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Unread 14-05-2009, 22:09
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Eugene Fang Eugene Fang is offline
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Re: Misbehaving encoders

Quote:
Originally Posted by Jared341 View Post
The theory you are describing (that you aren't reading the encoders fast enough and that they are going HIGH->LOW->HIGH so fast you don't see the "LOW" part) is known as aliasing. The Shannon-Nyquist Theorem basically states that you need to sample at least twice as fast as the highest frequency in your input in order not to miss anything. However, I don't think that's the case here, as the cRIO reads the encoder signal at many tens of KHz; you'd have to be spinning your encoder at a blazing speed to hit that.
What if you're using VEX encoders, which, according to IFI's website, can only count properly up to 1000 rpm (it might be 1000 clicks per second, i can't remember off the top of my head. either way, there seems to be a limit)
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Eugene Fang
2010 Silicon Valley Regional Dean's List Finalist

Various FLL Teams - Student (2000-2006), Mentor (2007-2010)
FRC Team 604 - Student (2007-2010), Mentor/Remote Advisor (2011-2015)
FRC Team 1323 - Mentor/Remote Advisor (2011-2014)

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