04-04-2013 05:21 PM - edited 04-04-2013 05:22 PM
Hello to everyone,
first of all I'm a beginner of the signal's analysis and I hope someone can help me.
I'm trying to perform the time-frequency analysis of some vibration signals, acquired on a internal combustion engine. In particular I must do the tfa of a vibrational signal corresponding to one thermodynamic cycle of the engine; my Lb version is 2012.
In order to do this I'm using the advanced signal processing toolkit, in particular the "tfa stft spectogram" and I have attached in this message the simple VI I created. My issue is that in the intensity chart I should see frequencies about kHz, instead in my VI i see at max 25Hz.
Can someone help me in telling me in what I'm wrong?
04-05-2013 07:23 AM
Have you provided the correct sample rate to the spectrogram vi?
Load some meaningful data and then rigth click on the XY Graph -> Data operations-> Make current values default
Save the vi and post it again. Or post a datafile too 😉
04-05-2013 10:56 AM
Hi Henrik,
thanks for the answer and the help.
Yes I did, if you mean the sample rate on the little block "tfa stft spectogram". However I followed your suggest but nothing's changed.
I attached one example of the vibrational signal of one thermodynamic cycle as you requested. Have you any other ideas?
04-08-2013 02:38 AM
Almost 😉
Just play with the parameter (and read some basics to understand what you are doing)
04-08-2013 02:44 AM
and the vi
04-08-2013 12:29 PM
Yes, that's perfect!
Thanks very much Henrik, you've created a great event driven VI!
Actually I'm going to start read the "time frequency analysis tools- user manual" by NI; do you think is it a good guide?
.
07-16-2013 10:11 AM
Hello to everyone,
is there anyone that could tell me why when i try to plot the TFA 2D rappresentation (time vs frequency) in a 3D surface the values on the three axis do not match with those of the spectrogram?