Sampling

August 16, 2006 at 11:43 pm | | cool results

I’m just finishing up a class on Fourier transforms, and the discreet transform has me all gooey about sampling. Have you ever noticed that computer screens shown on TV sometimes have a line moving though the picture? It’s a sampling error. The frame rate of the TV camera is similar to the refresh rate of the computer screen. As a result, the refreshing sweep is visible. It’s like strobing a light with exactly the same frequency as a spinning fan. The result to your eye is a stationary fan. Check out the link in Figure 1.

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Figure 1. Remember, this movie is shot and shown in real time.

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  1. If you love Fourier series, check out: http://www.falstad.com/fourier/
    .
    Be sure to use the “Sound” function to hear what you’re making. And you can draw your own funtion!

    Comment by sam — August 19, 2006 #

  2. Lets give proper credit where its DIY (hahaha). I saw this little DIY project a little while ago and toyed with making a larger version for a burning man installation.

    Really simple, and I’ve been itchin’ to learn how to program microprocessors for some time now. The only question is where can I get a cheap set of large UV strobe-lamps???

    Comment by ilya — August 23, 2006 #

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