[ntp:questions] Thunderbolt at NTP ref clock.

DaveB spam.goes at nowhere.com
Thu Aug 1 19:11:10 UTC 2013

In article <ktcujr$vpc$1 at dont-email.me>, david-
taylor at blueyonder.co.uk.invalid says...
> On 31/07/2013 20:36, DaveB wrote:
> []
> > The server is using 5 'net based servers at this time (my original GPS
> > RX died) and is only just stable enough for what I'm doing.  Sometimes
> > due to asymetric ping times, it "wanders a bit" for an hour or three.
> []
> > Oh...  Though the time server is FreeBSD based, other boxes in my empire
> > are a mixture of Windows and Linux, various versions types and
> > requirements.
> >
> > Cheers All.
> >
> > Dave. (G0WBX/G8KBV)
> Dave,
> A small GPS with PPS I can recommend to you is this one:
>    http://www.adafruit.com/products/746
> At least here, on the top floor of a two-storey house in Scotland, it 
> gets enough signal to lock consistently.  Not too expensive, and 
> available from a UK stockist.
> http://proto-pic.co.uk/ultimate-gps-breakout-66-channel-w-10-hz-updates-mtk3339-chipset/
> A few hundred microseconds should be enough for your pulse, although 
> GPSs tend to use either 100 ms or 200 ms by default.  Easier to see on a 
> non-storage 'scope as well!  I'm pondering on making a driver and having 
> a terminated line running around the shack here (at pseudo RS-232 
> levels) for feeding PPS into all my PCs which have COM ports to get the 
> best time synchronisation.  AT the moment, those PCs which aren't 
> stratum-1 have the poll interval set to 32 seconds to the local 
> stratum-1 servers.
> I'm sure you know about the information on my site for FreeBSD, Windows 
> and Linux, but others may not:
>   http://www.satsignal.eu/ntp/index.html

Yes, well aware of your wonderful resource pages.  And thanks for the 
link to the adafruit site, I'd forgotten about them.

I now have a new-old-stock GPS-16 (with unmolested full length lead and 
original connector) should I need, but I may end up using that for 
similar needs in a mobile setting, hence my interest in using the TB to 
drive the shack NTP box.

Took a look at the TB's PPS signal last night, & yes, 20ns duration, and 
though it can be turned -ve (as in 0 to -5V) or off, the width can't be 

Too many toys, so little time. :)



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