Zoom-FFT
SAMURAI™-Option
High-resolution FFT analysis around a center frequency
Overview
Application
High frequency resolutions sometimes cannot be achieved with a conventional FFT analysis, since this would require too many lines in relation to the necessary bandwidth. The Zoom-FFT option provides an algorithm that can be used for narrowband analyzes with such a required high frequency resolution, e.g., for signals with frequency components that are close to each. The desired frequency resolution is achieved with a Zoom-FFT at the expense of the fact that the analysis only takes place in a restricted frequency range within the original bandwidth.
Description
This option enables FFT analysis with high resolution in a restricted frequency range.
The user first choses the center frequency of interest for the Zoom-FFT and also the width of the frequency range, either directly or via the so-called zoom factor (channel bandwidth / examination width). The desired frequency resolution is achieved by choosing a sufficient number of bins in the examination area.
Figure 1:
Vibration analysis of an engine run-up. Zoom-FFT spectrum and FFT spectrum is shown.
Figure 2:
Sonogram display of the FFT spectrum over the entire frequency range.
High levels at low frequencies around 100 Hz and high frequencies around 1500 Hz are shown.
Figure 3:
Sonogram display of the Zoom-FFT spectrum with high frequency resolution at a center frequency of 100 Hz.
Figure 4:
Sonogram display of the Zoom-FFT spectrum with high frequency resolution at a center frequency of 1500 Hz.
Features
| Signals | Typically used with microphones or sensors for structure-borne signals |
| Scope |
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Requirements
This software option requires a valid SAMURAI™ base license.