[time-nuts] Using cheap sound cards for measurements

[Demian Martin]

Modern soundcards using stereo DACs have very little shift between the
channels. Usually much less than a sample period, probably less than m-clock
period (64 to 256 X the sample period). And a high res card at 24 bits
(probably 20 usable) will give you a lot of data to chew on.



Demian Martin
Product Design Services 

Date: Fri, 21 Aug 2009 22:06:28 +0000
From: Mark Sims <holrum at hotmail.com>
Subject: [time-nuts] Using cheap sound cards for measurements
To: <time-nuts at febo.com>
Message-ID: <BLU125-W21D283C0DFE19FDB6641A7CEFC0 at phx.gbl>
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Just because the cards have the same ADC clock does not mean that they will
be sampling at the same time.  There will be differences in the startup
characteristics,  register programming, etc.  that can affect just when the
input is sampled.  They may be sampling at the same rate,  but the cards
could be an indeterminate number of cycles off from each other.