CLIOwin 6.5 PCI User's Manual - Audiomatica Srl

9 FFT AND RTA
9.1 INTRODUCTION
By selecting the FFT command from the main menu bar, it is possible to carry out Fourier
analysis of the input signal to determine its frequency content using the Fast Fourier
Transform (FFT).
The processed data can be displayed as narrowbands or 1/3 (or 1/6) octave bands,
turning the instrument into what is generally called a real-time analyzer (RTA).
The ability to process two channels simultaneously, to select the appropriate sampling
frequency and the possibility of triggering with respect to the generated signal make
this control panel a flexible and valuable instrument. Finally, there is also a very useful
facility to quickly and easily swap back and forth between the time and frequency
domains.
9.2 FFT CONTROL PANEL
Fig. 9.1 The FFT control panel
Fig. 9.1 shows the FFT and RTA control panel. Follow a description of the FFT control
panel toolbar and settings.
RTA operation is obtained simply by selecting the appropriate frequency axis property
(either 1/3 or 1/6 of octave) within the FFT settings dialog (see 9.3). When operating
as RTA the FFT window's title is changed (as in Fig.9.1) in 'FFT 1/3 OCTAVE' or 'FFT 1/
6 OCTAVE'.
For a detailed description of the graphical display (common also to other measurement
control panels) and its capabilities please refer to Chapter 7. For a description of the
available shortcuts please refer to section 5.5.2.
Chapter 9 - FFT 77