Encoder Dithering Specs

Hello,

I am a self-under-employed electrical engineer and was recently involved
in a discussion about quadrature encoder counting circuit requirements.
I have no particular equipment in mind. I am just exploring for now.

I have a Sherline CNC mill with stepper motors so this discussion does
not apply to me yet. But I do expect to graduate to something larger and
possibly with servos and encoders.

I understand what the counter circuit needs to do in order to count at
maximum speed in either direction. And I understand what the counter
circuit needs to do if the encoder dithers as little as one count.

How are the circuits usually specified for dithering less than one
count. Let's say the encoder A signal is oscillating and the B signal is
constant.

Pointing me toward typical specs for CNC encoders and controllers should
be adequate if they address this issue.

Tom Hubin
thubin@...