B&K Precision 2552-2559 - Manual - Manual (Page 40)

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5. The oscilloscope calculates the FFT spectrum using the
center 1024 points of the time-domain waveform.
6. Turn the “Volts/div” knob to ensure that the entire
waveform remains on the screen.
7. Turn the “Time/div” knob to provide the resolution you
want in the FFT spectrum.
8. If possible, set the oscilloscope to display many signal
cycles.
To display FFT correctly, follow these steps:
1. Push the “MATH” button.
2. Set the “Operation” option to FFT.
3. Press the “Source” button to select “CH1”, “CH2”, “CH3”, or
“CH4” according to input signal channel. (CH3 and CH4
available for 4CH models only)
4. According to Nyquist law, turn the “Time/div” knob to adjust
the sampling rate (this parameter is displayed behind the time
base parameter), making sure it is at least double the input
signal frequency.
Displaying the FFT Spectrum
Press the MATH button to display the Math Menu. Use the options to
select the Source channel, Window algorithm, and FFT Zoom factor. You
can display only one FFT spectrum at a time. You can select “Full screen”
or “Split” in “Display” option to display FFT waveform on full screen or
display channel waveform and its FFT waveform on half screen at a time.