Hi Shouldn´t 5x10^-11 over 50C be 1x10^-12 / C? So with 2-4°C variation it is 2-4x10^-12.
What about pressure variations for the HP5065 and other Rb´s? My LPRO have about 7x10^-14/mBar (hPa) so with 15-20mbar change, that can happen quite quick, it is also in the ^-12 range. The tempco for my LPRO is 7x10^-13/°C and drift in the high ^-14 per day so my GPSDO controller mostly fights the temperature and pressure variations I think. I like having a GPS disciplined Rb as I haven´t had to adjust it during the last years. Of course a OCXO based GPSDO will also stay on frequency. For me the Rb have been good when I have tested GPS modules and GPSDO´s just out of curiosity. In hold mode it have been useful to get the ADEV out to say 10000 secs (low ^-13). Lars Från: Bob Camp<mailto:kb...@n1k.org> Skickat: den 14 mars 2016 02:01 Till: Discussion of precise time and frequency measurement<mailto:time-nuts@febo.com> Ämne: Re: [time-nuts] HP 5065A repair Hi Some math: 5x10^-11 over 50C You have 1x10^-13 / C If you have pretty good HVAC you get 2C cycles. On a typical home system, you get 2X that or more. Net is a bump at 2x10^-13 (or more). That assumes no hysteresis. (Hint: there always is hysteresis). That assumes you have no rate dependent effects. (… they almost always are present ..). If you are at 10X the data sheet level, the bump is more like 2x10^-12 (or more). Either one will likely show up on a good test plot. Can you take care of all this? Of course you can. Does modeling and correcting all this fall into the “quick and easy fix” category? Nope, not at all. The thread is about a request for a simple approach to an Rb setup. That sort of thing does not include fancy models and all sorts of corrections. Bob > On Mar 13, 2016, at 5:10 PM, Poul-Henning Kamp <p...@phk.freebsd.dk> wrote: > > -------- > In message <aabmqmgvvauqc...@smtpout04.dca.untd.com>, cdel...@juno.com writes: > >> As far a tempco goes, unless your lab swings tens of degrees will you >> really see it? > > Well, I do... > > My air-con is far from optimal, but it clearly makes a very obvious > bump in my AVAR plots. > > > -- > Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 > p...@freebsd.org | TCP/IP since RFC 956 > FreeBSD committer | BSD since 4.3-tahoe > Never attribute to malice what can adequately be explained by incompetence. > _______________________________________________ > 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. _______________________________________________ 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.
