perform a bilinear transform without Matlab or MathScript modules

[DianeS]

Hi all,

I've been poking around the forums all morning and haven't found what I'm looking for.  I've found information, mind you, but it seems I'm not smart enough today to put all the pieces together.  So I'm just going to ask, and hope for the best.  Maybe someone can point me in the right direction...everything's blurring together at this point.

Is there a relatively straightforward way to perform a bilinear transformation in LabVIEW without the use of either Matlab or MathScript?  I don't have access to either one.  If there is a built-in LabVIEW function, I'm not finding it.

The MathScript code looks like this:

w3 = 2*pi*f3;

B = [1/w3 1];

w4 = 2*pi*f4;

A = [1/w4^2 1/Q4 1];

[b,a] = bilinear(B,A,fs);

Help?

Thanks!

d

[Darin.K · Accepted solution]

Since you are using the transfer function representation you have to do the transformations to and from state space representation and perform the bilinear transform in between.  Normally this is hard to do from scratch, but LV has the Characteristic Polynomial.vi built in so it is pretty easy (once you get the formula right).

Statespace <-> Transfer function VIs I have used before so I think they are correct.  Bilinear transform was just tossed together using the help from mathworks.

[DianeS]

Darin, you are awesome!  Thank you!

[ed_Z]

Darin K. and DianeS,

I modified Darin K's code slightly. 

Some Labview users may find the new function s_to_z_Bilinear_Transform.vi a little bit easier to use. 

Edward Z.