Extract Single Tone Information.vi configuration help

Hello.
I am trying to measure speed from a sensor that outputs the speed directly to
frequency (i.e. 500 Hz = 500 RPM).
I am using the Scaled Window.vi with Hanning and the Extract Single Tone
Information.vi to get the frequency.
I successfully measured to about 500 Hz with the default settings.
My range is from 0 to 2500 Hz.
The only settings I can find that seem to let me configure sampling is the
approximate frequency and search (+/- % of Fsampl.)
These defualt to -1 and 5 respectively.
I assume this means no default frequency, or 0 and the sampling rate is 10000
(500 / 0.05).
I changed the approximate frequency to 1250 (my center frequency) and the
percent to 12.5 (10000 / 1250 ).
This resulted in labView only reading one seemingly random value or not updating
this measurement.
After putting -1 in the approximate frequency again, I was able to read values
higher than 500, but they folded around 500 (i.e. aliasing).
How do I change the settings or use another vi to get the range that I need?
Thank you,
Electro-Frog

Thank you very much mfitzsimo…,
That did the trick. It has been so long since I changed the sampling rate, that I forgot it was there.
Apparently the Extract Single Tone Information does all the calculations for you, based off the sampling rate of course.
I bumped it up to 10000 samples/sec from 1000 (where the 500 folding came from) and I could read everything my function generator could put out.
Electro-Frog

Similar Messages

Using Extract Single Tone Information to detect phase

Dear all,
I have problem using Extract Single Tone Information vi to detect phase angle of a sine wave.
I posted similar question a few days ago regarding using the same vi to determine phase angle of a square wave and realised it couldn't be done because square wave is not single tone. I modified my program slightly and use it to examine a sine wave but I still couldn't get reliable results.
Please find the attached for the program code. When I set frequency to 5 Hz, everything worked fine but when I set it to 5.17 Hz with 20 degree phase, the detected phase value keeps changing. Appreciate if you could help me on this matter. Thank you very much!
Best regards
Attachments:
SineWavePhaseAngleTest.vi ‏28 KB

Hi looloo,
Sorry for slow response! Here's the VI back-saved to LV8.2
(in case It's not too late to help...)
The "phase" output reflects the "angle" associated with the beginning value in the Y-array (when Y = amplitude, Phase is 90deg.)
Phase is changing because sine-wave (Y-input) is shifting each time single-tone is called...
Cheers!
"Inside every large program is a small program struggling to get out." (attributed to Tony Hoare)
Attachments:
SineWavePhaseAngleTest[1,LV8.21].vi ‏38 KB

Extract Single Tone Information using Flat Top Windowing

Beginner here - Does anyone have any ideas on what would be the easiest way to create a function that would essentially perform the same function as the built in "Extract Single Tone Information.vi" only that instead of using Hanning windowing (as I noticed that this Vi does) I would be able to use Flat Top (or selectable windowing)? I basicly need to set something up that will accept an incoming Sine wave and apply FFT using Flat Top windowing then output the measured frequency and the amplitude of that frequency. I need to still be able to input the "advanced search" criteria into the VI and give it a frequency and tolerence to look for as I don't want to just look for the peak signal but at specific frequencies.

I am running Labview 7.1.1 (that's what my company uses and they refuse to upgrade). I can't open files built under anything newer than LV7.1.1.
I really don't want to just do a peak search of the entire spectrum and would rather enter a specific frequency to look for and the tolerance window (find peak at say +/- 2% tolerance away from known recorded frequency. This test is targeted as a production test we will be shipping to several parteners around the world to use in production. This will be a test fixture to perform testing on electret boom microphones. The fact that it will be used in a production environment there is potential for high levels of background noise (radios, floresent lights, people talking, etc) and therefore I need as much filtering as possible to only the frequency i am trying to measure. I will be outputting a specific frequency from a speaker and recording it back through the microphone under test via a NI USB-6211 DAQ.
Can anyone tell me if "Extract Single Tone Information fron Hann Spectrum.vi" has anything in it which would limit me to only inputting a Hann windowed FFT into the signal input of that VI? This is the VI which is password protected in my 7.1.1. copy of Labview. If it doesn't and I could feed it a Flat Top windowed FFT signal into it without problem I am golden. I can modify the other sub-vi ("FFT with Hanning") and the main "Extract Single Tone Information 1CH.vi".
Thanks for you continued input.
P.S. I am fairly new to Labview (<2yrs)

