[time-nuts] lunatic fringe time standards

Bob Camp lists at rtty.us
Thu Apr 15 07:30:27 EDT 2010


Hi

I'm not 100% sure I understand exactly what you are thinking about setting up. My guess is that the counter needs to run at the same THz speed as the oscillator. That's pretty fast. I suspect that what ever you use, speed / propagation delay in the counter it's self will be an issue. That will get you back to either a ripple counter or a Johnson counter. 

Bob


On Apr 15, 2010, at 7:07 AM, Eugen Leitl wrote:

> On Thu, Apr 15, 2010 at 02:48:58AM -0700, Hal Murray wrote:
> 
>> I'm not aware of anything like I think you are describing.
>> 
>> What problem are you trying to solve?
>> 
>> The main reason that I think of using gray codes is for crossing clock 
>> domains.
>> 
>> But as Magnus pointed out, another possible problem is just counting at high 
>> speeds.
> 
> I was idly musing about how to reliably count an integrated solid-state
> THz oscillator adjacent to a (very wide) counter. The problem is due 
> of relativistic signal delays which are in the ballpark of counter
> feature size. A way to circumvent that is to keep relevant state changes
> to the oscillator lightcone. Hence Gray codes with local bit flips,
> or something similar.
> 
> The compensation for drift and e.g. relativistic (spacetime curvature
> and motion) effects would happen by directly applying small numerical
> deltas to the ALU downstream of the counter. The result would be a
> clock directly compensated against movement and position in a gravitation
> well.
> 
> -- 
> Eugen* Leitl <a href="http://leitl.org">leitl</a> http://leitl.org
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