How to measure frequency values on the X axis and its amplitude on Y axis

[MayureshDhakad]

Hello friends,

 I want to save  the frequency and its amplitude values on Xand Y axis respectively in tabular form. I have to save it completely from start to stop it manually.

Its the continuous sample data.

Please suggest me what changes I have to do for it.

I have done the VI upto FFT but unable to save these data.

[Bob_Schor]

Well, you click here on this Control and ... oops, I just realized I can't see your code and thus can't see what you've done, can't suggest where you should change things, can't make suggestions to help you understand how to do this properly.

Read the Forum Guidelines.  Post your code.  Do not attach a picture of a Block Diagram, but rather attach the VI (or, if you are using LabVIEW Project and have multiple VIs, compress the folder containing the VIs and attach the resulting .zip file) so we can see what you are doing.  [This will also tell us which version of LabVIEW you are using and other information that will better allow us to provide useful advice].

Bob Schor

[MayureshDhakad]

I have attched the VI.

Please go through it and suggest me the solution.

I have added there "WRITE TO MEASUREMENTS" but its giving me only amplitude on Y-axis and not giving the respective frequency reading on X-axis.

Please check the another file which I have saved while testing.

[Bob_Schor]

Sigh.  The only thing I like less than Express VIs are Dynamic Wires, and for similar reasons -- both have a tendency to over-simplify what is going on, hiding too many details, especially from beginners.

Here's a suggestion -- write a simple VI that takes a single channel and performs a Spectral Measurement (why are you doing PSD?  Why not start with something simpler, like Magnitude or Phase?).  Instead of trying to work with data from a triaxial accelerometer, start with a known signal, say a sinusoid whose frequency you know.

Ooh, there's even an example you could look inspect -- look for "Express VI - Spectral Measurements" in the Examples, under "Analysis, Signal Processing, and Mathematics", sub-section "FFT and Frequency Analysis".  If you want the frequency to have a log scale, that's a Plot Property you can change.

Bob Schor