[time-nuts] disciplining sound card

Azelio Boriani azelio.boriani at screen.it
Fri Jul 6 23:24:12 UTC 2012


Yes, very smart, this analog time-stamping approach.

On Sat, Jul 7, 2012 at 12:36 AM, John Miles <jmiles at pop.net> wrote:

>
>
> > -----Original Message-----
> > From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> > Behalf Of Azelio Boriani
> > Sent: Friday, July 06, 2012 2:36 PM
> > To: Discussion of precise time and frequency measurement
> > Subject: Re: [time-nuts] disciplining sound card
> >
> > Exactly: this prevented me to buy the ESI Juli@ sound card. It was
> > suggested by a fellow time-nut and this card is indeed very interesting
> but
> > in my opinion sound cards are not well defined about the sampling
> process.
> > I need more details. The Juli@ has the greater than usual bandwidth, not
> > limited to the audio spectrum but up to 90KHz, so it is perfect as a
> > general digitizer for the VLF radio spectrum (DCF77, WWWB and others).
>
> I may have missed some details about the intended use, but in any event,
> the
> latency between the ADC and the software is influenced by a large number of
> factors, some of which will introduce more uncertainty than the pipeline
> characteristics of the ADC itself.  The best workaround might be to couple
> some 1-pps energy into the signal being digitized.  This would effectively
> 'timestamp' the samples at the point where they are acquired, so the
> latency
> would no longer be an issue.
>
> -- john
> www.miles.io
>
>
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