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# DFT: Sampling and Aliasing

[Laboratory]

### Experiment: sampling and aliasing concepts

In this experiment we want to visualize the concepts of sampling and aliasing (overlap or wraparound effects). In order to do this we will generate images ranging from a minimum to a maximum frequency without any distortion. In addition, we will generate an image that violates the relationship between its maximum frequency content and the minimum sampling frequency required for distortionless representation.

Depicted below is the image of a sinusoidal signal in the width direction. Its frequency is 1/128 cycles/samples, and amplitude 1. Also displayed is its log(mag+1) spectrum. NOTE: frequency ranges from 0 (center) to +/- 1/2 (borders).

The results after increasing the frequency of the sinusoid to 16/128 cycles/samples are shown below.

We can further increase the frequency of the sinusoid to 64/128 cycles/samples. This is the maximum frequency of the sinusoid before distortions are introduced due to aliasing. The results are shown below.

If we increase the frequency of the sinusoid to 68/128 cycles/samples then the effects of aliasing can be visualized.

To improve our understanding we can extract the center horizontal line of the log(mag+1) spectrums and plot them for comparison.

- Lab: DFT: Sampling and Aliasing