On Sat, Aug 24, 2019 at 10:31 PM Attila Kinali <[email protected]> wrote: <snip>
> Another important thing to know with audio ADCs is, that they are > almost always some sigma-delta variant. This gives them a high linearity > and low noise with moderate cost. But that also means that the higher > the bandwidth you are using, the higher the noise floor becomes, as > you are "averaging" over less and less samples. I.e. while an audio > ADC might be spec'ed to be sampling at 192kHz, you will be only able > to use up to 20kHz with the nice low noise floor that is specified. > If you go beyond that, you will have a corresponding increase in > noise. > That really depends on the order of the modulator and the digital filter. Compare, for example, figure 18 of the PCM4222 data sheet ( http://www.ti.com/general/docs/suppproductinfo.tsp?distId=10&gotoUrl=http%3A%2F%2Fwww.ti.com%2Flit%2Fgpn%2Fpcm4222 ) with figure 2.1.3 of the AK5394 dev board manual ( https://www.akm.com/akm/en/file/ev-board-manual/AK5394AVS.pdf ). And while there may be some flicker noise present, I've not personally seen the poor DC performance in many S/D audio converters either (apart as artefacts from the front-end electrolytic coupling capacitors). JDB [The SDR community has rather a bit of experience with using audio ADCs as generic samplers, before faster converters were feasible.] _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
