What does the extract single tone vi do?

[TooEagerToLearn]

When using an extract single tone vi, what does it actually do? Does it give the frequency, phase and amplitude of the HIGHEST amplitude wave? Say we provide a waveform of 400 samples of an undermined number of sine waves.....Are there any documents with block diagrams that explains this? 

[mikeporter]

Have you checked the context help? Seems to be a lot of information there.

Mike...

[TooEagerToLearn]

Seems like I wouldn't ask the question without reading "Context Help", do people do that?

I am trying to understand what it means...... Sometimes, I find NIs explanation as follows: eg. number of records: Number of records to be entered. (But, what is a record?)

My question was related to "single tone", What does that mean? Does it mean within that window, it returns the "frequency" "amplitude" and "phase" (single values for each) from a whole array of samples?

[Darin.K]

There is an amazing subVI in the Extract Single Tone information.vi, it has to be seen to be believed and then unseen as quickly as possible.

For more information there is a link in this thread:

http://forums.ni.com/t5/LabVIEW/Extract-Single-Tone-Information-from-Hann-Spectrum/td-p/139345

and for fun:

http://forums.ni.com/t5/LabVIEW/Scary-LabVIEW-images/m-p/1580676#M578210

[AdamTrojak]

It's a qoute from help "Takes a signal in, finds the single tone with the highest amplitude or searches a specified frequency range, and returns the single tone frequency, amplitude, and phase"

Do you have any questions about it?

[TooEagerToLearn]

My head started hurting when I opened and went deep into all the subvis. All I would like to know what does the output represent?

1. Just the dominant frequency?

2. Amplitude corresponding to that frequency?

3. Phase (relative to what?)

[AdamTrojak]

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@TooEagerToLearn wrote:

My head started hurting when I opened and went deep into all the subvis. All I would like to know what does the output represent?

1. Just the dominant frequency?

2. Amplitude corresponding to that frequency?

3. Phase (relative to what?)

---

1. Depends on input. If you don't specify the freq. range, than it takes tone of frequency with highest ampltude in whole signal.

2. Yep.

3. Phase is determined relative to zero (in time).

[crossrulz]

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@TooEagerToLearn wrote:

My head started hurting when I opened and went deep into all the subvis. All I would like to know what does the output represent?

1. Just the dominant frequency?

2. Amplitude corresponding to that frequency?

3. Phase (relative to what?)

1. ---

   yes, the strongest frequenc
2. Yep
3. A tone is assumed to be a sine wave.  So if the first point is the positive peak, you would get 90 degrees.

[TooEagerToLearn]

THanks guys!

If I have the drive frequency changing on loading conditions, I am sure this vi would capture the dominant frquency and amplitude. What would work to capture the harmonics? I am not sure how many, but I need to calculate power from AC current and voltage signal for both drive frequency and all other frequencies, i.e. harmonics.

[RavensFan]

Do a full-fledged FFT and look for the peaks in there.