tracking filters

[ilter]

Hello,

I want to use tracking filter methods but I have no access to a device, so I need to use software algorithms. I made a search on tracking filters but it did not give me much either. I read on http://sine.ni.com/csol/cds/item/vw/p/id/187/nid/124100 that some people made this already but I need some more explanation.

I am desperate for any help and an example VI.

Thank you very much in advance...

ilter

ps.I have a data signal that the frequency is slightly changing. I used bandpass filtering before tone measurements but it was not sufficient enough. I need accurate frequency information.

[Daniel_E]

What do you mean by tracking filters?  What is that you are trying to do?  What is the end goal?

[ilter]

Hello,

I think I made a mistake to post it here. I was suppose to post it in Labview forum. I am sorry I did not know how to delete it.

I am looking for a Labview code that will extract frequency from a noisy data data stream that looks like a sine wave. I am monitoring vortex shedding behind bluff bodies. I need a PLL or tracking filtering code to extract the frequency since it is slightly changing. I do not have access to a an external device to do it, so I am looking for a code to do it.

Thank you.

[Daniel_E]

Why don't you just use a software filter?  Look at the filter express VI (Functions >> Express >> Signal Analysis >> Filter).  This does low pass, high pass, stop band, pass band, smoothing, and maybe a few more.  You will have to look at it.

If this doesn't work, I believe this is a toolkit for LabVIEW that provides a lot more functions for this.  https://www.ni.com/en/shop/labview/select-edition.html.  Read the manuals for more information.  Look specificy at the Joint Time Frequency Analysis Toolkit.  It is design to find signals of varying frequency as you are mentioning.

Also, there may be a different toolkit that will work in these. 

Hope this helps!

Dan

[ilter]

Thank you for the information.

I will work on it.

ilter