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. 

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