On Fri, Feb 26, 2016 at 05:56:59PM -0500, Bob Camp wrote: > Cell phones since they first came out have *never ever* been setup > to run on anything other than GPS. Retrofitting them to use something > else would take a decade or more. We didn’t “destroy the backup”, there > never was one. Pretty much all of our surplus gizmos are cell tower > surplus (like 99.99%).
Bob, It depends. We're used to thinking of those GPS and oscillator packages as the only timing for a cell site, but that was not the case until fairly recently. In many of those sites, there was also transport gear that would take line timing from a CO or other site upstream that typically had diverse reference clocks available. It might even have provided a backup BITS T1 as a frequency reference to cell equipment. Even without a local transport node, prior to the last few years (where things seem to be going Ethernet), most cellular equipment was still taking TDM handoffs, and could revert to taking line timing off its transport circuits, thereby indirectly getting it from practically anything upstream if its local reference failed. Certainly, the surplus device pool is all GPS, but that's because of the number of additional devices deployed, not necessarily representative of the full footprint of LORAN and other methods that used to be available as indirect backup references for the sites. Of course, that's not going to be an option going forwards. I, for one, welcome our new Ethernet overlords. --msa _______________________________________________ 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.