Hello,
I am working on FFT measurements using DSA -X 91604A series oscilloscope and was analyzing the different FFT windows -Flat,Han,Ham,Rect & Blackman Harris which the scope provides.
While comparing i see that with the same setup the measured Magnitude of a spectral peak for a *blackman harris window is
8-10dBm less compared to the other windows available.*
Is it a bug? Can you please provide some insight?
Regards,
VJ
Edited by: VJ on Sep 10, 2014 11:19 AM
I am working on FFT measurements using DSA -X 91604A series oscilloscope and was analyzing the different FFT windows -Flat,Han,Ham,Rect & Blackman Harris which the scope provides.
While comparing i see that with the same setup the measured Magnitude of a spectral peak for a *blackman harris window is
8-10dBm less compared to the other windows available.*
Is it a bug? Can you please provide some insight?
Regards,
VJ
Edited by: VJ on Sep 10, 2014 11:19 AM
Spectral Analysis Using a Deep-Memory Oscilloscope Fast Fourier Transform (FFT) AN 1383-1
http://literature.cdn.keysight.com/litweb/pdf/5988-4368EN.pdf
Most measurements will require the use of a window such as the Hanning or Flattop windows. These are the appropriate windows for typical frequency analysis measurements. Choosing between these two windows involves a trade-off between frequency resolution and amplitude accuracy.
Hanning
• Advantage: Good Frequency Resolution
• Disadvantage: Less Amplitude Accuracy
Hamming
• Advantage: Good Frequency Resolution (slightly better than Hanning)
• Disadvantage: Less Amplitude Accuracy
Flattop
• Advantage: Good Amplitude Accuracy
• Disadvantage: Less Frequency Resolution
Rectangular
• Advantage: Good Frequency Resolution, Good Amplitude Accuracy (For self-windowing waveforms)
• Disadvantage: Possible Leakage Effects
Blackman-Harris
• Advantage: Good for signals with a strong interference component that is fairly distance from the frequency you want to see, good general purpose window
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