[time-nuts] Of rubidium life and piggy-bank anemia....

Poul-Henning Kamp phk at phk.freebsd.dk
Sat Dec 1 17:51:07 EST 2007


In message <4751E2B2.4000009 at xtra.co.nz>, Bruce Griffiths writes:
>Poul-Henning Kamp wrote:

>Since USB and Firewire ports may persist a little longer, is it possible
>to use similar techniques with these interfaces?

For talking to the timestamping device: certainly.  For signalling
the computers time-edge: no way, they're serial protocols.

>Do you mean that the PCI66XX boards could be used to implement the
>multichannel timestamp function?

Yes, they have counter and latches that I belive a suitable for
at least two signals, but I'm not sure there were any usable
prescalers.  It was a long time ago.

I'm not sure what kind of flanks plastic fibers (as used for instance
from CD-players) have, I might go that route to get complete
electrical separation.

I saw a HP eval kit with 3' of plastic fiber and transmitter and
receiver that would work great.


-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.



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