Re: sine/cosine encoder interface schematic wanted

> I bought a(n) RSF-Electronik linear encoder/spar recently and would like to
> know what options I have the quadrature signals in lieu of buying a
> commercial readout

Just a guess, but sounds like it might be Russian made?

If you can hook it up and get sine/cosine output it would seem you
have two choices.

The simple option would be to build some sort of threshold comparator
to simply digitze the sine waves to square waves, and feed the result
to someting like Tom Kulaga and Dan Mauch's encoder card in an old
computer. The problem with this is that you loose a lot of the
potential resolution, since you only get four discrete transitions per
physical pitch unit of the encoder.

On the more complicated side, you could find a microcontroller with a
pair of fast A/D converters and build you own encoder interface chip.
Making it track the scale without losing counts while communicating
with a host computer could be tricky. I might suggest either a tiny
dual-port ram for the interface, or possible having your little micro
generate digitized quadrature signals at a higher interpolated rate
which could then be counted by one of the quadrature interface boards.
To avoid missing counts, you'll have to do an A/D conversion at least
twice in every period of the sine wave, so you need to know the pitch
of the encoder and the maximum intended feedrate to figure out what
kind of A/D converter and processor performance you need.

Chris

--
Christopher C. Stratton, stratton@...
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