Displaying Data 2
Agilent 1000B Series Oscilloscopes User’s Guide 57
10 Use the horizontal position knob to adjust the frequency per division.
The frequency scale is displayed on the screen. Use this to display the
frequencies associated with the peaks in the FFT waveform.
Figure 23 FFT Waveform
FFT Resolution
The FFT resolution is the quotient of the sampling rate and the number of FFT points (f
S
/N).
With a fixed number of FFT points (1024), the lower the sampling rate, the better the
resolution.
Nyquist Frequency and Aliasing in the Frequency Domain
The Nyquist frequency is the highest frequency that any real-time digitizing oscilloscope
can acquire without aliasing. This frequency is half of the sample rate. Frequencies above
the Nyquist frequency will be under sampled, which causes aliasing. The Nyquist
frequency is also called the folding frequency because aliased frequency components fold
back from that frequency when viewing the frequency domain.
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