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Re: GA144 polyForth

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On 10/14/2012 5:00 AM, Howerd wrote:
> On Saturday, October 13, 2012 11:30:44 PM UTC+2, rickman wrote:
>>
>
> Hi Rick,
>
>> Then you are looking for resolution, not VCO speed.
> I am looking for both - detection of very small signals and very small time intervals.

In the GA144 the time interval will be determined by the CPU speed, I 
think the best you might get is around 10 ns, but I don't recall 
exactly, this might be for a clock timed loop that just takes the data 
and passes it on.  At that speed you will only get 4.3 ENOB (effective 
number of bits) theoretical max.  That's not very sensitive.


>> Many other ADCs will give you very high resolution as well.
> Digital resolution, yes, but analog resolution probably not.

Uh, yeah...  right.  It's time to learn about electronics.  You can 
think that you are going to toss existing theory out the window, but 
this is not the area that needs to be reinvented in order to learn 
about... what was it you were exploring again?


>> GA144 ADC for high resolution at very slow sample rates.
> I think you are using "resolution" in two different ways - there is analog resolution ( ability to detect a given change in voltage ), and ADC resolution ( number of bits ).

Yes, they are related by the gain of your amplifiers... uh, if you had 
amplifiers.  In the GA144 integrating ADC the analog resolution will be 
related to the sample rate...  if you have a sample rate.  The faster 
the sample rate the lower the analog resolution.  The 4.3 bits I mention 
above are over the analog range of about 1.2 volts, this is not well 
defined in the data sheet, so I'm not certain what this range is.  The 
ADC has a non-linear curve with more resolution in the center which is 
what I am assuming will be used.  Trying to get the full analog range of 
1.8 volts uses the compressed ranges near the limits with very low 
analog resolution.

The digital resolution is the number of bits.  The analog resolution is 
the analog range divided by the number of bits.  No magic, no new 
science to be invented.  The two are directly connected.  The only way 
to improve the analog resolution is to slow down the measurement to give 
longer integrations or to use an amplifier to get the same voltage range 
at the ADC input with a smaller range on the amplifier input.


>> The rate of the VCO is not the sample rate of the ADC
> It is if it is a 1-bit ADC, sort of.

Ok, you can go ahead and think of this as a 1 bit ADC but that buys you 
the worst possible resolution at the highest sample rate.


> Its the analog resolution that I am interested in. I presume that the GA144's VCO is just a handful of transistors, so the bottom bit of the VCO count represents some very small change in the charge at the input pin.

No, the counter bits do NOT correspond to anything at the input.  The 
counter free runs at a rate between about 3.5 GHz and 5.5 GHz.  The raw 
readings just keep incrementing and the absolute values mean nothing. 
You get an ADC reading by SUBTRACTING one reading from the next.  This 
DIFFERENCE is proportional to the integral of the voltage at the input 
over the sample period.

Actually, the range of the VCO in the linear area is only about 1.3 or 
1.4 GHz rather than the 2 GHz I used to calculate the ENOB.  The 
frequency range is what determines the difference range and the ADC 
resolution.


> Only with the GA144 do I get very sensitive analog inputs together with some fast processing, plus a high level (eForth or polyForth) IDE, all on chip.
> I think this is magic :-)

Yes, I expect it must seem like magic...  Or you could listen to people 
who don't see it as magic, but rather understand the details and can 
explain how it works as if it were engineering...

I'm pretty sure you won't see anything in your signals using the GA144 
that you can't see as well if not better using other devices.  For 
example, how well will your readings be time correlated using multiple 
ADCs in the GA144?  I can't get an answer to questions like this.  Or 
even how long the GA144 nodes take to come out of sleep when the input 
clock transitions.  These are *very* important numbers when using the 
ADC for signal acquisition.  Random delays here cause signal 
distortion/noise.

