Feeding GPS Time to a Private NTP Server?

farrellj asks: "I have a customer that wants to be able to sychronise time on hundreds of servers that are spread all across the continental US and Hawaii. He was using publicly accessable NTP servers, but would rather have his own server that is not dependant on outside servers, and not have to worry about NTP based attacks. You can get a good quality and accurate time from GPS, so he looked at using a GPS reciever hooked up to a machine in his server room, but none of the GPS software out there seem to be able to just pull out the time, and then feed it to an NTP server. Has anyone tried to do this before, or know of a program that will read at GPS reciever and feed it to a NTP server process?"

Comments

er.

[OnyxRaven]

I know of at least one package I've used in a completely different situation that can pull down the datetime and gps reading through the serial connection, and has a programming API. Now, this was in windows but I'm sure its available for flavors of unix as well.

Trimble's Pathfinder. If you need some code I may be able to dig some up. A warning, it'll be in VB, but it works.

GPSD

[agentk]

I use Remco Treeffkorn's GPSD to read data off of GPS devices in my tracking library (libtracking-- see interreality.org)

http://russnelson.com/gpsd/

Hows about this?

[olrs]

This is the result of a quick googleing. Have you looked at this type of product? http://www.lantronix.com/products/nts/ntpe1_tr1/in dex.html

NMEA

[Bernaps]

Buy a Serial Data GPSAnd Grep the detail from the output.

Little Program can easily be found on google (search NMEA GPS).
List of Progs

Here is a simple one

Two Standard Exist for the GPS Output NMEA. Most can provide this information via RS232

Less Than 20 Char to read from the Port. Automatically received once per second. Parse the data with PERL/AWK/SED/JAVA/C it's very simple.

Use the standard Unix NTP d�mon: nptd ...

[geirt]

Use the standard NTP dæmon in RedHat, Debian and other called ntpd

Ntpd supports many GPS reference clocks directly, so you don't need any special software to "pull out the time, and then feed it to an NTP server".

www.ntp.org

[hawkfan]

ntp.org. Did you even look? There are plenty of gps recievers capable of providing a pps signal to ntpd.

gps+ntp in a box

[tim pickering]

http://www.endruntechnologies.com/

they have boxes that sync off of either gps or cdma (for those places where you can't get a good view of the sky). the gps model with the stock oscillator can go several hours without satellites before it drifts too far and only needs a single satellite rather than a full multi-sat lock to sync its clock. upgraded oscillators are available for better and longer term stability. we use the gps version at our observatory to provide ~1 ms time over the network via ntp and ~10 us or better time via the PPS and kPPS outputs. we looked into hooking external gps receivers to PCs running ntpd via serial and PPS, but these praecis boxes are a much easier to configure and maintain solution to the problem and likely more robust as well.

tim