AW: [time-nuts] Accuracy of a sound card

Ulrich Bangert df6jb at
Tue Aug 23 11:08:42 EDT 2005


it isn't exactly the time to talk about, because not everything is
working as expected, but since you started with sound card accuracy:
Since a few months i am working on a project that uses a sound card as a
phase comparator behind a dual mixer for ultra stable oscillator
stability measurements. 

Because it is a differential measurement between the two channels (which
are sampled exactly the same time due to the adc hardware) the first
idea was, that the effects introduced by the not so good sample clock of
a ordinary sound card may cancel out completely. 

Unfortunately this is not the case. For that reason i bought a sound
card, which's sample clock can be phase locked to a external signal, a
M-Audio Delta Audiophile 192. In the (semi)professional musician's world
it is somtimes necessary to get some sound cards synchronized. Currently
i am working on a circuit that produces a S/PDIF signal phase locked to
a 10 MHz standard frequency which in turn the sound card can phase lock
on. You may imagine that the utility you wrote is more than welcome for
the tests that i have in front of me. Can you send it?

Best regards
Ulrich Bangert

> -----Ursprüngliche Nachricht-----
> Von: time-nuts-bounces at 
> [mailto:time-nuts-bounces at] Im Auftrag von Tom Van Baak
> Gesendet: Montag, 22. August 2005 18:33
> An: Time Nuts
> Betreff: [time-nuts] Accuracy of a sound card
> I measured the phase, frequency and Allan deviation of
> the sound card on my cheap PC. You'll enjoy the results:
> If any of you with a high-end sound card want to repeat
> the experiment let me know.
> /tvb
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