Hi SDH/SONET generally is line timed rather than GPS locked. It's ultimate authority is the Stratum 1 above it... With CDMA framing, GPS time is actually the ultimate authority. With GSM (as with the CDMA carrier frequency) a free running oscillator is generally "good enough".
Bob On Mar 8, 2012, at 5:27 PM, Magnus Danielson <mag...@rubidium.dyndns.org> wrote: > On 03/08/2012 11:21 PM, Bob Camp wrote: >> Hi >> >> Should be *very* interesting to watch if they try to legislate something >> like that... > > Indeed. > > There are different telecom needs. CDMA isn't everything. > > SDH/SONET goes under G.811, meaning within 1E-11 in frequency. > GSM should be within +/- 50 ppb, but long-term should be like SDH/SONET. > etc. etc. > > Cheers, > Magnus > >> Bob >> >> -----Original Message----- >> From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On >> Behalf Of Poul-Henning Kamp >> Sent: Thursday, March 08, 2012 5:10 PM >> To: Discussion of precise time and frequency measurement >> Subject: Re: [time-nuts] Loran in the US >> >> In message<d20d95b53d5c40f5aca05df98fdb9...@vectron.com>, "Bob Camp" >> writes: >> >>> If they are backing up GPS for telcom, then CDMA timing is the most likely >>> target. That gets them to 10 us max and< 1 us typical. Of course somebody >>> would have to buy the gear to actually *use* it to do any good... (yes I >>> could and have gone on and on about that topic). >> >> Well, they do actually regulate telecoms, so they may simply be told that >> it will be a condition for their licenses. >> >> That happened with respect to power backups for cellular towers >> after Katrina showed the inadequacy of 3 hours lead-acid backup. >> > > > _______________________________________________ > 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.
