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 <tmiller11...@verizon.net> wrote: ----- Original Message ----- From: "Hal Murray" <hmur...@megapathdsl.net> To: "Bob Albert" <bob91...@yahoo.com>; "Discussion of precise time and frequency measurement" <time-nuts@febo.com> Cc: <hmur...@megapathdsl.net> Sent: Sunday, March 02, 2014 2:45 AM Subject: Re: [time-nuts] Another "atomic" clock question bob91...@yahoo.com 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 -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ 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.
