Math FFT
120 TDS1000/2000-Series Digital Oscilloscope User Manual
Selecting an FFT Window
Windows reduce spectral leakage in the FFT spectrum. The FFT
assumes that the YT waveform re peats forever. With an integral
number of cycles (1,2, 3, ...), the YT waveform starts and endsat the
same amplitude and there areno discontinuities in the signal shape.
A non-integral number of cycl es in the YT waveform causes the
signal start and end points to be at different amplitudes. The
transitions betweenthe start and end points cause discontinuitiesin
the signal that introduce high-frequency transie nts.
Time-domain
(YT) waveform
Without windowing
FFT
Discontinuities
Center 2048
data points