Can JFTA toolset provide phase info?

[Chris_12345]

The JFTA toolset provides a 2D set of points for frequency vs time, but can the user also obtain the phase for each of these points?

[Liz F]

Hello,

Phase information is typically gathered by a simple frequency-domain transformation, such as an FFT. The result of an FFT is typically an array of real and imaginary numbers, which you can convert into magnitude and phase information about each of the sinusoidal waveforms that make up the signal. You could take the FFT of your data as well as perform the JTFA on it, and display both sets of information.

Please take a look at these links for more information about JTFA and its relationship to time and frequency domain measurements:

http://zone.ni.com/devzone/conceptd.nsf/webmain/0A3D35A85FC7D2EA862568D2004A966F?opendocument

http://zone.ni.com/devzone/conceptd.nsf/webmain/66A9E8BFA65260F886256C5A00792BC6?opendocument

I hope this helps!

Liz Fau
sak
National Instruments

[Chris_12345]

Liz,

No, I was asking for phase information for each wavelet. Using FFT would basically give me a time-averaged phase for each frequency.

The Signal Analysis Toolset gives the frequency of each wavelet, but does it also give the phase?

Regards,
Chris Atwood

[Xy]

Hi,
The phases associated with wavelets are not provided in SPT 7.0, but it will be available in SPT 7.1. There is a package with an example of Analytic Wavelet Transform. It provides the phase information as well as the scalogram. The attachment is available in the topic: "wavelet scale to frequency". Try to search it in this forum.

NISH DSP

[Chris_12345]

Bingo. Thank you for your help. Since I originally posted, we have purchased SPT 7.0. Looking through it, there is an example called "CWT Example.vi", that has a phase plot. Is there something that I'm not understanding? Also, why is the wavelet list different in that example?

Also, I see that "JTFA Refnum Get Data" outputs complex numbers. Is it possible to get valid phase info from that?

Is the new SPT 7.1 coming out soon?

Thanks,
Chris