[time-nuts] World's most accurate PC clock!
bg at lysator.liu.se
Sun Jul 3 15:12:20 EDT 2005
This one is WWVB. Interfaces with serial port.
All the time decoding done in software - UNIX/Linux oriented. I bought
the module from
"Rick Karlquist" <richard at karlquist.com> writes:
> Slightly OT: Does anyone know if there is an "atomic clock"
> (the WWVB driven type) that interfaces to a PC via USB or
> something, such that the PC time is regularly updated?
> This would solve my PC time problem. (I need this to work
> w/o internet access).
> Rick Karlquist
> Poul-Henning Kamp said:
> > In message <220.127.116.11.2.20050702233724.04481860 at 18.104.22.168>, "W. D."
> > writes
> > :
> >>Is there a 'HowTo' for this somewhere? How many pins are=20
> >>connected and to where? Where do you mount the chip? Any
> >>batteries involved?
> > This is a little bit beyond "HOWTO" stuff.
> > You need to find a suitable PLL chip. ICST is a major manufacturer
> > of these. Most of them have anti-DYI pin-spacing though.
> > Then you need to locate the Xtal on your motherboard which drives
> > the clocks. Again, a good place to start is to look for a PLL
> > chip from ICST. Usually there is a 14.318MHz xtal right next
> > to that, but some botherboards use different frequencies these
> > days and generate the 14.318MHz by PLL instead.
> > You can then either remove the existing xtal and feed your signal
> > to the right of the two holes (experiment or read datasheet for
> > the on-board PLL chip) or you can try override it while it remains
> > on the motherboard by feeding your signal into it. Overriding
> > gives jitter and most modern motherboards don't like that.
> > --
> > 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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