Windowing in Extract Single Tone Information.vi

[aaronb]

Does anyone have any ideas in converting the built-in Labview function "Extract Single Tone Information.vi" to use Flat Top windowing instead of the default Hanning windowing? I need the same functionality this built in VI provides only I need Amplitude and Frequency (after advanced search options applied) to reflect Flat Top windowing. For context I have attached my Signal input VI which uses a DAQmx task.

[Neville D]

It seems you can't modify VI's in vi.lib anymore.. ARGGGHH!! Why does NI have to make everything more difficult with every new release?

Anyway, Open up Extract Single Tone Information 1 Chan.vi, manually build an exact copy of it using Extract Single Tone Information from Hann Spectrum.vi.

Make a copy of ma_FFT with Hanning.vi but make the WINDOW typedef constant into a Control and change from Hanning to flat top.

Stick this modified VI into the first VI and you should be done.

These are the mechanics of it, but you can only tell with actual data whether changing the windowing is going to give you "correct" results.

FYI, this VI was once available as a download from the NI website and could be modified at will. Maybe you can look there again to find an older version and that might be quicker to modify.

Neville.

[aaronb]

QUOTE (Neville D @ Mar 17 2009, 12:56 PM)

It seems you can't modify VI's in vi.lib anymore.. ARGGGHH!! Why does NI have to make everything more difficult with every new release?

Anyway, Open up Extract Single Tone Information 1 Chan.vi, manually build an exact copy of it using Extract Single Tone Information from Hann Spectrum.vi.

Make a copy of ma_FFT with Hanning.vi but make the WINDOW typedef constant into a Control and change from Hanning to flat top.

Stick this modified VI into the first VI and you should be done.

These are the mechanics of it, but you can only tell with actual data whether changing the windowing is going to give you "correct" results.

FYI, this VI was once available as a download from the NI website and could be modified at will. Maybe you can look there again to find an older version and that might be quicker to modify.

Neville.

Neville,

I am a Labview newbie and not sure what you mean by "but make the WINDOW typedef constant into a Control and change from Hanning to flat top." Could you please elaborate on this?

[Neville D]

QUOTE (aaronb @ Mar 18 2009, 08:46 AM)

Neville,

I am a Labview newbie and not sure what you mean by "but make the WINDOW typedef constant into a Control and change from Hanning to flat top." Could you please elaborate on this?

Ignore earlier advice. Changing the window constant only gives you a choice of Hanning or No windowing.

Instead: replace the Hanning Window VI with the Flat Top Window.vi like shown in the Blue Sequence below:

http://lavag.org/old_files/monthly_03_2009/post-2680-1237402388.jpg' target="_blank">

I notice you have 7.1.1. That SHOULD allow you to save the Extract Single Tone (or any other VI from vi.lib) separately to a new VI. Do this before making any changes and save to a different location so that your changes don't get erased with the next update of LV!

I have 8.6 so my changes are a lot more work, plus you won't be able to open the VI anyway..

N.