Transfer function with tfestimate

Hello,

I am trying to calculate the transfer function from a self-created filter. I want to try this using a noise signal which i will filter. Blue is x, red is filtered x.

 x = randn(16384,1);

This filter has the properties:

filter fs = 8000.

Now i want to calculate the transfer function which i have created for the filter by using the function: tfestimate and compare the phases from the filter transfer function and estimated transfer function. So lets say the orginal signal is called x and the filtered signal is y.

The problem is when i use tfestimate the output data is not correct.

[Txy,f] = tfestimate(x,y,1024,[],[],fs)
figure
semilogx(f,mag2db(abs(Txy)))

If someone could help me, it would be appreciated.

[Niels Barella]

Update: So now i use a frequentie cap-off of 100 Hz.

I had the frequency wrong(fs)..... I guess i need a rubber duck ;D.