Dear Harald,

Thank you for your answer.

It is a big system with multiple inputs and outputs in state space form.

And it gives 16 transfer functions.

I did try to represent them using integrators and summation nodes, but it does not work.

I also tried to represent the state space equations directly with an integrator and gain blocks, but then the response stays 0.

Dear Zoe,

I will try to give conceptual answer that may help you find a solution to your problem. You can use normalized filter functions where in case of low pass filter the frequency is normalized by dividing every frequency to the 3-dB cut off frequency wc. While the amplitude is normalized by dividing it the highest gain in the pass band.

Such normalized filters preserve the shape of the frequency response while one can scale the cut-off frequency. This is the property which is required by you.

There are standard filter functions: Butter worth, chebychev, elleptic and Bessel.

You can find then in the book of filters and also in Sumilink.

Only the elliptic filter contains zeros, which may be put in the stop band with the required number.

Best wishes

Dear Abdelhalim

It was indeed helpful.

Thank you.

Please look at the book (Linear Time-Invariant Systems)

by

Schetzen

from

Northeastern Universiy

in

Boston, MA

Thank you