Coherent and Incoherent

[kiarash]

Hello

For my thesis I need to now the coherence between two signals. and in the attached article

I highlighted thoes equations that I am going to use. but up to now I could net figure out

how can I build Cross Power Spectrum which is used for coherence.(I have also attached

my vi prgram).( I will also attach my real data (which are pressure vs time for 8 channels

in case you want to check)

PS. I have read those former posts about cross power spectra but it could not help

however I attched that related VI.

Thanks ever so much for your help.

[Jennifer_R]

Hi kiarash,

I'm not familiar with coherence, but it seems like the Spectral Analysis VIs give you the ability to calculate that.  It looks like "Power Spectrum.vi" and "Cross Power.vi" or "Cross Power Spectrum.vi" can be used to implement the equations you highlighted.  The Help for "Cross Power.vi" explains that the Complex Conjugate can be taken to match the definition in the article you attached.  If you are using LabVIEW 8.5, another option is to use the "cohere" MathScript function.