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Unread 18-06-2014, 16:00
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Aren Siekmeier Aren Siekmeier is offline
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FRC #2175 (The Fighting Calculators)
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Re: Encoder rate noise

Quote:
Originally Posted by Joe Ross View Post
Switching to 1x decoding does not lose direction sensitivity. It still uses the B channel for direction, but only 1 transition of the A channel.

1x decoding helps reduce noise beyond just reducing counts to within the limit of the FPGA. It also allows additional digital samples between each count, effectively acting like averaging 4 samples at 4x. It also ignores manufacturing tolerances between the different signals, like Ether mentioned. For the S4 encoder, B lags A by 90 degress +/- 60 degrees (max).
Ah, thanks for that, good to know. I'm guessing 2x behaves similarly, skipping the falling edge of each channel and using it as a second sample to smooth things out relative to 4x.
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