Hi The other point that could be made is:
In a contest situation, you have a lot of stations to net to. You really aren't worried about the stability over 48 hours. You really are concerned about drift since your last set of contacts. If it takes you an hour or less to get to your next site, that's a *much* looser requirement than the 48 hour number. It all depends on what you are doing.... Bob -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Jim Lux Sent: Monday, March 11, 2013 10:13 AM To: [email protected] Subject: Re: [time-nuts] time-nuts Digest, Vol 104, Issue 37 On 3/11/13 6:49 AM, James Peroulas wrote: >> >> Date: Sun, 10 Mar 2013 17:37:13 -0700 >> From: gary <[email protected]> >> To: [email protected] >> Subject: Re: [time-nuts] frequency reference for portable operation >> Message-ID: <[email protected]> >> Content-Type: text/plain; charset=ISO-8859-1; format=flowed >> >> I haven't researched this yet, but the SDR crowd is using GSM and LTE >> for tuning their sample clocks. >> >>> https://github.com/steve-m/kalibrate-rtl >>> https://github.com/Evrytania/LTE-Cell-Scanner >> >> >> I have no idea what kind of accuracy you can get from a tower. >> > > GSM and LTE (and WCDMA and TD-SCDMA for that matter) are spec'd for 50 PPB > accuracy. However, these networks are 'often' synchronized to an external > reference which would presumably be GPS. This would give better long term > accuracy, but the short term accuracy would depend on the actual > implementation of the basestation. > > JP > > P.S. I'm the author of LTE-Cell-Scanner. > There might also be a problem getting a decent signal at some of the locations (remote mountain tops for instance). For several years, we did JPL Amateur Radio Club Field Day up on top of Mt Gleason, and it was notorious for no cell coverage. (I suspect it's better today.. that was at least 6-7 years ago) But a battery powered OCXO seems to be a "good enough" and self contained as well. _______________________________________________ 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.
