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Using Features for Advanced Applications
TDS 500C, TDS 600B, & TDS 700C User Manual
3–195
8. Press Set FFT Window to (side) repeatedly to choose from the following
window types:
Rectangular — Best type of window for resolving frequencies that are very
close to the same value but worst for accurately measuring the amplitude of
those frequencies. Best type for measuring the frequency spectrum of
nonrepetitive signals and measuring frequency components near DC.
Hamming — Very good window for resolving frequencies that are very
close to the same value with somewhat improved amplitude accuracy over
the rectangular window.
Hanning — Very good window for measuring amplitude accuracy but
degraded for resolving frequencies.
Blackman-Harris — Best window for measuring the amplitude of
frequencies but worst at resolving frequencies.
The topic Selecting a Window, on page 3–207, provides in depth information
on choosing the right window for your application.
9. If you did not select Phase (deg) or Phase (rad) in step 7, skip to step 12.
Phase suppression is only used to reduce noise in phase FFTs.
10. If you need to reduce the effect of noise in your phase FFT, press Suppress
phase at amplitudes < (side).
11. Use the general purpose knob to adjust the phase suppression level. FFT
magnitudes below this level will have their phase set to zero.
The topic Adjust Phase Suppression, on page 3–205, provides additional
information on phase suppression.
12. Press OK Create Math Wfm (side) to display the FFT of the waveform you
input in step 1. (See Figure 3–94.)