Rick

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Thread

GA144 polyForth Howerd <howerdo@yahoo.co.uk> - 2012-09-27 14:16 -0700
  Re: GA144 polyForth Paul Rubin <no.email@nospam.invalid> - 2012-09-29 01:20 -0700
    Re: GA144 polyForth rickman <gnuarm@gmail.com> - 2012-09-30 11:05 -0400
      Re: GA144 polyForth Paul Rubin <no.email@nospam.invalid> - 2012-09-30 09:06 -0700
        Re: GA144 polyForth rickman <gnuarm@gmail.com> - 2012-09-30 14:29 -0400
          Re: GA144 polyForth Paul Rubin <no.email@nospam.invalid> - 2012-09-30 19:56 -0700
    Re: GA144 polyForth Coos Haak <chforth@hccnet.nl> - 2012-09-30 21:54 +0200
    Re: GA144 polyForth Howerd <howerdo@yahoo.co.uk> - 2012-10-01 11:18 -0700
      Re: GA144 polyForth Paul Rubin <no.email@nospam.invalid> - 2012-10-01 23:40 -0700
        Re: GA144 polyForth "Elizabeth D. Rather" <erather@forth.com> - 2012-10-01 21:23 -1000
          Re: GA144 polyForth albert@spenarnc.xs4all.nl (Albert van der Horst) - 2012-10-05 19:19 +0000
        Re: GA144 polyForth Howerd <howerdo@yahoo.co.uk> - 2012-10-04 23:04 -0700
  Re: GA144 polyForth Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-10-01 10:28 -0500
    Re: GA144 polyForth Howerd <howerdo@yahoo.co.uk> - 2012-10-01 11:19 -0700
      Re: GA144 polyForth Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-10-03 10:46 -0500
        Re: GA144 polyForth Howerd <howerdo@yahoo.co.uk> - 2012-10-04 13:46 -0700
  Re: GA144 polyForth Howerd <howerdo@yahoo.co.uk> - 2012-10-05 22:10 -0700
    Re: GA144 polyForth Paul Rubin <no.email@nospam.invalid> - 2012-10-05 23:17 -0700
      Re: GA144 polyForth Howerd <howerdo@yahoo.co.uk> - 2012-10-06 05:47 -0700
        Re: GA144 polyForth rickman <gnuarm@gmail.com> - 2012-10-07 19:31 -0400
          Re: GA144 polyForth Bernd Paysan <bernd.paysan@gmx.de> - 2012-10-08 20:10 +0200
            Re: GA144 polyForth rickman <gnuarm@gmail.com> - 2012-10-08 16:36 -0400
          Re: GA144 polyForth Howerd <howerdo@yahoo.co.uk> - 2012-10-08 13:31 -0700
            Re: GA144 polyForth rickman <gnuarm@gmail.com> - 2012-10-09 13:48 -0400
              Re: GA144 polyForth Howerd <howerdo@yahoo.co.uk> - 2012-10-09 13:21 -0700
                Re: GA144 polyForth rickman <gnuarm@gmail.com> - 2012-10-09 17:08 -0400
                Re: GA144 polyForth Howerd <howerdo@yahoo.co.uk> - 2012-10-13 07:39 -0700
                Re: GA144 polyForth rickman <gnuarm@gmail.com> - 2012-10-13 14:28 -0400
                Re: GA144 polyForth Howerd <howerdo@yahoo.co.uk> - 2012-10-13 13:37 -0700
                Re: GA144 polyForth rickman <gnuarm@gmail.com> - 2012-10-13 16:54 -0400
                Re: GA144 polyForth Howerd <howerdo@yahoo.co.uk> - 2012-10-13 14:14 -0700
                Re: GA144 polyForth rickman <gnuarm@gmail.com> - 2012-10-13 17:30 -0400
                Re: GA144 polyForth Howerd <howerdo@yahoo.co.uk> - 2012-10-14 02:00 -0700
                Re: GA144 polyForth rickman <gnuarm@gmail.com> - 2012-10-14 19:54 -0400
                Re: GA144 polyForth Howerd <howerdo@yahoo.co.uk> - 2012-10-15 11:03 -0700
                Re: GA144 polyForth rickman <gnuarm@gmail.com> - 2012-10-15 16:38 -0400
                Re: GA144 polyForth Howerd <howerdo@yahoo.co.uk> - 2012-10-16 04:12 -0700
                Re: GA144 polyForth rickman <gnuarm@gmail.com> - 2012-10-16 15:46 -0400
                Re: GA144 polyForth Howerd <howerdo@yahoo.co.uk> - 2012-10-16 23:05 -0700
                Re: GA144 polyForth rickman <gnuarm@gmail.com> - 2012-10-17 13:40 -0400
                Re: GA144 polyForth Howerd <howerdo@yahoo.co.uk> - 2012-10-17 22:54 -0700
            Re: GA144 polyForth rickman <gnuarm@gmail.com> - 2012-10-18 14:53 -0400
              Re: GA144 polyForth rickman <gnuarm@gmail.com> - 2012-10-18 15:06 -0400
                Re: GA144 polyForth rickman <gnuarm@gmail.com> - 2012-10-18 15:09 -0400
              Re: GA144 polyForth Howerd <howerdo@yahoo.co.uk> - 2012-10-19 10:43 -0700
                Re: GA144 polyForth rickman <gnuarm@gmail.com> - 2012-10-19 17:43 -0400
  Re: GA144 polyForth Mikael Nordman <oh2aun@invalid.com> - 2012-10-06 11:29 +0300
    Re: GA144 polyForth mhx@iae.nl (Marcel Hendrix) - 2012-10-06 11:14 +0200
      Re: GA144 polyForth Mikael Nordman <oh2aun@invalid.com> - 2012-10-06 16:08 +0300
    Re: GA144 polyForth Paul Rubin <no.email@nospam.invalid> - 2012-10-07 10:57 -0700

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