10-1
IM DLM3054-01EN
10 FFT
The instrument can determine up to two input waveform power spectra (FFT1 and FFT2).* On models with the
user-defined feature (option), the instrument can determine the linear spectrum, rms power spectrum, power
spectrum, cross spectrum, transfer function, and coherence function.
FFT waveforms appear in the FFT window.
* Only FFT1 on the 2-channel model.
T
T
T
T
t
Sine wave
Time windows
Integral
Power
Spectrum
Rectangular
Hanning
Rectangular
Hanning
Flat top
: W(t) = u(t) – u(t – T) u(t):
Step function
: W(t) = 0.5 – 0.5cos(2 )
: W(t) = {0.54 – 0.46 cos(2 )}
T
T
Flat top
t
T t
T
sin{2 (1
—
2t/T)}
2 (1
—
2t/T)
Turning the FFT On or Off (Display)
Set whether or not to perform FFT analysis. If you set this to ON, the FFT window appears.
• ON: Performs FFT analysis
• OFF: Does not perform FFT analysis
Analysis Source Waveform (Trace)
You can select from one of the settings below. The available settings vary depending on the model.
CH1 to CH4, Math1 to Math4