[time-nuts] Using cheap sound cards for measurements

Bruce Griffiths bruce.griffiths at xtra.co.nz
Fri Aug 21 21:20:18 UTC 2009


That particular method is vulnerable to RF pickup from within the PC.
The coax screen should be RF grounded at both ends.

Bruce

Christian Vogel wrote:
> Hi Lux,
>> Syncing inexpensive cards is a real chore (and the only reason to be
>> thinking about using this in the first place is to keep the cost to a
>> minimum, otherwise, you might as well build a special purpose little
>> box with counters & A/Ds, and an interface)
> I've had too many problems with cheap (onboard) soundcards in the
> past, even when using them for their intended purpose, so I would not
> advice to use them for anything quantitative.
>
> But if you *really* want to syncronize inexpensive soundcards, it's
> rather trivial, see for example
>   http://quicktoots.linuxaudio.org/toots/el-cheapo/ .
>
> Just buy a few dozens for a EUR/$ each and hunt down the ones with
> identical oscillator frequencies ;-). But don't expect miracles, you
> end up with a few synchronized cards that only happen to not skip
> samples with respect to each other. Compared to decent signal input
> they are still cheap cards, and hog the CPU for their individual
> servicing.
>
>    Chris
>
>
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