On 28 Mar, 2014, at 20:53 , Bob Camp <li...@rtty.us> wrote: > The problem is that it can / might / could / will create a “dc bias” in the > noise. When you filter it, you get a bump rather than zero. If your GPSDO has > a 47 ns wide sawtooth, that could be a pretty big bump. There’s no way to > know if the bridge is seconds, minutes, or hours wide. You can make a good > guess that hours are a *lot* less common than seconds….
Yes, and you can get long term "dc bias" not only in the "hanging bridge" case but, in diminishing amounts, when the sawtooth frequency passes through 1/2 Hz, 1/3 Hz, 1/4 Hz and so on, i.e. where the sawtooth period is an exact integer number of seconds. I think the 4th graph here http://www.leapsecond.com/pages/m12/sawtooth.htm shows a 1/2 Hz sawtooth with a non-zero mean error for an extended period. I guess, viewed this way, the 5th graph would be the 1/1 Hz sawtooth (which becomes 0 Hz when folded into the Nyquist bandwidth), which is the worst case but not the only case. Dennis Ferguson _______________________________________________ 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.