110 Keysight InfiniiVision 3000T X-Series Oscilloscopes User's Guide
5 Math Waveforms
• Window— selects a window to apply to your FFT input signal:
• Hanning — window for making accurate frequency measurements or for
resolving two frequencies that are close together.
• Flat Top — window for making accurate amplitude measurements of
frequency peaks.
• Rectangular — good frequency resolution and amplitude accuracy, but use
only where there will be no leakage effects. Use on self-windowing
waveforms such as pseudo-random noise, impulses, sine bursts, and
decaying sinusoids.
• Blackman Harris — window reduces time resolution compared to a
rectangular window, but improves the capacity to detect smaller impulses
due to lower secondary lobes.
• Bartlett — (triangular, with end points at zero) window is similar to the
Hanning window in that it is good for making accurate frequency
measurements, but its higher and wider secondary lobes make it not quite
as good for resolving frequencies that are close together.
• Vertical Units — For FFT (Magnitude), you can select Logarithmic (decibels) or
Linear (V RMS). For FFT (Phase), you can select Degrees or Radians.
Use the multiplexed knobs for the [Math] key to adjust the FFT waveform
vertical scale and offset.
• FFT Gating— When the zoomed time base is displayed, press this softkey to
select:
• No Gating — the FFT is performed on the source waveform in the upper
Main time base window.
• Gate By Zoom — the FFT is performed on the source waveform in the lower
Zoom window.
• Detection Type— When the FFT (Magnitude) operator is selected, this softkey
lets you set the FFT detector decimation type.
Detectors give you a way of manipulating the acquired data to emphasize
different features of the data. Detectors reduce (decimate) the number of
FFT points to at most the number of specified detector points. In this
reduction, sampled FFT points are bucketized, that is, split into a number of
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