Hi!
I am looking for a solution to install an NTP server in a very
restricted network which can not be connected to other networks even
through a firewall because of strict security policy. RS232 and usb are
ok. Using GPS or DCF77 reference clocks would require a long antenna
wire to get signal. Installing the antenna cable would be expensive, but
there is good LAN cabling between a space with good GPS signal and the
room with high security.
What kind of cheap solutions would you think of? For instance, is it
possible to feed time signal from one NTP server to another via
RS232/usb? Or is there an affordable usb/rs232 reference clock which has
an IP based separate antenna unit?
With best regards,
--
Cristian Seres
Cristian,
I would consider installing a GPS puck (such as the GPS 18x LVC or Sure
Electronics board) in the antenna space, and use the LAN cabling to
distribute the RS-232 signal with PPS from the GPS to your NTP server PC
(or multiple PCs). If needed, you could use line drivers and receivers to
improve the signal integrity on a long cable run, and to distribute the
PPS component of the signal to multiple server PCs.
https://buy.garmin.com/shop/shop.do?pID=223
https://buy.garmin.com/shop/shop.do?pID=27594&pvID=14555
http://www.sureelectronics.net/goods.php?id=99
Example of use:
http://www.satsignal.eu/ntp/Sure-GPS.htm
Once you have one or two stratum-1 servers, the rest can be synced over
the LAN to within a few milliseconds, if that's good enough.
Cheers,
David
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