On 05/12/2010 08:47 AM, Eugen Leitl wrote:
Has anyone utilized a network of locally, weakly coupled oscillator synchronization (a la http://www.projectcomputing.com/resources/sync/index.html ) for precise timekeeping purposes?
You have to realize that if you have N clocks interlocked, then their common frequency will tend to the average or weigthed average (if coupling is not the same). A single clocks deviation will not have full effect. It will help to solve phase noise if you monitor the full ensamble of clocks, but this effect is best at short-term stability.
It will not solve any form of common environmental effects such as temperature shifts. Mother earth turns, if faces the sun or the dark space. AC equipment may first-degree correct for it, but their cycling will replace it. The environmental effects would dominate iin the time-spans we would be interested in.
So in the end, many oscillators isn't as powerful as it may sound at first. For a network, the solution is to let some nodes have considerable better oscillators and steer the clock selection accordingly. This is what is done in SDH networks. See for instance ITU-T G.781. There is a tutorial from ETSI which designation just slipped my mind.
The use of mutually synchronised oscillators was investigated in the telecom world. I don't recall that anything useful came out of that, but searching for "mutual synchronisation" should get you some hits. I could dig up a few articles if you care to read about it. I consider it a dead end for the above reasons.
Cheers, Magnus _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
