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Old Jan 28, 2004, 10:15 PM
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The blade numbers go up to 11
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Sydney, Australia
Joined Aug 2002
4,478 Posts
It was very sensitive to slight shifts in the signal phase
That's the whole idea! Basically you're working out the phase angle of the signal with respect to a fixed sine wave of the same frequency.

I've found that some motors are noisy and some aren't. It also depends on the prop - or in my case the ducted fan which is a whole lot more succeptable to accoustic ringing due to low freq pwm. In serious motor controllers the DSP's use a slightly varying pwm freq to avoid any chance of audible noise.

This is a great thread, BTW!

Stu Maxwell
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