
G
• Slopes
Equally important as the selection of
base points is that of the associated
slopes. In the automatic determination
of the slopes (S.front = auto and
S.rear = auto), these are calculated
from the smoothed curves at the loca-
tion of the base points. The slopes are
standardized so that the following al-
ways holds:
S = 0 horizontal slope
S = 1 diagonal slope
S = ∞∞ vertical slope
S
=
0S
=
0
S
=
∞∞
S
=
-1 S
=
1
• Overlapping
Two peaks which overlap can mutually
influence each other to an extent which,
depending on the degree of overlap-
ping, can impair or even completely
prevent their evaluation. With the 746 VA
Trace Analyzer, the peaks are automati-
cally investigated for any overlapping
with neighboring peaks. The position of
the base points Ur1 and Uf2 is used
as a criterion for determination of the
overlapping:
∆
U.peak
U.width1
U.width2
Uf2
Ur1
Uf1
Ur2
Ur1 > Uf2 Overlapping at the rear of the 1
st
peak
Uf2 < Ur1 Overlapping at the front of the 2
nd
peak