Paul Dietz Wrote:

>      There is a much better way! It is called a median filter.
>      Basically, this is just like a moving average (or more
>      generically, an FIR) filter, except that you take the median of
>      the data instead of the average. You do this by sorting the
>      data in the window by value, and then outputing the value which
>      ends up in the middle.
>

Alas!  I have spent a couple days messing around with median filters.
 The first one I wrote pushed large values off the end of the sort
stack, into lala land.  It would never climb up.  The next one pushed
them off the bottom of the sort stack.  Would never climb down.
Finally I got one that read in 32 analog values, sorted them, and
took the median as the setpoint.  Code works. BUT the  Relay fires
whenever I hit the lamp on my bench.  Noise immunity is still out of
reach after a lot of hard work.  Oh well, I know how to sort now.   I
fear the noise immunity is harder to buy than this.

I see three avenues:

1. Go postal.

2. Try a longer time delay between measurements, until I get around
the noise.

3. give up on median filters as being too complex, and going back to
averaging.

Another day, another $0.50 US.

Best Regards,

Lawrence Lile