Discrete Average on Simulink

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Marco Minneci
Marco Minneci on 22 Feb 2023
Commented: Marco Minneci on 20 Apr 2023
Hi, I have a problem in Simulink. I should obtain the average value of a signal but I should keep this average value for the next 600 steps time. During these steps the output value is constant and it has to be updated each 600 new steps. How can I do this? Thank you so much.
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Marco Minneci
Marco Minneci on 23 Feb 2023
The output from 1200 to 1800 should be the average of the input from 600 to 1200. The key question is how can I obtain this in simulink.

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Answers (2)

Fangjun Jiang
Fangjun Jiang on 23 Feb 2023
Edited: Fangjun Jiang on 23 Feb 2023
See attachment. Use "window length" of "6" instead of "600" to illustrate.
The build-in "Moving Average" block (it requires "DSP System Toolbox") seems like the right one to use. Need to debug further to see why the "initial condition" of the "Rate Transition" block (It behaves as a zero-order hold block) didn't take effect.
I also tried to use a MATLAB Function block to implement this. It is not too hard as long as you have a clear mind of the logic.
"InitialValue" and "WindowLength" is set in base workspace using the model PreLoadFcn callback.
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Marco Minneci
Marco Minneci on 20 Apr 2023
Hi, I have another problem on the same topic. I would know if it is possible to have this particular structure but with a variable step size (the size for the solver of simulink). Thank you in advance.

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Paul
Paul on 23 Feb 2023
Edited: Paul on 23 Feb 2023
If I understand the question correctly .....
Use a Discrete FIR Filter block to maintain a running average of 600 samples. Set the Sample Time parameter to the desired value or leave as -1 for inherited if the input signal is already at the desired sample time.
Connect the output of the Discrete FIR Filter block to the input of a Rate Transition Block. Set the Output Port Sample Time Options to Multiple of input port sample time. Set the Sample Time Multiple parameter to 600.

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