[time-nuts] Digital Mixing with a BeagleBone Black and D Flip Flop

Magnus Danielson magnus at rubidium.dyndns.org
Sun Oct 12 19:51:57 EDT 2014


Hi,

Some attempts have been made. Never got around to write the needed code.

On 10/12/2014 08:37 PM, Hal Murray wrote:
>
> anders.e.e.wallin at gmail.com said:
>> Does it matter that the ADC in the sound-card is probably clocked by a
>> crystal clock that is 50ppm off and has bad ADEV?
>
> You can calibrate the clock on the ADC.
>
> One way is to feed a known reference frequency in on the other channel.
> (That's assuming you have a stereo setup and don't need the second channel
> for something else.)
>
> Another way is to compare the sample rate with the PC clock.  That will
> correct for any long term drift but may not track shorter transients.
>

Many more professional audio interfaces allows you to supply a 
word-clock, so synthesizing that from suitable source would provide good 
means of adjustment.

48 kHz or multiples is often used.

Cheers,
Magnus



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