Re: [CAD_CAM_EDM_DRO] DRO ENCODER TOOL

> True Gray-code absolute encoders make sense in a rotary mode, they
> don't make any sense at all in linear encoders of moderate size and
> resolution.
> Let's figure it out. First, there is no quadrature x 4 multiplication
> of counts, so
> the number of vertical stripes of bits is equal to the resolution of the
> encoder.

Actually, that need not be true. Quadrature in effect gives you four
'states' or two bits of information off the pattern. So you can have
one pattern read in quadrature, then another at a quarter (rather than
half) that pitch, and another at a quarter of that pitch and so on
until you hit the point where the pitch is so coarse that you can't
make the read head long enough offset the detectors by 90 degrees of
phase.

In other words, an absolute encoder built with quadrature need only
use half as many tracks as bits. But it still wouldn't be practical
for most applications - an 8 or 9 track strip would be pretty wide to
be as reliable as a single track one.

Chris

--
Christopher C. Stratton, stratton@...
Instrument Maker, Horn Player & Engineer
30 Griswold Street, Cambridge, MA 02138
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