> Measuring when (exactly) I receive those analog pulses, just that. What
> matters to me is the time resolution.
>
> In the end it appears that the best solution for my problem may be to
> capture the rising edge, then for, say, 1 uS, check that the input pin
> remains high (no glitches).
>
> Or simply, even better, shield the thing.. perhaps with LP filtering I'm
> looking at the problem from the wrong perspective.

Deep ending how you define best.
Lookup parameters for 4 pole Bessel low pass.
Implement it using transistors as emitter followers or opam sections.
Try it.
Be amazed.

Or buy a $5 IC from Digikey and try it.


 Russell




>
> Cheers,
> Mario
>
>
> >
> >Sean
> >
> >
> >
> >On Mon, Dec 12, 2011 at 2:03 PM, Electron <electron2k4@infinito.it> wrot=
e:
> >>
> >> Hello,
> >> I have to get the *exact* timing (30ns resolution) of some low
> >frequency (<250Hz) pulses
> >> via an input capture module, however I'd like to filter the signal
> >coming in, as it will
> >> contain a lot of high frequency noise, but filtering via a capacitor
> >introduces a phase
> >> delay, which I can't even compensate (by frequency) as the phase
> >delay changes with input
> >> signal amplitude.
> >>
> >> What is the way You'd approach this problem? I thought about using a
> >zener to clip the
> >> signal and thus work on a known amplitude, but I suspect it will
> >introduce errors too.
> >>
> >> On the software side, I could make sure that the input stays high
> >for enough time, but
> >> it's pretty overkill, and I'd like to keep it as last option. If it
> >could be done [EE]
> >> then it would be better!
> >>
> >> With kind regards,
> >> Mario
> >>
> >> --
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