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.
Nearest side lobe
This is the difference in magnitude between the spectral lobe peak in the spectrum and the next side lobe that occurs due to
energy leakage. Different windows have different leakage characteristics. The more narrow the resolution bandwidth of the
window the more leakage in the spectrum.
Zero phase reference
This is the position in the time domain gate that is the reference point for phase in the output spectrum. That is, if a sine wave
input has its peak at the zero phase reference position, then it reads out as zero phase in the spectrum. If the phase is to be
correct when doing impulse response testing, the impulse in the time domain must be located at this position in the gate interval.
Coefficients
These are used to generate the windows that are constructed from a cosine series. For the Gaussian window, the value of "a" is
given instead of a set of coefficients. You can find descriptions of cosine series windows in the Handbook of Digital Signal
Processing Engineering Applications by Elliot. ISBN 0-12-237075-9.
What do you want to do next?
Go to a list of all spectral math controls.
Learn about using spectral analyzer windows.
Go to a step-by-step procedure for defining a spectral math waveform.
Oscilloscope reference
DPO70000SX, MSO/DPO70000DX, MSO/DPO70000C, DPO7000C, and MSO/DPO5000B Series 727
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