[time-nuts] Re: 5071B cRB

[Tom Knox]

The Spectradynamic cRB not only has amazing specs, but is in my humble opinion is a piece of art when you look at build quality, overall engineering, not to mention performance. And although about twice the price of a 5071A I think once the cost of ownership is added it may prove more affordable in the long term.
I think this was a collaboration between, Spectradynamics, DARPA, NIST, and perhaps additional parties.
An interesting side note, Sepctradynamics was founded by Franklin Ascarrunz and Craig Nelson, And as many of you know Craig left SDI to work at NIST with the Phase Noise Measurement Group where his amazing contributions to the field speak for themself.
Cheers;
Tom Knox
SR Test and Measurement Engineer
Phoenix Research
4870 Meredith Way Apt 102
Boulder, Co 80303
Formerly of:
357 Fox Lane
Superior Co 80027
303-554-0307
actast at hotmail.com

https://www.thedenverchannel.com/news/marshall-fire/superior-man-moving-forward-after-losing-dream-research-lab-during-marshall-fire

"Peace is not the absence of violence, but the presence of Justice" Both MLK and Albert Einstein
________________________________
From: Attila Kinali via time-nuts <time-nuts at lists.febo.com>
Sent: Thursday, June 15, 2023 12:30 AM
To: Discussion of precise time and frequency measurement <time-nuts at lists.febo.com>
Cc: Attila Kinali <attila at kinali.ch>
Subject: [time-nuts] Re: 5071B

On Wed, 14 Jun 2023 09:30:20 -0500
Bob Camp via time-nuts <time-nuts at lists.febo.com> wrote:


> I suspect one of the reasons prices don’t get published is that some (but certainly not all)
> folks do indeed make a cost based decision between the two. The “which is best” debate
> goes back at least into the 1980’s. There are applications that either one just might do
> fine in.

While prices are not published, they aren't really secret either. If you ask at
conferences, you'll be told the price of any atomic clock you are interested in.
Even I, who is not buying any of these, have learned the prices of most of the
major used atomic clocks over the years.


> Some form of “super machine” that combined the long term stability of the 5071 with the
> short term stability of a maser (passive or maybe even active) *and* came in roughly
> the same in terms of  cost, size, proven performance (on production units), and tube life
> as the 5071, would be a game changer.

We already have that. The SpectraDynamics cRb-Clock cold Rubidium clock delivers
the short term stability of a passive hydrogen maser with a flicker frequency
floor 3e-15 and no drift. It costs a little bit more than a 5071, though, but
it's also a more complex machine with lower production volume.


On Thu, 15 Jun 2023 05:40:52 +0000
Poul-Henning Kamp via time-nuts <time-nuts at lists.febo.com> wrote:

> Bob Camp via time-nuts writes:
>
> > Some form of “super machine” that combined the long term stability of the 5071 with the
> > short term stability of a maser (passive or maybe even active) *and* came in roughly
> > the same in terms of  cost, size, proven performance (on production units), and tube life
> > as the 5071, would be a game changer.
>
> What about shock and vibration sensitivity ?
>
> I keep hearing about optical clocks which drop lock if a door is
> slammed somewhere in the building ?

The optical system is pretty sensitive to vibration, but we are talking about
stabilities beyond 1e-15. Even a AHM will exhibit problems if you slam a door
somewhere in the building hard enough that an optical clock would unlock.

That said, one of the problems of why optical atomic clocks are so sensitive
is, because they are prototypes built on a breadboard. There is a lot that
can be affected by vibrations. Especially the early models suffered a lot
from that. Today, it's much better and people know which parts need to be
specially handled to ensure that they don't unlock because of a door slaming.
But vibration and even noise is still a major factor of instability in optical
clocks.

                        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
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