[time-nuts] 31bit ADC, 1000 samples per second

Azelio Boriani azelio.boriani at screen.it
Mon Dec 10 15:54:53 UTC 2012


I see that there is a high resolution 130dB mode too that can give 21 bits
@ 250 samples per second, good for very slow, high resolution DMTD (but
also very stable voltage reference and ADC temperature, seems very
challenging).

On Mon, Dec 10, 2012 at 4:26 PM, Robert LaJeunesse <
rlajeunesse at sbcglobal.net> wrote:

> 31 bits is just a convenient word size that comes out of the on-chip
> filter, and
> does not really relate to performance. Better to look at SNR which, at
> worst
> case, is 120dB in high-res mode. That indicates performance just under 20
> bits,
> typical for better monolithic sigma-delta converters. Nonetheless 20 bits
> indicates a matching reference would have to hold 1PPM over temperature, no
> simple task.
>
>
> Bob LaJeunesse
>
>
>
> ________________________________
> From: Azelio Boriani <azelio.boriani at screen.it>
> To: Discussion of precise time and frequency measurement <
> time-nuts at febo.com>
> Sent: Mon, December 10, 2012 9:39:30 AM
> Subject: Re: [time-nuts] 31bit ADC, 1000 samples per second
>
> 31-bit is 186dB... with what do you compare that device? What kind of
> reference is needed?
>
> On Sun, Dec 9, 2012 at 11:18 PM, Bob Camp <lists at rtty.us> wrote:
>
> > Hi
> >
> > It's the "big brother" of the ADS127x parts that I mentioned a little
> > while back. I'm sure it works quite well. The 127x's are fine parts. The
> > internal filtering combined with the chopper is a very nice combination.
> >
> > Bob
> >
> > On Dec 9, 2012, at 5:13 PM, Poul-Henning Kamp <phk at phk.freebsd.dk>
> wrote:
> >
> > >
> > > I'm doing some work with a couple of geophones (long story...) and
> > > stumbled across TI's ADS1282 geophone ADC.
> > >
> > > It has some pretty amazing specs for low frequencies, and having played
> > > with the EVAL board for an evening here in my lab, I'm pretty
> impressed.
> > >
> > > People working with close-in phase-noise measurements may want to
> > > consider this chip...
> > >
> > > --
> > > Poul-Henning Kamp      | UNIX since Zilog Zeus 3.20
> > > phk at FreeBSD.ORG        | TCP/IP since RFC 956
> > > FreeBSD committer      | BSD since 4.3-tahoe
> > > Never attribute to malice what can adequately be explained by
> > incompetence.
> > >
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