Thanks. I will first try the software route with minimal electronic compone=
nts,
if I can get it to work well and use very little CPU power, that'll be, els=
e
I'll take a look at Digikey catalog. :-)

In any case, I always learn new things in this list.

Cheers,
Mario


At 10.56 2011.12.13, you wrote:
>> 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> wro=
te:
>> >>
>> >> 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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