Can anyone recommend a solid clock souce (stratum 0) that's not overly
expensive? The only stuff I've found so far is ESE, can anyone
recommend them or conversely has anyone had any problems with their
hardware?
Can you clarify your requirements when you say stratum 0? Accuracy, holdover time, needed outputs, do you want a standalone box or something that you plug in to an existing computer or router?
-Dave
You can look at the Tempus LX line from Endrun Tech. if a GPS based NTP server will work for you. They also have a CDMA version.
http://www.endruntechnologies.com/time-server.htm
HTH
G
Can anyone recommend a solid clock souce (stratum 0) that's not overly
expensive? The only stuff I've found so far is ESE, can anyone
recommend them or conversely has anyone had any problems with their
hardware?
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
I use both EndRun Technologies and the "Garmin 18x LVC + old PC" solution.
I am currently seeing 8+ satellites out a North facing window almost
all of the time with the Garmin. The window method may not work if the
window is coated with a metallic layer (common in newer buildings).
Also, be careful extending the serial line. The rise time of the PPS
signal is already degraded by the length of wire that is supplied.
Jon
Kyle Bader wrote:
Can anyone recommend a solid clock souce (stratum 0) that's not overly
expensive? The only stuff I've found so far is ESE, can anyone
recommend them or conversely has anyone had any problems with their
hardware?
If you are of the DIY persuasion, check out the following project:
http://www.febo.com/pages/soekris/
-M
Garmin 17HVS mounted on the top of the building attached to a old HP thin client (SSD with no fans) running FreeBSD.
After implementation, I haven't thought about it since.
Thanks,
Erik
We have several symmetricom time servers that we use in several location and I'd recommend them very highly.
-d
The Endrun Technologies product worked well for me. After an initial
set-up, it was maintenance free. I couldn't install a rooftop antenna
so I needed the CDMA receiver.
http://www.endruntechnologies.com/network-time-server.htm
Nate Itkin
And if the OP (or any one else on list) is of that persuasion, and really
wants to get into serious timing discussions, joining the time-nuts mailing
list at febo.com would be a good idea.
And if Stratum 0 is a requirement, then looking at the time-nuts archives at
least would be good preparation for running a real Stratum 0 time source.
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 moneyIn addition to Symmetricom and EndRun Technologies, Meinberg has a
solid reputation in this space:Time and Frequency Product Range - Overview
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.
I totally agree! Meinberg's M300's rock solid and JTime is really easy
to deal with as are its distributor's.
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:
True - you can build very accurate timekeeping service practices, but
ALL GPS-L1 based systems have one flaw - the provability of the time
data is squat. The evidence-model from a passive L1 system no matter how
accurate it is - is zero... zip... it has as much legal impact with a
competent lawyer on the other side, as you looking at mickey on your
wrist and setting the ToD by hand daily.
This is becoming more and more important in the world of commercial
computing and something that timekeeping will have to morph towards to
insure its not unseated...
Can anyone recommend a solid clock source (stratum 0) that's not overly
expensive? The only stuff I've found so far is ESE, can anyone
recommend them or conversely has anyone had any problems with their
hardware?
Why would you want a S-0 Clock??? You are not a time-space lab, and so
you would want something like a stratum-2 time source which comes from a
provable provider. There are laws by the way on what are official and
non-official sources of time. In the US for instance these are 15 USC
271 and 272, and the right to deploy the time is codified in 15 USC 260
so which source of time is used is important.
By the way - if this is a commercial use, try applying the same set of
controls to the time provider you are forced to apply to the rest of the
outsourcing service providers you rely on...
--
Kyle
We have several symmetricom time servers that we use in several location and I'd recommend them very highly. '
Depends on whether you are trying to generate evidence of something or
not. If you need to be able to prove the time data is correct, then you
will need a process to do that, a process which most all of the time
server systems to date choke on pretty badly.
Since the GPS-L1 system without SAASM encryption was formally banned by
the US Military for use in their systems by an order of the Joint Chiefs
of Staff in 1998, its pretty clear that relying on GPS-L1 for anything
requiring a sense of digital trust is out.
NTP Peer Stats files have virtually no way of associating content to
events meaning that the time-tokens which are passed around are lost in
the wind, meaning that there is no enduring evidence generated by NTP.
The NTP loopstat and peerstat files have just enough info to be
dangerous and not enough to prove anything to the existing rules of
evidence, so the real issue is whether you have to prove something as a
response to a regulatory requirements or you just want to synchronize
the systems in question for...
Todd
Actually reading sections 260, 271, and 272 doesn't seem to actually talk
much about it, and unless you really care in a legal sense if your time is
derived from a WWVB signal or a GPS clock, it probably doesn't matter. OK,
maybe if you're listening to the Canadian radio signal, or the European
competitor to the GPS constellation it matters. Does anybody *really* care,
given that all these sources are usually synced to each other well enough that
it doesn't matter accuracy-wise?
The reason he wants a stratum-zero clock source is because when he sets up his
server that reads from that clock, it will in NTP-speak end up being a
stratum-1 clock, which is what he wants to deploy, then when he distributes it
to other servers, they'll become the stratum-2 clocks you mention.