What is the "magnitude" in the "Extract Single Tone Information VI" ? thanks

[User_1979]

Hi everyone,

I am measuring a AI at sampling rate of 500 Hz and taking 1000 samples. I am using the Extract Single Tone Information VI to get the frequency, the magnitude and the phase of the signal. The Frequency works fine, but I don't know what the "magnitude" output of the VI sends out. It doesn't seem to be the average value of the voltage over 1, 2 or 3 full periods (I have checked with the log file I have attached here). It is not measuring the average out of all the samples (since it is not the same value as the Mean.VI.) And it is neither not (Max+Min)/2

The default values of the indicators are the results are linked to the values in the log file  

Could anyone tell me what the magnitude value is from that .VI ?

Thanks a lot,

User

[JDlabview]

Hi,

First, I don't see any "magnitude" in your VI, but an "amplitude".

Secondly, of course your frequency is correct as it is constant.

Finally, read the help of Extract single tone information VI : it gives you the frequency, amplitude and phase of the single tone with highest amplitude.

Hope this helps

Message Edité par JDlabview le 06-17-2010 11:25 AM

[User_1979]

Thanks for answering.

I now understand that it consideres the period with the highest amplitude, but  I still don't understand what kind of  amplitude is given by the VI...

Any help would be great.

User