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Originally Posted by KenWittlief
only thing I disagree with on your post is the sensor has a bandwith of 40Hz or so, but your bot is heavy enough that IT wont have a bandwith anywheres near the 26mS sample loop
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Sampling at 38Hz will only allow you to resolve frequencies as high as 19Hz. Anything above 19Hz will be reflected back below 19Hz through a process called
aliasing. 19Hz is called the Nyquist frequency (I know you know this Ken; I just thought others might find this interesting). Here is an excerpt that I ganked from the web that gives an overview:
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Nyquist's Signal Sampling Theory
In the late 1920s, the only technology to preserve musical recordings was to copy sound waves in wax. Harry Nyquist, an AT&T scientist, thought there was a better way. He wrote a landmark paper (Nyquist, Harry, "Certain topics in Telegraph Transmission Theory," published in 1928) describing the criteria for what we know today as sampled data systems. Nyquist taught us that for periodic functions, if you sampled at a rate that was at least twice as fast as the signal of interest, then no information (data) would be lost upon reconstruction. And since Fourier had already shown that all alternating signals are made up of nothing more than a sum of harmonically related sine and cosine waves, then audio signals are periodic functions and can be sampled without lost of information following Nyquist's instructions. This became known as the Nyquist frequency, which is the highest frequency that may be accurately sampled, and is one-half of the sampling frequency
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The full text can be found
here.
-Kevin