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

[Poul-Henning Kamp]

In message <4751DAF0.3070700 at xtra.co.nz>, Bruce Griffiths writes:

>The thorny issues of avoiding the noisy environment of a PC and its
>unstable PCI clock whilst still allowing a PC to be synchronised to an
>external timebase may perhaps be adressed by:
>
>Producing a simple PCI (or PCIe, or even ISA bus card - still widely
>used in industry)

You don't need that.

If you have an external timestamping device you can just generate
any relevant signal from the PC (I prefer parallel ports, but they're
going out of vogue) and time that relative to whatever clock your
OS uses, then read back from your timestamping device (via USB ?)
and calibrate accordingly.

Modules cable-length and slope of your generating signal (EMI
filtering), there is no difference in the resulting precision.

BTW: I belive the NI PCI-66xx series of cards can be used also,
but I've never actually tried, I only read the low-level doc.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
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Never attribute to malice what can adequately be explained by incompetence.