Time Record LengthAnalyzer Set-Up for Synchronous Averaging
Here, the FFT analyzer is used not as a frequency analyzer, but as a time-domain averager. Many, but not all, FFT analyzers have this capability. We will see that the setup parameters for synchronous averaging are generally quite different from those needed for spectrum analysis.
There are two important considerations in setting up a synchronous averaging test, the Time Record Length, and the Time Domain Resolution. The length of the time record is usually set up to be at least a little longer than one revolution of the of the shaft you are looking at, or one cycle of the event you are studying. There is usually no reason to use a longer time record, since you simply lose resolution in the time domain. The fixed number of samples is spread over a longer time; so short events during the motion you are analyzing could be lost.
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