zero crossing of noisy signal

[scientist]

I need to compute the zero crossings of a noisy waveform. Can anyone help?

[jcrooke]

Please, be more specific. Do you want to count crossings that may be due to noise, or do you want to discriminate against the noise and count zero crossings from a band-limited signal?

[JuanCarlos]

Hi,

If you know the frequency range where the signal comes in you can do some bandpass filtering to eliminate the noise then you can use the "in range and coherce" VI to create a zero crossing algorithm with histeresis. If you expect periodic zero crossings you could use the "get ton information" VIs to calculte the main frequency and having the total duration you can calculate the number of zero crossings.

Here is a very basic example of zero crossing that I've found; I hoe this helps you get started.

Regards,

Juan Carlos
N.I.