30ns for six days? You will probably will have to install Cesiums or Hydrogen Masers, a good Rubidium can drift 1.1us per day. Even with GPS it is hard to achieve, try to find a GPSDO that specifies +/-30ns to UTC .... some specify 30ns RMS, i.e. being < 30ns in ~70% of the time.
Rob Kimberley -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Ralph Smith Sent: 09 September 2010 5:49 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Timing Distribution in Mountainous Terrain The network is spread over about 250-300 US miles. Ralph On Thu, September 9, 2010 12:01 pm, Didier Juges wrote: > How widely spread is your network? > > ------------------------ > Sent from my BlackBerry Wireless thingy while I do other things... > > -----Original Message----- > From: "Ralph Smith" <[email protected]> > Sender: [email protected] > Date: Thu, 9 Sep 2010 11:37:46 > To: <[email protected]> > Reply-To: Discussion of precise time and frequency measurement > <[email protected]> > Subject: [time-nuts] Timing Distribution in Mountainous Terrain > > We have a requirement for approximately ten radio sites to be > synchronized to within 30 ns of each other. Ordinarily you could throw > in an appropriate GPSDO and be done with it. However, we also have the > reqirement to be able to operate independent of GPS for up to six > days. If we were able to have each site within line of sight of > another, and could form a network including all sites, we could do > differential time measurement between the mutually visible sites and correct in that way. > Unfortunately, that is not the case. Absolute time accuracy is not > critical, but relative time accuracy is. Does anyone out there have > any ideas? > > Thanks, > Ralph > AB4RS > > _______________________________________________ > time-nuts mailing list -- [email protected] To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ > time-nuts mailing list -- [email protected] To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
