On 7/16/2010 1:57 AM, Hal Murray wrote: > [email protected] said: > >> Most newer operational standards can't tolerate this and "accurate" time >> (better than a ms) is important. WiMAX requires TDD base stations to base >> station alignment to be better than 1 microsecond. Most telecom operators >> want to avoid GPS at every site. It's a logistical PITA. >> > Does that mean that the time has to match UTC or that all the clocks in the > system have to be screwed up by close to the same amount? > The spec is only relative, that is base station to base station not absolute. The only practical way to accomplish this is GPS, so as a practical matter it's GPS time.
There are a lot of problems with GPS in this application. Urban canyons, interference, logistics, indoor use, and politics are all issues. Oddly enough Iran, China, and even many European countries don't want critical infrastructure referenced to a US controlled system. Telecom systems are increasing moving indoors and this includes cellular. It would seem that bolting an antenna outside is no big deal, but often that is the dominant cost in a low cost application like femto base stations (those access point sized things that Verizon, AT&T, and others are selling.) -- mailto:[email protected] Oz POB 93167 Southlake, TX 76092 (Near DFW Airport) _______________________________________________ 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.
