Time Synchronous Averaging
Note: This feature is not available on the vb5 or vb6 instrument models.
Time synchronous averaging is a useful vibration analysis technique for distinguishing between spectral peaks that are very close to, but not exact harmonics of, the machine's running speed. After performing a large number of averages, peaks that are whole number multiples of the running speed will still be visible, while those that are non-synchronous will be cancelled out from the spectrum.
The key parameters you need to set are the duration, number of samples and number of averages.
The duration determines the equivalent Fmax value. If the waveform is later transferred to Ascent and displayed as a spectrum this Fmax value will be used on the chart. The number of samples controls the number of spectral lines used when the waveform is transferred to Ascent and displayed as a spectrum.
We recommend you use 16 or more averages in order to remove non-synchronous peaks from the final spectrum.
Note: You must use a tachometer or Keyphasor® to trigger your measurements.
- Connect the tachometer or Keyphasor® that will be used to trigger your measurements.
- From the Main Menu press
Measure then 
Time Synch Avg. - Use the left-hand arrow keys to select a parameter set or press
to create a new one and set the parameters as required. - If you are creating a new parameter set, select the number of samples, duration and tach trigger source, then press
and 
to set the number of averages. - Press
to begin measuring.
Last Reviewed: 11/Jun/2009 Source: vbSeries Reference Guide Revision 24 Mar 2009 - pages 71 & 72