My own belief is that almost everything can be blamed on GPS, but then much if not most is my own fault for using an indoor antenna only about 6 or 7 feet above ground level.
Except when excessive lightning activity is around, I run a continuous setup comparing 10 MHz phase between a T'Bolt GPSDO and a Rb, showing I & Q waveforms on a very slow roll-mode 'scope display which shows the most recent 4 hours. It just sits there and runs, and I glance at it many times per day in passing. It gets very messy much of the time. A month-long recording could net you quite a bit of couch time :-) Dana On Sat, Mar 27, 2021 at 11:21 AM Ole Petter Rønningen <[email protected]> wrote: > Active HM, yes - nothing in the logs that corresponds, except a .5 degC > diurnal temperature change - which roughly coincides with the outdoor temp, > so no help there.. > > This was meant as a quick-and-dirty check, so a months is not in the cards > - but that second antenna/receiver is climbing on my list of priorities, in > imminent danger of surpassing «doing nothing on the couch»! :) > > > 27. mar. 2021 kl. 16:52 skrev Dana Whitlow <[email protected]>: > > > > Ole, > > > > If you can stand the suspense, a time error recording of a month or more > > duration > > would probably be pretty informative (and interesting for us to see). > > > > And when you speak of the maser, is that an active hydrogen maser? If > so, > > you're > > a lucky man (unless it's in the process of dying). But there should be > > scads of > > diagnostics being logged, which should be enough to enable making a > fairly > > good > > confidence check on it. > > > > Dana > > > > > >> On Sat, Mar 27, 2021 at 8:33 AM Ole Petter Rønningen < > [email protected]> > >> wrote: > >> > >> Hi, Dana > >> > >> Thats the peculiar thing - these last 48 hors theres been a pretty clear > >> 24 hour cycle, pointing to temperature as the culprit; but the > preceeding > >> 48 hours the phase shift did not follow a 24 hour period at all; the > >> wheather has been all over the place, so it is hard to say.. More data > >> needed! As always.. > >> > >> (of course, there is always a possibility that I’ve somehow bungled the > >> data, and the period has been 24 hours all along) > >> > >> This is why I am looking for ballpark figures for the two main suspects; > >> water and temperature. > >> > >> I guess I should bite the bullet and rig up a second receiver/antenna > so I > >> can take the maser out of the equation.. (and reseal the connectors > >> properly) > >> > >> > >>>> 27. mar. 2021 kl. 14:04 skrev Dana Whitlow <[email protected]>: > >>> > >>> Ole, > >>> > >>> You did not mention whether this timing anomaly is periodic or steadily > >>> growing. > >>> That information could be of considerable diagnostic significance. > >>> > >>> Dana > >>> > >>> > >>>> On Sat, Mar 27, 2021 at 6:08 AM Ole Petter Ronningen < > >> [email protected]> > >>>> wrote: > >>>> > >>>> Hi, All > >>>> > >>>> I am trying to chase down a 2-3-4 ns/day "anomaly" in a gpsdo I am > >> working > >>>> on - it could be temperature sensitivity in the antenna (cheap patch > >>>> jobbie), or I suspect my sealing of the outside connectors may not be > >>>> watertight. I just wanted to ask the list of anyone know of/has an > >> estimate > >>>> of how much the propagation delay on an N and/or SMA can reasonably be > >>>> expected to change in the presence of water? is 3 ns in the right > >> ballpark, > >>>> or would that effect be way bigger/smaller? > >>>> > >>>> Likewise, does anyone have reasonably accurate figures for how much > >>>> temperature could be expected to affect the delay of signals? 20 ps? > 20 > >> ns? > >>>> Looking for some rough figures so I can look in the right direction.. > >>>> > >>>> I've used the same gpsdo, cable and location with a high quality > antenna > >>>> without seeing these effects, so I am fairly certain it is the antenna > >> (or > >>>> my reference maser giving up the ghost..) > >>>> > >>>> Thanks! > >>>> Ole > >>>> _______________________________________________ > >>>> time-nuts mailing list -- [email protected] -- To unsubscribe > >> send > >>>> an email to [email protected] > >>>> To unsubscribe, go to and follow the instructions there. > >>>> > >>> _______________________________________________ > >>> time-nuts mailing list -- [email protected] -- To unsubscribe > >> send an email to [email protected] > >>> To unsubscribe, go to and follow the instructions there. > >> _______________________________________________ > >> time-nuts mailing list -- [email protected] -- To unsubscribe > send > >> an email to [email protected] > >> To unsubscribe, go to and follow the instructions there. > > _______________________________________________ > > time-nuts mailing list -- [email protected] -- To unsubscribe > send an email to [email protected] > > To unsubscribe, go to and follow the instructions there. > _______________________________________________ > time-nuts mailing list -- [email protected] -- To unsubscribe send > an email to [email protected] > To unsubscribe, go to and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] -- To unsubscribe send an email to [email protected] To unsubscribe, go to and follow the instructions there.
