Window 3 dB BW in bins Scallop loss Nearest side lobe Zero phase
reference
Coefficients
Rectangular 0.89 3.96 dB -13 dB 50% 1.0
Hamming 1.3 1.78 dB -43 dB 50% 0.543478, 0.456522
Hanning 1.44 1.42 dB -32 dB 50% 0.5, 0.5
Kaiser-Bessel 1.72 1.02 dB -69 dB 50% 0.40243, 0.49804,
0.09831, 0.00122
Blackman-Harris 1.92 0.81 dB -92 dB 50% 0.35875, 0.48829,
0.14128, 0.01168
Gaussian 2.0 0.76 dB -79 dB 50% a = 3.75 (not cosine
series)
Flattop2 3.8 0.0065 dB -90 dB 50% 0.213348, -0.206985,
0.139512, -0.043084,
0.003745
Tek Exponential 1.42 0.60 dB -67 dB 20% not applicable
3 dB BW in bins
This is the bandwidth in units of bins, which are the intervals between spectral output samples when no zero fill is used. The
bandwidth is measured between the points on the lobe that are 3 dB down from the peak of the lobe. The bandwidth in hertz may
be computed by dividing the BW in bins by the gate duration in seconds. This is also referred to as resolution bandwidth (RBW).
Coherent gain
The gain factor normally associated with different window functions is correctly scaled into the magnitude spectrum output.
Therefore, the magnitudes in the output spectrum do not change as different windows are selected.
Scallop loss
This is the magnitude error of the spectral analyzer when the frequency of the observed signal is exactly half way between two
frequency samples of the spectrum when the interpolation ratio due to zero fill of the FFT is one. When zero fill is in effect,
scallop loss is essentially eliminated because of the interpolation in the frequency domain due to zero fill. If you work with span
settings less than full and you work with larger resolution bandwidth settings, zero fill is in effect most of the time.
Oscilloscope reference
DPO70000SX, MSO/DPO70000DX, MSO/DPO70000C, DPO7000C, and MSO/DPO5000B Series 729
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