Hello,
And about temperature, in this article
http://www.dtic.mil/dtic/tr/fulltext/u2/a495520.pdf there is an
interesting point, in the last page: Riley answer to the question "You
mentioned larger cells. Where there any other things done go get these
fantastic results?
Regards,
Javier
On 18/01/2017 13:12, Bob Camp wrote:
Hi
You would need to redesign the Rb to work in a vacuum. There is a lot involved
in doing that. They depend on the air inside the package to properly operate the
heating in the physics package. Different parts of the package are at different
temperatures. Without the air cooling the temperature offsets could not be
properly
maintained.
There are a *lot* of differences between the GPS Rb’s and the ones we buy on
eBay. The fact that they operate in pretty far down the list of significant
differences.
The most simple answer to “why” the Rb is better is that the design requirements
on the two standards were different, as were the design teams. Coming up with
an Rb with better short term stability is the way that all worked out. That
short
term stability is better than other large cell Rb designs, but not by a crazy
amount.
How much better it is depends a lot on which large cell Rb design you compare
to.
It also depends a bit on which specific unit you are looking at.
All that said, space benign is indeed a pretty quiet environment. It certainly
does
help a bit if you operate there. There is also data on the GPS Rb’s that show
them
doing quite well on the ground. So no, it’s not all space, but space does not
hurt
their performance.
Bob
On Jan 18, 2017, at 12:23 AM, Li Ang <379...@qq.com> wrote:
Hi
I am wondering if anyone tried to put a Rb unit into a vacuum container. And
how much the performance is improved? Someone told me that's why the Rb clocks
are more stable than Cs clocks on the GPS satellites.
LiAng
---Original---
From: "Bob Camp"<kb...@n1k.org>
Date: 2017/1/17 21:20:23
To: "Discussion of precise time and frequency measurement"<time-nuts@febo.com>;"Perry
Sandeen"<sandee...@yahoo.com>;
Subject: Re: [time-nuts] How to create a super Rb standard
Hi
Since the physics package in the small Rb’s is different than the stuff in the
large units,
you have some basic limits on what you can do to improve them. The main things
people
have done are to modify them to turn off the temperature compensation and
replace it
with some sort of precision controlled thermal enclosure. Pressure compensation
is a good
idea on any of these parts (large or small). How much your particular unit
benefits is a
“that depends” sort of thing.
Bob
On Jan 16, 2017, at 10:24 PM, Perry Sandeen via time-nuts <time-nuts@febo.com>
wrote:
List
It looks like their is as infinitely small chance of being able to get 5065.
So what can be done with the telco Rb's (mine are analog tuned) to wring the
best possible performance from them? Sooper Duper power supplies, Peltier (sp)
cooling modules?
Regards,
Perrier
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