Tektronix TBS2000 Demo Manual page 16

8. Using an FFT to Analyze a
Signal's Frequency Spectrum
The FFT function calculates the frequency input of the
source waveform. Cursors make it easy to measure
frequency and amplitude in the spectrum.
1. Keep the TPP0100 passive probe connected to
Channel 1 and the Probe Comp output.
2. Press Default Setup. Press Autoset.
3. Press the F button for FFT function on the front panel
(Figure 14).
4. By default, the source waveform is on. Turn it off by
pressing the Source wfm bezel button.
5. Source Channel, Vertical Units, Window Type ,
Horizontal Center Position and Scale may be adjusted
by selecting the corresponding bezel button and
adjusting with the MPK .
6. The FFT readout panel in the top right corner of the
waveform display shows important settings.
7. The default FFT window is Hanning. Use the Window
bezel button and MPK to switch to the Rectangular
window and note the result.
8. Press the Horizontal Scale bezel button and use the
MPK to adjust the horizontal scale to 1.56 kHz/div,
9. Press the Cursor button and position the cursors on
the third and fifth harmonic frequencies (Figure 15).
10. The delta between third harmonic and fifth harmonic
frequency should be 2 kHz, which is consistent with
the 1 kHz fundamental frequency of the Probe Comp
output.
28 JULY 2016
Figure 14. The FFT Menu
Figure 15. Cursors positioned on the 3 kHz and 5 kHz
harmonics of the 1 kHz probe comp output .
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