How to add noise in transfer function

I have a system and i wrote a code for transfer function like tf(num,denum) but i want to add noise in this transfer function how can i add this?

Answer 1

[KL]

I would suggest you to create a transfer function for the disturbance, say G_disturbance, and add this to your transfer function, say G_plant, using the '+' operator.

G_out = G_plant + G_disturbance;

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[Toby Russell]

Hi, How would I specifiy that the disturbance should occur at 40 seconds using this method?