RussellMc wrote:
> Simplistic example. If random noise is added to a signal and it reads
> 145 mV 60% of the time and 146 mV 40 % of the time then actual voltage
> MAY be about 145.4 (not 145.6) mV. Take care when arttempting to apply
> this magic. It does work, but ...

It's pretty easy to apply on the firmware end.  Just low pass filter
multiple A/D readings.

When you have the cycles and real time available, it's a good idea to
oversample with the A/D, then low pass filter in firmware anyway.  It gets
you a little extra resolution if the right kind of input noise is present a=
s
you said, but it also reduces quantization noise and relaxes anti-aliasing
filtering requirements on the external hardware.

Fortunately a single pole low pass filter is easy to compute:

  FILT <-- FILT + FF(NEW - FILT)

where FILT is the low pass filter being updated with input value NEW each
iteration.  FF is the "filter fraction".  FF =3D 1 is just a pass thru filt=
er,
and FF =3D 0 is a infinitely heavy filter.  Useful values are obviously in
between.  In a small system with limited math capabilities, you often
arrange FF =3D 1/(2**N), so that the multiply by FF becomes a right shift b=
y
N.


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