Compare waveforms using CrossCorrelation.vi

[Gary_H]

Hi,

I intend to compare 2 clock frequencies which deliberately vary in frequency value, to ensure they are not correlated, i.e. unable to trigger a scope off one clock to view the other clock.

I think that the CrossCorrelation.vi would be useful for this purpose. Having tried a few tests with simple sine wave inputs, I'm unsure of how to interpret the results.

I thought by using identical and dis-similar inputs that a I would be able to derive a test, but am unable to explain the vi output.

Does anyone have any experience using cross correlation and where I might get basic explanations on how to interpret the results.

Thanks,

Gary.   

[Josh_E]

Hi Gary,

Below is a link to an example VI that uses CrossCorrelation.vi to find the time delay between two identical signals.

https://decibel.ni.com/content/docs/DOC-12657

Both signals are input to the CrossCorrelation.vi. This then outputs an array containing the cross correlation data. Any large peak in this data will indicate a sample delay.

If you need some help understanding your own code, feel free to post it up here.

Kind regards,

[johnsold]

Gary,

Perhaps it would be easier to use a Fourier transform or Extract Single Tone Information.vi to check the frequencies.

Lynn