[time-nuts] Thunderbolt? (re simple gpsdo.)

Chris Albertson albertson.chris at gmail.com
Sat Dec 31 06:01:38 UTC 2011


On Fri, Dec 30, 2011 at 10:16 AM, Hal Murray <hmurray at megapathdsl.net> wrote:
>
>> "What is the simplest design for a GPSDO that uses only the PPS signal from
>> a modern GPS?"
>
> Some sort of oscillator with a voltage control.
> CPU with a timer/counter that can capture the PPS.
> DAC.
> Software.

As soon as you say "Software" the device is no longer simple.    Even
a microprocessor is a very complex device and so is its development
system.   The software inside the uP is not simple either if you count
the number of possible paths through the code (2 raided to the power
of the number of branches.)

I have nothing against software, that is what I do for a living, every
day.  But you can't count a uP with software indise as "simple".
And the point of this exercise is to find the simplest thing that can
still work.
Chris Albertson

Redondo Beach, California




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