Hi,
for analysis of rotating systems, order analysis would probably
be a good choise. See the following link for more information:
http://zone.ni.com/devzone/cda/tut/p/id/3779
The LabVIEW Sound and Vibration Measurement Suite or Toolkit offers a
lot of functions to perform different analysis of your signal:
http://www.ni.com/soundandvibration/software.htm
Please provide some more information about your measurements, to figure
out a function that fits to your problem. If you just want to extract
an area from your measurement signal, the standard functions for signal
processing or the array functions in LabVIEW should be sufficient.
regards,
Nikolai