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For getting the peak-to-peak(P2P) value, our system also use detector. At first, the positive and
negative peak values are calculated, and then we can get P2P from the difference of positive P2P and
negative P2P. The positive peak values are calculated from the positive signal and the negative peak
values are calculated from the negative signal. [Fig. IV-1-4] and [IV-1-5] shows how to calculate P2P
from signal.
[Fig. IV-1-4] A Case of Small Release Time
Constant
[Fig. IV-1-5] A Case of Big Release Time
Constant
1. 3 Calculation of the Maximum of Signal (Max. Detector)
Peak Values are decreased with the release time constant as time goes. If you want to observe the
peak value(or maximum) during measuring, you have to use the maximum detector. You can’t
observe the peak value with peak detector. The value is found from the signal during the integration
time. For example, suppose that the integration time is 5sec. This system finds the maximum value
from time signal with 5sec and then saves and displays it to file at every 5sec. the integration time is
shown as
T
at [Fig. IV-1-1]
1. 4 Integrator
The theory of discrete integrator is classified into 3 types. There are Trapezoidal, Forward Euler
and Backward Euler. Integrator is written like below in the
s domain
−
:
( )
1
H s
s
=
<Eq. IV-1-4>
After this equation is rearranged with the bilinear Z Transform method, the integrator is written as
below in the
z domain
−
:
1
1
2 1
1
z
s
T z
−
−
−
=
+
<Eq. IV-1-5>
( )
1
1
1
2 1
T z
H z
z
−
−
+
= ⋅
−
<Eq. IV-1-6>