Référence de phase de la fonction "Extract single tone information"

Bonjour !
J'utilise actuellement la fonction "Extract single tone information" pour calculer la phase d'un signal acquis avec un DAQ 6211. J'aimerai donc savoir quelle est la référence pour calculer la phase du signal ? J'ai ouvert la fonction et les sous VI qui la compose mais je vous avoue que la compréhension de cette fonction dépasse mes compétences (je suis étudiant à la fac en L3).
J'utilise notamment cette fonction pour réaliser un phasemètre donc j'ai récupéré la phase de 2 signaux déphasé (par l'intermédiaire d'un DAQ 6211) avec cette fonction et j'ai soustrait "phase2-phase1" pour avoir le déphasage, mais le résultats rendu est tantôt une valeur "phi", tantôt "phi-360".
Merci par avance de vos réponses !

Bonjour,
Pour vous aider à utiliser le VI "Extract Single Tone Information", vous pouvez consulter les exemples qui permettent d'illustrer le fonctionnement du bloc dans son contexte.
La localisation de ces exemples se situe dans l'aide (tout en bas). Voici le lien direct : Extract Single Tone Information VI
Cordialement,
Jérémy C.
National Instruments France
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Travaux Pratiques d'initiation à LabVIEW et à la mesure
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Extract Single Tone Information - phase step

Hello!
I am using Extract Single Tone Information to measure amplitude, frequency and phase of a slowly varying signal.
But sometimes the phase jumps ~350 degrees for no apparent reason. I have made a small vi (in LabView 8.5 professional) to demonstrate this, see attachment.
Seems like the shift occurs when the ends of the input signal cross each others level, in opposite directions.
Guess I should start looking for an alternative method for doing the measurements.
Any suggestions or ideas are most welcome.
Attachments:
phase_test.vi ‏30 KB

Hi Thomas
It jumps 360 degrees to be exact. -180 degrees and +180 degrees is basically the same thing so the phase you are seeing is correct. It does not look very good in a chart though. To improve the looks you can use the subVI called "Unwrap phase".
Regards
Øyvind Ø

Extract Single Tone Information from Hann Spectrum

I need to examine the details of "Extract Single Tone Information from Hann Spectrum.vi" but i couldn't because it is password protected. How can i remove this password?Is it NIs strategy to set the password to some vi's?.Or is there any other function behaving like "Extract Single Tone Information from Hann Spectrum.vi" so that i can see inside?
Regards.

I have attached a Power-Point presentation from NI-Week 1999 that describes the algorithm concept and performances. Note that the function shipping with LabVIEW is more complex (and more accurate) than the one described, but I hope this will give you a good idea on how things are implemented.
Attachments:
tm3bb.ppt ‏1174 KB

Does the Extract Single Tone Information.vi only find the fundamental harmonic?

I capture a waveform that only has 1 frequency. If I use the Extract Single Tone Information.vi to extract a single tone, is this single tone the fundamental harmonic? And if I feed the residual portion of the waveform into the Extract Single Tone Information.vi, will the next tone be the second harmonic? And so on? Is it possible to compute the total harmonic distortion just by feeding the the waveform into the Extract Single Tone Information.vi over and over again (only feed the residual waveform into the vi continously)?
Message Edited by solitude on 08-18-2005 09:28 AM

Notice the title of the vi: Extract SINGLE Tone. It is expecting only one frequency. This vi is not intended to handle a carrier frequency or audio with harmonics. You say that you capture a waveform that has 1 frequency. If this is so, then there should be no harmonics. To measure harmonic frequencies, you must perform spectral analysis. To measure total harmonic distortion, there exists a THD vi in the Waveform Analysis palette.
- tbob
Inventor of the WORM Global

How to connect meter to o/p of extract single tone information

plz tell me how to do this....
thanks in advance

Just wire it. Your (poor) question speaks volumes about your lack of experience. Have you taken the basic tutorial?

