Cross Correlation vi. How does it work

[Mark Mutton]

How does the cross correlation vi. Work?  Is there an effect of amplitude? For example if I have a reference signal that i am passing through as my X That is identical for all correlations but my amplitude on y varies. The signals are similar in shape, so they should be ideal candidates for correlation. I am finding thorough experiments that as my amplitude on y changes so do my results. Why is this and is there a way in software to fix this or do i have to have someone man the controls.

[johnsold]

Mark,

The help for the Cross Correlation.vi shows the formula as: R(t) = Integral(x(tau)*y(t+tau)*dt)

Thus, the value is sensitive to the amplitudes.

To get around variations in the y amplitudes, normalize the y array to +/-1 before sending it to the correlation VI.

Lynn