Hi Ok, how long will this driving around take?
If you are driving continuously with no GPS for 24 hours, your system needs to hold 100 ms for 86,400 seconds. With a fixed frequency offset (rather than drift) that’s 0.1 / 86400 = 1.12 ppm. If you want to spend money. Modify the clock in one or more of your PC’s to run off of a cheap TCXO. Make those PC’s the “head ends” of your empire. Set it up as Chris suggests and move on. NTP has all the “stuff” in it to work out the frequency offset of the TCXO and take care of any drift. Cheap, easy, redundant, reliable … what’s not to like :) Bob > On May 31, 2015, at 5:50 AM, Chris Albertson <albertson.ch...@gmail.com> > wrote: > > If you already have a bunch f PCs running NTP why add one more? Just > run the PPS from your GS to one of the existing PCs Anklet t be a > stratum one. It's zero cost. For hold over "Orphan mode" works well > and will meet your 100 ms requirement. Again, it is zero cost. > > On Sat, May 30, 2015 at 3:53 AM, David J Taylor > <david-tay...@blueyonder.co.uk> wrote: >> Hi sorry for a possibly OT post. >> Has anyone had practical experience with small commercially available time >> servers / ntp servers suitable for mobile use in a vehicle. >> >> The use case is I am in need of an accurate (ie. within 100 ms) time source >> for several pc's in moving vehicle. Being able to run directly off a 13.8 >> or 28 VDC source would be a major plus but AC power is also available. >> >> Hold over if there are gaps in GPS coverage is also a major plus. >> >> We already have a GPS with a 1 pps output, but an integrated box with it's >> own GPS would be best. >> >> Yes I am aware I could feed a 1 pps signal into a laptop and use that as a >> time server and I may end up going that route. >> >> There is a small Ethernet LAN in the vehicle. The pc's currently get their >> time via a wireless connection to various NTP servers. I need to be able >> to ensure accurate time on the PC's if there is no wireless coverage. >> >> >> This is for a one off project so piecing together various parts is an option >> but a single box COTS solution would be nice. I've found a few candidates >> via web searches but would welcome any feed back. >> >> Thanks in advance >> >> Mark Spencer >> _______________________________________________ >> >> >> Raspberry Pi perhaps? >> >> http://www.satsignal.eu/ntp/Raspberry-Pi-quickstart.html >> >> Cheers, >> David >> -- >> SatSignal Software - Quality software written to your requirements >> Web: http://www.satsignal.eu >> Email: david-tay...@blueyonder.co.uk >> _______________________________________________ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. > > > > -- > > Chris Albertson > Redondo Beach, California > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
