System Identification Tool fails?

Hi,

I have a System with a sine-sweep as input. The measured output is as well as the input in time domain.

Sweep ---> H(z) ---> Output

The discrete H(z) is calculated by the System Identification Tool very good.

But what I am interested in in is the INVERSE transfer function of H(z).

I want the discrete G(z).

Output ---> G(z) ---> Sweep

For that i switched the Sweep to the Output and the real output is gonna be my input for the model. But the System Identification Tool can't calculated a satisfiying solution.

Does anyone know an answer?

[Star Strider]

Without the data, it is not possible to determine the reason. The inverse transfer function may not exist (its being improper is usually the reason). One way to test that is to use a state-space representation, then see if an inverse of it exists:

so calculate:

I suspect that is singular, or if not, close to it.

Answer 1

[Christoph Thale]

Anyone?