HI If that is what you currently have for references, then you probably need a “lab standard” to drive things. Having one reference for all the gear makes things *much* easier. You don’t have to mess with a lot of “which one’s right today” sort of decisions.
That would make the GPSDO pretty much a slam dunk decision. You get both the reference and the calibration all in one box. Bob On Mar 2, 2014, at 2:56 PM, Bob Albert <[email protected]> wrote: > Nigel, > > Thank you for your comments. I see the situation a bit more clearly now, and > will do some searches on Trimble and GPSDO and so on. Right now I am > interested in seeing what my options are, and deciding which way to go. > > Yes this can become an obsession but I keep reminding myself that it's a > hobby and isn't stopping me from eating or sleeping or breathing. I do have > fun with it. Recently I bored a couple of visitors showing how my counter > and signal generator drifted during warmup but eventually settled within > about 10 ppb of one another, within about a half hour. (Both units have 24/7 > ovens.) The generator actually accounts for nearly all the drift. The > counter is a venerable HP 5245L with 500 MHz plugin. > > Bob > > > > > On Sunday, March 2, 2014 10:33 AM, Tom Miller <[email protected]> > wrote: > > > ----- Original Message ----- > From: "Hal Murray" <[email protected]> > To: "Bob Albert" <[email protected]>; "Discussion of precise time and > frequency measurement" <[email protected]> > Cc: <[email protected]> > Sent: Sunday, March 02, 2014 2:45 AM > Subject: Re: [time-nuts] Another "atomic" clock question > > > > [email protected] said: >> Okay you want numbers. Well, I think 10 ppb or thereabouts should do it. >> Somewhere there is a discontinuity in accuracy plotted against cost and I >> don't want to cross that barrier just yet. If I can get 1 ppb without a >> big >> increase in cost, I'll take that. > > How good is your crystal? > > Junk crystals are good thermometers. Ballpark is 1 ppm/degree-C > If you are running ntpd, turn on loopstats and measure the temperature... > http://www.megapathdsl.net/~hmurray/ntp/slope.gif > > I've been watching a 3 MHz ovenized crystal. It was something like 4 for > $25 > from ebay. It's a 2 in sq can, over an inch high. It's got a few ppb of > noise over minutes/hours and a few more ppb of drift/wander over > days/months. > It took several weeks to stabilize after power on. > > -- > > Is that 3 MHz OCXO one from Ridge? If so, I opened one up and was surprised > to find it did not have any foam insulation. > > Tom > > _______________________________________________ > 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. > _______________________________________________ > 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. _______________________________________________ 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.
