[time-nuts] clocks for amateur radio and astronomy (was: World's most precise.... wall clock)

[Attila Kinali]

On Wed, 10 Mar 2021 06:39:46 -0800
"Charlie" <charlie at drhabekost.com> 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, 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 Ï„ between
about 1s and maybe 100s. Beyond a Ï„ 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.

If you need better than that, either at shorter or longer Ï„,
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