ETAS
4 Calculated Signals
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.
MDA V8.6 – User Guide
67
Summary of Contents for MDA V8.6
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