Hi > On Mar 10, 2021, at 12:17 PM, Attila Kinali <[email protected]> wrote: > > On Wed, 10 Mar 2021 06:39:46 -0800 > "Charlie" <[email protected]> wrote: > >> My question is thus: It seems that procuring a more precise PPS/time output >> unit is quite a bit more costly than what I have; even more costly is a unit >> that has both more precise PPS/time output, > > The question is more whether it is good enough. How accurate > do you need your time? How precise does it need to be? > If the answer to both questions is smaller than 100ns,
I suspect that’s a typo. “larger than 100 ns” ( 1 us > 100 ns ….) would seem to be the correct way to look at it. > then you > are good with anything you can get your hands on, even the cheapest > GPS receiver. If you need better than that, you need to look > more closely and calculate each contributor to uncertainty, > both random and systematic and see where you can and want to > improve (or compromise). > > >> and a really stable 10 Mhz >> output ( I might add that I am a Ham, where 1 uhz error is detrimental). > > At what time scales you need that 1µHz stability? Is it for > a few seconds? Or over a few hours? How accurate does it have > to be? > And are you sure it is really 1µHz @ 10MHz? Because that's > a stability better than 1e-13. Which isn't something most people > just have in their lab. You need a an exceptionally good OCXO to > reach down there (an OCXO that costs you as much as a car) > and even those reach it only over a very limited τ between > about 1s and maybe 100s. Beyond a τ of 1000s you have the option > of using a HP5065, possibly with Corby's Super-HP6065 modifications. > Even GPS takes until somwhere like 100ks to reach down to 1e-13. Even crazier if you are talking about your transmit frequency at VHF :) :). Welcome to why Hz, uHz, etc normally are replaced with ppm, ppb, and the like … That’s been the case in every place I’v ever worked on this stuff. Bob > > If you need better than that, either at shorter or longer τ, > then we are clearly deep in atomic clock territory. Either > hydrogen maser. caesium beam standard or cold atomic clock. > > Attila Kinali > -- > The driving force behind research is the question: "Why?" > There are things we don't understand and things we always > wonder about. And that's why we do research. > -- Kobayashi Makoto > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
