Does the GPS backup include other sats ? As long as all sites could see the same sat then using it as a standard they would drift together.
Stanley ----- Original Message ---- From: Ralph Smith <ra...@ralphsmith.org> To: Discussion of precise time and frequency measurement <time-nuts@febo.com> Sent: Thu, September 9, 2010 11:45:04 AM Subject: Re: [time-nuts] Timing Distribution in Mountainous Terrain The requirement is 30 nanoseconds, so individual rubidium holdover over six days won't cut it. Ralph On Thu, September 9, 2010 11:58 am, Robert Darlington wrote: > Symmetricom makes GPS based NTP time servers with excellent holdover > capability. I think our "SyncServer" with an OXCO is good for +/- 0.5 > second holdover over something like 60 days. They have options for Rb > oscillators installed that will make that much much better and it might > fall > inside of your requirements. Give them a look. You're welcome to mail me > directly with questions about mine if you like. > > -Bob > > On Thu, Sep 9, 2010 at 9:37 AM, Ralph Smith <ra...@ralphsmith.org> wrote: > >> 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 -- 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. > _______________________________________________ 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.
