Frequency Response Function vi...no data from coherence function.

[Adzel]

Hello, I am using the Frequency Response Function vi to generate magnitude, phase, and coherence. The vi is generating the correct mag and phase (I checked against an o-scope) but it does not create a coherence value (typically it will fall from zero to under 1).

Has anyone seen this problem before in this vi?

Thanks!

Adzel

[Ankita]

Hi Adzel,

Coherence values typically range from 0-1. Are you not seeing this behavior? Are you getting a coherence value of 1 at all times ? If that is the case then it is possible that you are not supplying enough stimulus and response readings. Please refer to this link for more information.

Also if you like, you can refer to the Frequency Analysis of a Filter Design VI in the labview\examples\measure\maxmpl.llb directory for an example of using the Frequency Response Function (Mag-Phase) VI.

Hope this helps.

Ankita