ETAS MDA V8.6 User Manual page 67

ETAS
MDA V8.6 – User Guide
As a frequent use case is to ignore samples for a calculation,
there is a separate function to assign the No Value state to
samples.
In contrast to the former definitions, you must define the con-
dition in a way that it is clear which samples shall be excluded.
Condition for speed range to be excluded: (Speed <= 40)
Or (Speed > 80)
(In contrast to the True condition above)
Function to assign the No Value state for specific samples
(outside 40 - 80 km/h):
SetNoValueStatus ( Speed, ( (Speed <= 40) Or
(Speed > 80) )
This is equivalent to
Selected_Samples = (Speed > 40) AND (Speed <=
80) ? Speed : NoValue (Speed)
In this case, the NoValue (signal) causes that the original signal
value of Speed is kept, but gets the No Value flag assigned.
This selection of samples for the speed signal can be used as
input for e.g. an Average calculation (since start of the recording).
Average_Speed = Accumulate_Prefix_Average (
Selected_Samples )
2. The No Value function can also be used to suppress drawing
samples in an oscilloscope, for example for the distance cal-
culation mentioned above.
Interrupted_Distance_Curve = (Speed > 40) AND
(Speed <= 80) ? Distance : NoValue (0)
With Distance = [Factor *] Accumulate_Prefix_
Integral ( ( (Speed > 40) AND (Speed <= 80) ) ?
Speed : 0 )
Note: Although the calculation
Accumulate_Prefix_Integral ( ( (Speed > 40) AND
(Speed <= 80) ) ? Speed : NoValue (0) )
would also show a curve with the same gaps as the Inter-
rupted_Distance_Curve signal, the result would not be as
you might expect it.
This is an effect of the Integral function: If there is no sample (or
a sample with No Value flag), the integral uses the last available
sample value for the whole time range until the next sample is
available.
4 Calculated Signals
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