aliasing

aliasing - Hello everyone, It appears there is a lot of...

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Hello everyone, It appears there is a lot of confusion regarding aliasing and the second problem from homework set 5. Some confusion might have been caused by me, but hopefully we can clear everything up! First of all, for this class we are considering a frequency to be aliased if it appears as a lower frequency. If a higher frequency appears as a lower frequency we are not considering the lower frequency to be aliased. I provided an example in hopes that it might provide some intuition. Lets pretend that your eye can capture images at the rate of 5 pictures per second. You are a passenger in a car on the freeway and you are looking at the wheels of the car next to you. Lets also pretend that the wheel has an arrow from the center to the edge and the wheel is rotating in what appears to be a counterclockwise direction. The arrow on the wheel points in the positive x -axis when t = 0. In this case aliasing would occur when the apparent speed (the speed and direction you see the wheel turning) is not the same as the actual speed. The Nyquist sampling rate is twice the highest frequency. Since our sampling rate is 5, any speed over 2.5 revolutions per second would be aliased. Now lets look at 6 consecutive images your eye can capture starting at t = 0 with different speeds . 1 revolution per second:
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This document was uploaded on 01/20/2012.

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aliasing - Hello everyone, It appears there is a lot of...

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