Tapped delay function with varying size in Simulink
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Swati Poduval
on 20 May 2020
Commented: Vu Hoang Thang Chau
on 18 Jan 2024
Hello
I wanted to know if there a way to give the "Number of delays" externally in the tapped delay function.
My idea is, the user should be able to connect an input port and this port gives the number of delays that the tapped function needs to have. So as to make it dynamic and not static where I set the number of delays during development phase itself.
(Setting parameters of the tapped delay function in simulink externally)
Thanks![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/295108/image.png)
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/295108/image.png)
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Accepted Answer
Jonas
on 26 May 2020
Hi Swati
I have tested a few things and I don't think it is an easy problem to solve.
I have personally never used the Tapped Delay - and I don't know why you need it in your specific application - but the issue I see is that the output dimension depends on the number of delays you put into the dialog. If you enter 4, then the signal dimension of the output is 4. If you chose 7, the signal dimension if 7. That's why it is very difficult - I believe even impossible - to provide it as an input port.
One thing I was thinking about, is that the Unit delay block can have the delay length as an Input port. You can change this during simulation. But it will only output the input signal with the defined delay, it will not provide all other signals such as the Tapped Delay block does.
With kind regards,
Jonas
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More Answers (1)
Oscar de la Hoz
on 27 Nov 2022
Hi Swati,
Try to use one variable in "Number of Delays" field.
In my case, I wanted "Number of Delays" to be equal to Simulation Time. So first I wrote the variable:
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/1209453/image.jpeg)
After that, create a Matlab function externally, with the algorithm of your input value and use Callbacks (in Model Explorer) to run the Matlab function (in my case, the variable was created when the model was run, so I used the function in InitFnc):
Matlab Script saved as "StopTime_InitF"
StopTime_1 = double(0);
My_model = get_param(0, 'CurrentSystem');
stop_time_as_str = get_param(My_model, 'StopTime');
StopTime_1 = str2double(stop_time_as_str);
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/1209458/image.jpeg)
The function will modify "StopTime_1" variable in Model Workspace just before running the model.
Then, "Number of Delays" has been modified externally.
I hope you can adapt this to your case.
Regards,
Oscar.
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Vu Hoang Thang Chau
on 18 Jan 2024
Hi Oscar,
I have a similar issue and worked this out before.
I think this mostly works if you stay with simulation or C code generation.
My application requires HDL generation and it is a pain to regenerate this all over again all the time using this method.
I'm using the Memory and Selector method as above.
Regards,
V.
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