[time-nuts] Using cheap sound cards for measurements

John Miles jmiles at pop.net
Fri Aug 21 21:24:32 UTC 2009


That particular method is vulnerable to a lot of things. :-P

-- john, KE5FX

> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com]On
> Behalf Of Bruce Griffiths
> Sent: Friday, August 21, 2009 2:20 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Using cheap sound cards for measurements
> 
> 
> 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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