How can I create an impulse (delta) signal in Simulink?

I could see several uses for a pulse function in Simulink. For example adding a defined amount of chemical into a mixing tank volume instantaneously, and having delayed mixing in the tank. calculating output concentration is a common chemical enginering task.

I get that takting the derivative of the step function will depend on the sample time, and I wonder why the Dirac function is not available in the Simulink function library?

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Answer 2

Chul-Goo Kang 2019-12-28

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Use step input and multiply s in the transfer function of the next block.

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Henry Davies 2020-3-30

Can you please explain what you mean by this?

SAMSARA NIRVANA 2021-12-29

esta derivando

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Answer 3

Fangjun Jiang 2018-5-4

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编辑：Fangjun Jiang 2018-5-4

From the note of impulse():

Note: In discrete time, impulse computes the response to a unit-area pulse of length Ts and height 1/Ts where Ts is the sample time. This pulse approaches the continuous-time Dirac impulse delta(t) as Ts goes to zero.

So you will construct a pulse of width as Ts and height as 1/Ts.

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Alessio Conte 2018-5-5

Hi, thanks for your answer. Not sure to have understood... do you mean that a rectangular signal whose base is Ts and height is 1/Ts is the equivalent of a delta impulse signal? I attach an image of what i mean

Fangjun Jiang 2018-5-7

That is correct. When Ts->0, the pulse becomes the theoretical delta (the impulse).

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Answer 4

Alessio Conte 2019-3-29

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Yes you're right actually...I was just curious of doing what we have seen in classe but actually doesn't make sense.

Thanks!

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Answer 5

Hiromasa 2024-6-14

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Thank you for your question.

One way to create an impulse signal is to use Hit Crossing block. (https://www.mathworks.com/help/simulink/slref/hitcrossing.html)

As shown below, Hit Crossing outputs an impulse signal of magnitue 1. The gain block after the Hit Crossing amplifies the signal by the factor of 1/t where t is a discrete time step for the system.

Hope this information helps.