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Asked by mohamed al-asklany on 22 Mar 2012

if i have a simulink model and the output of low pass filter is sin signal with certain frequency if i want to know this frequency and display it on a screen what should i do? remark simulation model time is (inf.)

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Answer by K E on 22 Mar 2012

I would output the signal to the workspace and calculate the frequency from within Matlab; here is an example approach. You could use Matlab to start your simulation too using the sim command, and afterward plot the spectrum that you calculate.

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K E on 26 Mar 2012

You first need to export the simulation time and signal that you want to analyze from Simulink to Matlab using the 'ToWorkspace' block. Once these variables are in the Matlab workspace, set t equal to your simulation time variable and x equal to your simulation signal (for example position). Once you have t and x in your Matlab workspace, follow the example (http://www.mathworks.com/products/matlab/demos.html?file=/products/demos/shipping/matlab/fftdemo.html) to obtain freq and Pyy. Then you can find the peak using the code that I supplied earlier:

Pyy1 = Pyy(1:128) ;

frequencyOfBiggestPeak = freq(Pyy1 == max(Pyy1)) ; % Hz

mohamed al-asklany on 27 Mar 2012

my simulink model time is inf

how i can import data from simulink in inf tim?

K E on 4 Apr 2012

You could decide how much time you would need to get a good estimate of the frequency (for example, 30 periods of a 10-second sine wave would be 300 seconds), then put an event listener (http://www.mathworks.com/help/toolbox/simulink/slref/add_exec_event_listener.html) in your model that would output the results to the workspace at 300 seconds.

Answer by Sivakumaran Chandrasekaran on 24 Mar 2012

I think you can use the option named display which is available in sink block.. I am not sure also whether this will work or not.

Regards, Siva...siva@sdatech.in

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