Finding the Trasfer Function !

There friends,

I have input and output signals of a biological system and it is needed to estimate its Transfer Function. Then the Transfer Function could be used for producing new signals.

So, I have used the "tfestimate" command in MATLAB and the estimated result has been used in "yulewalk" command for designing a filter. The filter suppose to works similar to our biological system. For finding that this system is working properly or not, I tested it with the same input's data but the output was not similar to the biological output that I have.

I have copied the code below. It will be my pleasure to have your idea about it or any new idea for estimating the transfer function.

%-------------------------------------

[TF_Magn_rs_rr,TF_Freq_rs_rr]=tfestimate(rs,rr,[],[],2048,1/Ts);

max_freq=max(TF_Freq_rs_rr); max_magn=max(TF_Magn_rs_rr);

% For yulewalk, the frequency should be between 0 and 1. So frequency is divided by MAX of frequency and the same for magnitude.

[b,a]=yulewalk(10,TF_Freq_rs_rr./max_freq,TF_Magn_rs_rr./max_magn);

rr_new=filter(b,a,rs);

%-------------------------------------

Answer 1

[Rajiv Singh]

If you have System Identification Toolbox, you could try directly estimating the transfer function (b/a) using input/output data; see:

http://www.mathworks.com/help//ident/transfer-function-models.html