Extract Signal Tone Information in Control & Simulation Loop

Hi,
I have a simple Block Diagram to try Control & Simulation Loop. I added a Sine Wave signal and a Waveform Chart connected to it. They work just fine.
I tried to add a Extract Single Tone Information , from Signal Processing, and connect it to the output of the Sine Wave generator but I do not know how to create a proper Time Signal.
I thought of storing the output of the Sine Wave in an array but I was unsuccessful since I could not add any shift register to this type of control loops.
Any help or suggestions?
Thanks
Attachments:
Control_n_Sim_Test.PNG ‏9 KB

Hi Siamak,
Thanks for your reply mate.
However, when I built a same BD as you posted on, it somehow didn't work. I also attached a photo of my BD here. I used the gauge to measure when I run the programme. The gauge shows there is no signal output after the "collector"VI (gauge no.13). would you please check it for me? Many thanks!
BR
Floyd
Attachments:
tone info extraction.png ‏134 KB

Measuring frequency or amplitude using extract single tone information

Hi All,
I'm trying to read speed of a drill and was hoping that I could use the information extracted from Extract Single Tone Information to get to the speed. However, when I run the attached code while the drill is still off I get Inf for frequency and 0 for amplitude (the waveform chart shows numbers in the 0.21 range - see attached picture). When I turn on the drill the signal amplitude as viewed on the waveform chart jumps to ~4 range, but the frequency continues to read Inf and the amplitude 0. Am I missing something, or using the Extract Single Tone Information incorrectly?
Thanks!
Attachments:
Drill Encoder Test.vi ‏21 KB
Drill Turned Off.JPG ‏38 KB
Drill Turned On.JPG ‏40 KB

Hi,
Thanks so much for your quick response.
As to point 1, I actually see data come in, over time. I could only capture a snapshot of it, hence the photo, but if I continue the run data continues to come in over time. I believe I've fixed the array vs waveform issue (see my modified code). I ended up with that because I was trying (out of desperation) different Analog Wave form function. I'm seeing lots of data, but no actual numberical values for frequency of amplitude.
Thanks again!
Attachments:
Drill Turned Off 2.JPG ‏42 KB
Drill Turned On 2.JPG ‏40 KB
Drill Encoder Test.vi ‏21 KB

Extract Single Tone.vi

does,anyone knows how to get the diagram of the VI :Extract Single Tone
Information.vi given un lv6i it is password protected.

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?)
yes, the strongest frequenc
Yep
A tone is assumed to be a sine wave. So if the first point is the positive peak, you would get 90 degrees.
There are only two ways to tell somebody thanks: Kudos and Marked Solutions
Unofficial Forum Rules and Guidelines

Why is the amplitude smaller when using the Extract Single Tone VI to measure the amplitude of a signal?

Whenever I measure the amplitude of a signal using the Extract Single Tone VI, the amplitude is smaller than if I measured the signal by hand by positioning the top and bottom cursors to the highest and lowest peaks of the captured waveform. Should I not use the Extract Single Tone VI to measure amplitude? I'm using Labview 6i.

I'm not exactly sure but I think the amplitude from the Extract Single Tone vi is in peak volts (Vp). When you use the cursors on a scope set to the top and bottom peaks, you are measuring volts peak to peak (Vp-p). If the Extract vi amplitude is one half of your scope reading, then this is true. Just double your Extract vi amplitude to get the peak to peak voltage. It also depends on the signal. If your signal is a square wave from 0 to 5 volts (TTL), this is usually measured in peak voltage. A sinewave going positive and negative (from -5 to +5) is usually measured in peak to peak.
- tbob
Inventor of the WORM Global

What does the extract single tone vi do?

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?

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?)
yes, the strongest frequenc
Yep
A tone is assumed to be a sine wave. So if the first point is the positive peak, you would get 90 degrees.
There are only two ways to tell somebody thanks: Kudos and Marked Solutions
Unofficial Forum Rules and Guidelines

"Extract Single Tone" functionality in Measurement Studio or alternative source?

Hi everyone. We have used the LabVIEW Extract Single Tone vi successfully for prototyping and now want to build similar functionality in a product being written in Measurement Studio. This function calcluates the amplitude, frequency and phase for a time varying signal. Does anyone know if similar functionality exists in Measurement Studio? Alternately, does anyone know of a C++ library that is available elsewhere with this functionality?
Thanks!
Craig

I took a quick look inside this VI. It uses non DLLs just standard labview functions. So in worst case you can reverse engenier it.
Besides which, my opinion is that Express VIs Carthage must be destroyed deleted
(Sorry no Labview "brag list" so far)

Extract single tone function

I am looking for an extract single tone function. In labview there is such a function. I expect there is a simular function available in measurement studio. I can however not find this function.
Any example how to calculate base frequency from measurement data.
Thanks, Jan

I post this message on wrong forum
Because i using vc#.net
Jan

Extract Single Tone Information.vi configuration help

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