[ntp:questions] Re: Toggling time sync between two servers
Richard B. Gilbert
rgilbert88 at comcast.net
Mon Mar 27 04:46:14 UTC 2006
> Thanks. In this application, a few thousand dollars is not going to be
> an issue. Having the correct time is critical and that is why I'm
> hoping that managment will go for it. I believe the two sources we
> have now are from GPS.
Can you locate an antenna where it will have an unobstructed view of the
entire sky? If so, you can buy a GPS receiver (GARMIN GPL18LVC) for
less than $100 and connect it to a serial port on a computer running
ntpd with support for refclocks and presto! It's a bit on the do it
yourself side of things but it will get the job done. You'll need a
soldering iron, a DB9 connector, and a five volt power supply.
Moving upscale a bit, you can get a Motorola Oncore M12M timing receiver
(actually somebody else makes them now) from Synergy Systems. You get
the one with the evaluation board. It's still pretty crude; a bare
circuit board, but a power supply, antenna, and RS232 cable come with
it. That will cost you $200. Plug it in, connect it to a serial port,
install ntpd, configure it, and go.
Moving pretty far upscale, you can get a box from Symmetricom with a
built in GPS receiver and NTP server. Plug it in to the AC outlet and
your Ethernet. I think these go for something like $2500 and up.
That's about $2300 above my budget for toys so I don't have one and
won't unless someone gives me one for Christmas. I think that box may
also come with an OCXO disciplined by the GPS to give some "holdover"
capability if you lose signal from the satellites.
You can also get a box that gets the time from a CDMA Cell Phone base
station (derived from GPS). You plug that box into AC, your network and
a whip antenna. It, too, has a built-in NTP server.
You might want to get a couple of each.
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