Re: ball-hours

From	rickman <gnuarm@gmail.com>
Newsgroups	sci.electronics.design, comp.lang.forth
Subject	Re: ball-hours
Date	2014-10-17 13:53 -0400
Organization	A noiseless patient Spider
Message-ID	<m1rl3o$u54$1@dont-email.me> (permalink)
References	<5sho3adpfhed897nb8jdju99897ouhrvrv@4ax.com> <m1p626$nu5$1@dont-email.me> <caaokmF457jU1@mid.individual.net> <m1ppm6$jvr$1@dont-email.me> <5440d6ad$0$15863$e4fe514c@dreader35.news.xs4all.nl>

Cross-posted to 2 groups.

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On 10/17/2014 4:43 AM, Albert van der Horst wrote:
> In article <m1ppm6$jvr$1@dont-email.me>, rickman  <gnuarm@gmail.com> wrote:
> <SNIP>
>>
>> The GA144 ADCs are just not quite there.  Like I said, they get 15 bits
>> at 48 kHz sample rate.  I don't recall how slow the sampling needs to be
>> to get 16 bits (96 dB nominally).  Likely it is about 12 kHz.
>
> The important point here is that on the GA144 you can get better
> resolution by slowing down, and higher speed by scarificing
> resolution. Or so they say.

Yes, it is an integrator in the true sense.  It has a VFO which is 
controlled by the analog input and increments a counter.  The period is 
set by reading the counter at defined intervals and taking the 
difference.  The VFO curve is not exactly linear, so it needs to be 
corrected in software as well.

The interesting part is that you can add adjacent readings and get the 
same result as if you were reading the counter at a slower rate.  So the 
added resolution can be done in software without changing the actual 
read rate.  If that is set by a stable clock like a crystal it doesn't 
need to be slowed down to have variable rate and resolution.

I think I was confusing two things.  When you are looking at improving 
SNR, adding samples gains SNR by the square root of the number of 
samples.  Gains in resolution are logarithmic with the number of 
samples, so halving the sample rate gets you 1 extra bit meaning the 
GA144 ADCs will get 16 bit resolution around 24 kHz sample rate.

-- 

Rick

Thread

Re: ball-hours rickman <gnuarm@gmail.com> - 2014-10-15 00:25 -0400
  Re: ball-hours bruce.person@gmail.com - 2014-10-14 23:51 -0700
    Re: ball-hours rickman <gnuarm@gmail.com> - 2014-10-15 03:15 -0400
  Re: ball-hours Joerg <news@analogconsultants.com> - 2014-10-15 05:36 -0700
    Re: ball-hours rickman <gnuarm@gmail.com> - 2014-10-15 16:22 -0400
      Re: ball-hours Joerg <news@analogconsultants.com> - 2014-10-15 16:12 -0700
        Re: ball-hours rickman <gnuarm@gmail.com> - 2014-10-15 22:48 -0400
          Re: ball-hours Joerg <news@analogconsultants.com> - 2014-10-16 11:21 -0700
            Re: ball-hours rickman <gnuarm@gmail.com> - 2014-10-16 15:24 -0400
              Re: ball-hours Joerg <news@analogconsultants.com> - 2014-10-16 13:37 -0700
                Re: ball-hours rickman <gnuarm@gmail.com> - 2014-10-16 17:42 -0400
                Re: ball-hours Joerg <news@analogconsultants.com> - 2014-10-17 07:14 -0700
                Re: ball-hours rickman <gnuarm@gmail.com> - 2014-10-17 14:03 -0400
                Re: ball-hours Joerg <news@analogconsultants.com> - 2014-10-17 12:03 -0700
                Re: ball-hours rickman <gnuarm@gmail.com> - 2014-10-17 15:23 -0400
                Re: ball-hours Joerg <news@analogconsultants.com> - 2014-10-17 12:44 -0700
                Re: ball-hours rickman <gnuarm@gmail.com> - 2014-10-17 18:37 -0400
                Re: ball-hours rickman <gnuarm@gmail.com> - 2014-10-16 20:59 -0400
                Re: ball-hours albert@spenarnc.xs4all.nl (Albert van der Horst) - 2014-10-17 08:43 +0000
                Re: ball-hours rickman <gnuarm@gmail.com> - 2014-10-17 13:53 -0400
                Re: ball-hours Joerg <news@analogconsultants.com> - 2014-10-17 07:50 -0700
        Re: ball-hours Raimond Dragomir <raimond.dragomir@gmail.com> - 2014-10-15 20:42 -0700
          Re: ball-hours rickman <gnuarm@gmail.com> - 2014-10-16 01:50 -0400
            Re: ball-hours Raimond Dragomir <raimond.dragomir@gmail.com> - 2014-10-16 00:49 -0700
              Re: ball-hours rickman <gnuarm@gmail.com> - 2014-10-16 05:14 -0400
            Re: ball-hours Joerg <news@analogconsultants.com> - 2014-10-16 11:58 -0700
        Re: ball-hours "Elizabeth D. Rather" <erather@forth.com> - 2014-10-16 08:32 -1000
          Re: ball-hours rickman <gnuarm@gmail.com> - 2014-10-16 15:32 -0400
          Re: ball-hours Joerg <news@analogconsultants.com> - 2014-10-16 13:45 -0700

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