Discrete Fourier Transform from Noisy Sample

Author:: David Weppler

Topic:: Complex Numbers, Integral Calculus

Drag points A, B, C in the Frequency Domain to set the amplitude and frequency of the signal components. Use the sliders to see how the Discrete Fourier Transform (DFT) is affected by the number of samples, sampling interval, and level of background noise. Use the

slider to re-draw the output if it appears incorrect.

What happens to the Nyquist Frequency when you increase the Sampling Interval?

Select all that apply

A
Nyquist Frequency increases
B
Nyquist Frequency decreases

Check my answer (3)

Aliasing is when the signal contains components higher than the Nyquist frequency. Slowly increase the frequency of component C (drag the point to the right) to the Nyquist frequency then beyond. What happens to the peak associated with this component?

Select all that apply

A
The peak disappears
B
The peak is reflected across the Nyquist frequency to form the alias
C
The peak begins again at and increases from there

Check my answer (3)

Introduce some random noise using the slider. What happens to the DFT output?

Select all that apply

A
The location () of the peaks changes
B
The height of the peaks stays the same or slightly increases
C
The output flattens out

Check my answer (3)

Discrete Fourier Transform from Noisy Sample

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