frequency mesurement of a square wave
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hi I want to to measure the frequency of a square wave with simulink , do anybody know how to do this? thanks
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Image Analyst
le 22 Fév 2015
Modifié(e) : Image Analyst
le 22 Fév 2015
I don't have Simulink but I think you can use a MATLAB block in it where you run MATLAB code. If so, then just threshold the signal and use find()
signal = [0 0 6 6 6 0 0 6 6 6 0 0 6 6 6 0 0]
halfMaxValue = 0.5 * (min(signal) + max(signal)) % Halfway between 0 and 6.
highSignals = signal > halfMaxValue
diffSignal = [0 diff(highSignals)]
diffSignalIndexes = find(diffSignal == 1)
period = diffSignalIndexes(2) - diffSignalIndexes(1) % Distance between first two pulses.
In the command window:
halfMaxValue =
3
highSignals =
0 0 1 1 1 0 0 1 1 1 0 0 1 1 1 0 0
diffSignal =
0 0 1 0 0 -1 0 1 0 0 -1 0 1 0 0 -1 0
diffSignalIndexes =
3 8 13
period =
5
9 commentaires
Image Analyst
le 24 Fév 2015
Your signal doesn't quite look right. The plot seems to show it going high around element 43 or 44 but your signal variable shows it going up around element 42.
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MoeIsKing
le 24 Juin 2018
Modifié(e) : Image Analyst
le 24 Juin 2018
If i run:
highSignals = signal > halfMaxValue
over my signal i get:
"Error using horzcat
Dimensions of arrays being concatenated are not consistent."
What did i wrong? My "highSignals" type is "2002x1 logical" after I run:
highSignals = volts > halfMaxValue ;
halfMaxValue is 12 and volts comes from a scope (light bar) and is imported as csv into "2002x1 double"
1 commentaire
Image Analyst
le 24 Juin 2018
It looks OK to me. What I don't understand is how you could execute the line to create highSignals successfully as a 2002 by 1 vector, and yet still have an error thrown? In my experience if an error is thrown, you will not get the result put into the output variable. Can you explain that? Exactly what line of code are you executing when the error is thrown?
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