On Tue, 24 Jun 2003, Michael Sierchio wrote:
> Fred Wright wrote:
> 
>  > ...  A Soekris box with a
> > suitable 3.3V GPS clock could make a very economical primary NTP server.
> 
> Possibly, yes...
> 
> http://phk.freebsd.dk/soekris-pps/

So he shows that with the 4501 running from an atomic clock synced to the
PPS signal, the PPS samples are good.  Wow!  What a surprise! :-)
Actually, I think the 4501 *can* do pretty well with this, but I wouldn't
use *that* experiment to prove anything.

He is also depending on controlling one of the GP timers with the PPS
signal, but the inputs with that possibility aren't available on the user
I/O connector.  Although having the PPS signal both interrupt and start a
timer is a fairly ideal way of handling it, it's not possible on an
unmodified 4501, and would also conflict with using all three GP timers
for system timing (which the OS *should* do, but currently doesn't).

> I myself am content at the moment with the UltraLink M325.E,
> supplying timecode and PPS signal to my 4501.  Had to write
> a driver, the existing ulink driver doesn't work.

Using the PPS signal via an interrupt, occasional sampling, or sampling in
a loop?

					Fred Wright