[time-nuts] Soundcard sampling Re: Picking a good HP 10811

Lux, James P james.p.lux at jpl.nasa.gov
Wed Dec 3 01:06:45 UTC 2008


>
> You can certainly start with a cheap no name card although
> the noise floor will be somewhat higher (typically a 16 bit
> motherboard sound system is at least 10x noiser than the
> AP192, some have lots of spurs others are quieter). For a
> long enough averaging time the system noise level even with a
> cheap card will be somewhat lower than any OCXO you are
> likely to have.
> A cheap card will at least establish that in principle the
> technique works.
> You can then decide whether to upgrade it.
>
> The AP192 cards only have 2 input channels.
>
> Real AD cards with adequate performance are usually far more
> expensive than $300.
> In principle, one could build an ADC card with adequate
> performance using 4 AD7760 ADCs.
>
> Bruce
>

http://www.hpsdr.com/ Janus module is available built and PCB from TAPR (http://www.tapr.org/)  Has a AKM AK5394 ADC on it, as well as a lower quality DAC. $163 assembled and tested.

http://hpsdr.org/wiki/index.php?title=JANUS

Claiming 120dB SNR, 20bit ENOB at 192ksps



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