I guess these defects may be available although much smaller even on a "perfect" encoder. TTL circuits quite usually have quite different rise and fall time but I even though i did not measure I guess it may be the same for CMOS circuits. I also expect less than perfect phase shift but I may be wrong, it all depends on if it is equally hard to get distance between pulses on same quadrature equally spaced as these phase.
I do speed estimation by measuring time between positive flank on one quadrature input which is similar but do not use all four flanks. I would guess measuring 4 sample moving average which is equal to time between four flanks will be the best algorithm unless change of speed during this period is larger than noise. I say his algorithm is very good. Nicklas Karlsson On Sun, 02 Aug 2015 19:21:09 -0400 John Kasunich <jmkasun...@fastmail.fm> wrote: > Andy: > > He has a homemade encoder with less than perfect 50/50 > duty cycle and less than perfect 90deg phase shift. So he > gets velocity jitter. He's trying to make a 4 sample moving > average, since the jitter should cancel out over a full quadrature > cycle. > > In theory that will be faster responding than a lowpass filter. > Since the velocity feedback is used in a spindle speed loop, > adding delay (the lowpass) makes tuning harder. > > Gene: > > If you XOR the two quadrature signals together you'll get one > edge (rising or falling) on every transition. > > The HAL oneshot component can be configured to produce > a pulse on both rising and falling edges. > > > > On Sun, Aug 2, 2015, at 05:42 PM, andy pugh wrote: > > On 2 August 2015 at 16:32, Gene Heskett <ghesk...@wdtv.com> wrote: > > > I need a net signal to strobe the 4 sample_hold .hold's, how can that be > > > obtained? > > > > I think we would need more information about what it is you are trying > > to do, and how you are trying to do it. > > What are you trying to do that normal denounce and lowpass won't do? > > > > -- > > atp > > If you can't fix it, you don't own it. > > http://www.ifixit.com/Manifesto > > > > ------------------------------------------------------------------------------ > > _______________________________________________ > > Emc-users mailing list > > Emc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > -- > John Kasunich > jmkasun...@fastmail.fm > > ------------------------------------------------------------------------------ > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
