I need a sample vi that can plot a transfer function given zeroes and poles (It should allow the user to input zeroes and poles). It should be done in the S domain.The user should be allowed to put poles and zeroes, with frequency

[AFM]

I need a sample vi that can plot a transfer function given zeroes and poles (It should allow the user to input zeroes and poles). The user should be allowed to put poles and zeroes, with frequency. DONE IN S DOMAIN.

[chutla]

Good Evening!

I wonder if this might not be a lot easier to do in Matlab; the stock filter design toolkits do all this kind of thing. If you need the Labview interface, you can always use the Matlab function in a formula node, so it looks and feels like a Labview application. If this doesn't work for you, you might want to search the Labview code exchange database, just to see if it's been done before. However, this is probably not a weekend project, if you're starting from scratch!
Just a few thoughts!

Eric

[chutla]

Greetings again!

Just after sending you my response, my curiosity glands really got going. As it turns out, Labview has JUST the program you need. Go to this link:

http://zone.ni.com/devzone/conceptd.nsf/webmain/D09F0AE9A2044B8B86256A710048BAEF?OpenDocument#2


It looks an AWFUL lot like the equivalent Matlab console, which is actually a very good thing 🙂

Eric

[LocalDSP]

I have created a VI (LabVIEW 6.1) that does what you want. Note that the poles and zeros have to be entered correctly that is in Rad/s and typically with negative real part. The VI offers you all options for lin/log frequency axis, magnitude in dB or not, phase in Radians or Degrees etc...

The VI is written with "academic" in mind, so it is not optimized for performances but (hopefully) for clarity. I hope this will work for you.

[Sara2004]

I noticed in this VI, there are values of 100 in all the pole & zero fields, although they appear greyed out. Do these values affect the VI? I doubt it but I just want to be sure since I'm not seeing the response I expect. Thank you.

[LocalDSP]

The grayed out values of 100 just tell you that the default value of the control used inside the array was 100 (it is normally 0.00 but I may have copied the control from another VI that had default value of 100). The grayed-out values do not affect the calculation. If you want to get rid of this just replace the controls inside the array with a new default control.