B&K Precision 2532B - Manual - Manual (Page 47)

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4. Turn the horizontal “POSITION” knob to position the part
of the YT waveform that you want to analyze in the center
eight divisions of the screen.
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” or “CH2”
according to input signal channel.
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.