Can Labview perform wavelet coherence?

[Tredude]

Hello all, Thank you in advance for time and advice.

I am very interested in performing Wavelet Coherence analysis on some data I've collected during my PhD. In short, I wish to see the coherence between to time-varying signals as a function of both time and frequency. I understand that Labview is capable of performing JTFA using Short FFT's and Wigner-Ville analyses, but I'm leaning more towards the contemporary technique of determining the Wavelet Coherence Spectrum. 

Labview's Wavelet toolkit is more than adequate to perform a continuous wavelet transform on my data separately, but has anyone had any success with performing the complex mathematics on the Wavelet co-efficients (output from the wavelet vi's) to produce the cross-wavelet and wavelet-coherence time-freq. spectrum?

Thank you again!

[Ryan-C]

Hi Tredude,

I think you should be able to calculate Coherence and Cross-correlation just the same as any other data.  (Is this what you're looking for?)

For Coherence, the "Dual Channel Spectral Measurement" Express VI from the Waveform Measurements palette may be used.

For cross-correlation, there are a few options.  There is a CrossCorrelation VI under the Signal Operation palette, but other less straightforward possbilities exist in other palettes as well.

Best of luck!

[Tredude]

Thanks Ryan, however my application requires that I analyse coherence as a function of time. There appears a plethora of Matlab code that can perform this task, but I've found nothing in Labview...

Here is a link to the Matlab equivalent of what I'd like to do in Labview: http://www.pol.ac.uk/home/research/waveletcoherence/

Any thoughts on whether this could be done?

[Ryan-C]

It looks like we have explored all the options in the Signal Processing Toolkit.  At this point, since it seems you want to avoid writing the code yourself if possible, I would recommend looking into the Mathscript Runtime Module.  http://sine.ni.com/nips/cds/view/p/lang/en/nid/207268 It requires a license, but you should be able to download the evaluation software in order to try it out for 30 days if you like.  Mathscript alows you to use chunks of MATLAB code in your LabVIEW program.

[Tredude]

Cheers mate, I figured I'd end up having to use either MATLAB or use Mathscript in Labview to invoke some MATLAB code anyways. Most of the toolbox's available online for this crosswavelet/coherence analyses use the CWT toolbox for matlab, I doubt this is support natively in Mathscript? If not, can I still use a Mathscript node to run this toolbox, provided I have MATLAB installed on my computer at the same time? I'm a little unsure how that works :-S

[Ryan-C · Accepted solution]

Actually, if you use the MATLAB Script Node, which is separate from the MathScript RT Module, it actually calls the MATLAB sotware from LabVIEW using ActiveX.  So, I think that whatever MATLAB Toolbox you use should work.

See http://zone.ni.com/reference/en-XX/help/371361H-01/gmath/matlab_script_node/

Good luck and keep me posted!

[Tredude]

Now that IS cool, I'll give that a go! Fingers crossed that's just what I need! Cheers!