> On 1/21/11 2:26 PM, Robert E. Seastrom wrote: > > > > Michael Holstein <michael.holst...@csuohio.edu> writes: > > > >>> I'd be curious to see what effects (if any) those who use > >>> GPS-disciplined NTP references in Southeastern Georgia see from this > >>> experiment. > >> > >> Aren't CDMA BTS clocked off GPS? > >> > >> NTP isn't going to be the only "ripple". > > > > Sure, and there are GPS-steered Rb clocks in telco-land too as well as > > a ton of stuff I don't know about yet until everyone else here chimes > > in; it's just that NTP is highly visible to NANOGers. > > if your high quality stratum one time source isn't capable of > free-running for a little while then it's not really high quality... > > you can of course test this simply by disconnecting the antenna. if the > dilution of precision gets sufficiently high or the boise floor climbs > above the signal then it should fail the gps out of the mix. our > symerticoms have upgraded ocxo and backup geographically distant ntp > sources in the pool to account for localized gps failure... > > I'm way to cheap to spring for the rubidum upgrade, the ocxo holdover is > supposed to be 1ms a day.
The recomndation for a UTC timescales is to be within less than 1us of UTC at any given time. -P
