[time-nuts] looking for algorithms to locate edge location in noisy data

[Chris Albertson]

On Mon, Mar 14, 2011 at 12:26 PM, beale <beale at bealecorner.com> wrote:
  I imagine I would want to generate a prototype waveform and then
slide it back and forth over each given waveform in turn, and look for
the best match position (cross correlation) ?

I think that is called an "autocorrelation."
http://en.wikipedia.org/wiki/Autocorrelation
There is a quick way to calculate this using FFT.

But in this special case could your "prototype" be a perfect unit
height square wave.  Then I think the time domain calculation is
simpler, I think.

But this s a real special case. so I think what I'd do is fit a line
to the linear part of the slope (say from 20% to 80% of logic high)
using least squares then solve for the mid point voltage.   Any method
like that that uses a large number of samples should reduce noise


-- 
=====
Chris Albertson
Redondo Beach, California