NTP clock source

Thu Mar 25 14:03:22 UTC 2010

On Thu, Mar 25, 2010 at 12:51 UTC, Kyle Bader <kyle.bader at gmail.com> wrote:
> Can anyone recommend a solid clock souce (stratum 0) that's not overly
> expensive?

All the options I'm aware of have no prices posted, sadly.  For me,
that means "forget it, you don't want to spend that much", but then
I'm not spending other people's money :)

In addition to Symmetricom and EndRun Technologies, Meinberg has a
solid reputation in this space:

http://www.meinberg.de/english/products/#network_sync

I'm biased toward Meinberg because several of their staff contribute
their skills to the development and maintenance of the ntp.org
reference implementation.  They have also been generous donating
hardware over the years to ntp.org and pool.ntp.org, and their Windows
NTP binaries and GUI installer are widely used.

The cheapest solution involves the Garmin GPS 18x LVC receiver and a
soldering iron.  Unlike the USB and "PC" (232) versions of the GPS
18x, the LVC version supplies a pulse-per-second signal which makes it
suitable for sub-millisecond NTP sync.  The supplied connector has to
be cut off, a DB-9 serial hood wired in its place, and either a USB
cable or other 5V power supply needs to be attached.  Or you can do as
I did and pay for the completed GPS 18x LVC with DB-9 and USB
connectors from a third party.  $105 from:

http://psn.quake.net/gps/gps18.html

You also need a junkbox PC with real serial ports (not via a USB
adapter), or the capacity on an existing server.  The GPS 18x cable is
either 3m or 5m long, if your PC is not close enough to a
southern-exposed window or to roof access for the 18x to lock, you may
also need a RS-232 extension cable and USB power supply.  Unlike
timing-focused GPSes, the 18x needs 3 or more birds in view to provide
a PPS signal.

Good luck,
Dave Hart