FFT Spectral Analysis 4
Keysight InfiniiVision 3000T X-Series Oscilloscopes User's Guide 97
 
FFT Spectral Leakage
The FFT operation assumes that the time record repeats. Unless there is an 
integral number of cycles of the sampled waveform in the record, a discontinuity is 
created at the end of the record. This is referred to as leakage. In order to minimize 
spectral leakage, windows that approach zero smoothly at the beginning and end 
of the signal are employed as filters to the FFT. The FFT Menu provides these 
windows: Hanning, Flat Top, Rectangular, Blackman-Harris, and Bartlett. For 
more information on leakage, see Keysight Application Note 243, The 
Fundamentals of Signal Analysis at 
http://literature.cdn.keysight.com/litweb/pdf/5952-8898E.pdf.