Re: [time-nuts] Time Dilation tinkering

[Bert Kehren via time-nuts]

Around 2000 when Offshore Navigation went Bell up because of GPS, I  
purchased more than 50 Cesium Standards most HP 5061A but also some FTS units.  
Most HP units went in a crate to Germany, kept a few, but kept all FTS units. 
I  did take one FTS on the plane from Miami to Frankfurt operating, 
fascinated by  what HP had done. This was before my time nuts days and had no 
way  
to  measure any thing, but it fit nicely in a carry on with wheels about 50 
lb, 20  lb 12V 18 A batteries, 20 lb FTS 5000. No problem at security, while 
waiting for  boarding had it plugged in the Admirals Club and on arrival 
plugged it in to the  12 V of the rental car.
Having a life long Platinum  5 Million Mile card and First Class may  have 
helped. Having twice in the last 30 years moved my lab to and from Germany  
I have carried some pretty heavy and large equipment on board with no  
problem ever.I still have the Samsonite suit cases that fit 19 inch  
instruments.
Bert Kehren
 
 
In a message dated 3/23/2017 12:00:34 P.M. Eastern Daylight Time,  
eb4...@gmail.com writes:

Not  mentioning that the clock traveled in a passenger seat (even with 
the seat  belt fastened). The vision of a big box with  cables and a good 
sized  clock ticking (it was a Patek Philippe movement in early HP 
Cesiums)  frightened some passengers  and the person accompanying the 
clock had  to give a lot of explanations. The use of the word "atomic" 
worsened  things somewhat.

(Memories from Apollo flights good  times)

Regards,

Ignacio, EB4APL



El 23/03/2017 a  las 12:33, Bob Camp escribió:
> Hi
>
> Back before GPS and  similar systems, hauling Cs standards on commercial 
aircraft was
> a bit  more common than it is today. One of the critical tricks of the 
trade was  knowing where
> each power outlet was on a specific plane and how close  it was to this 
or that seat. The next
> trick was knowing how to talk  the crew into letting you plug the gizmo 
in the seat next to yours
>  into that outlet. Sometimes the magic worked and other times you had to 
depend  on your
> battery pack. Needless to say, getting through the over ocean  travel 
process with a dead
> standard was not good news.
>
>  Bob
>
>> On Mar 22, 2017, at 10:59 PM, Bob Bownes  <bow...@gmail.com> wrote:
>>
>> It's not getting one  past the airport authorities that's the issue. 
It's getting one that's powered  up past them. ;)
>>
>> Written from about 10,000'.  :)
>>
>>> On Mar 22, 2017, at 20:15, Tom Van Baak  <t...@leapsecond.com> wrote:
>>>
>>> Chris  Albertson wrote:
>>>> Why drive up a mountain?
>>>  "Because it's there" ;-)  And because there's a paved road, and it's  
free, and there's a place to stay overnight, and the mountain doesn't move.  
Plus a car makes a good portable time lab; you can share the experience 
with  family or students or visiting time nuts; and a number of technical  
reasons.
>>>
>>> But most importantly: you can remain  at altitude as long as you want 
-- in order to accumulate just enough  nanoseconds of time dilation to meet 
your experiment's S/N goal -- without  running into (or much worse, going 
beyond) the flicker floor of your  clocks.
>>>
>>> There are several different ways to  measure time dilation with atomic 
clocks. Some notes here:
>>>  http://leapsecond.com/pages/atomic-tom/
>>>
>>>
>>>>  Take the clock with you inside the pressurized cabin of a commercial  
airliner
>>> Yes, and this has been done many times. The first  (1971) and most 
famous of all traveling clock relativity experiments  is:
>>>  https://en.wikipedia.org/wiki/Hafele%E2%80%93Keating_experiment
>>>
>>>  For vintage hp flying clock articles see:
>>>  https://www.febo.com/pipermail/time-nuts/2013-January/073743.html
>>>
>>>  Two modern examples are described here:
>>>
>>> "Time  flies"
>>>  http://www.npl.co.uk/news/time-flies
>>>
>>>  "Demonstrating Relativity by Flying Atomic Clocks"
>>>  http://www.npl.co.uk/upload/pdf/metromnia_issue18.pdf
>>>
>>>  /tvb
>>>
>>> - Original Message  -
>>> From: Chris Albertson
>>> To: Tom Van Baak ;  Discussion of precise time and frequency measurement
>>> Sent:  Tuesday, March 21, 2017 7:12 PM
>>> Subject: Re: [time-nuts] Time  Dilation tinkering
>>>
>>> "flight" there is the  word.Why drive up a mountain?   Take the 
clock with  you inside the pressurized cabin of a commercial airliner next time 
you are on  one of those 10 hour trans=pacific flights.   You be taller 
then any  mountain and it is actually cheaper then a weather  balloon.
>>>
>&g

Re: [time-nuts] Time Dilation tinkering

[MLewis]

Rather than commercial passenger flights, it used to be one could get 
connections and fly along on transport, ferry or private flights, 
typically for a (no-frills) low fee.


There are also flights made for testing equipment at altitude, including 
radio, satellite, imaging or other sensing equipment. Rather than hiring 
such, if it could be demonstrated that your experiment wouldn't 
interfere with their test/survey/experiment instruments, you may find 
someone sympathetic to letting you tag along. Local universities may 
know of sympathetic companies or pilots. Or check with local flying 
instructors or inspectors, who seem to know everything that's going on.
(A friend once had to accompany an imaging package on a Lear Jet. With 
three hours rented and his tests completed in one, he got to sit at the 
controls and buzz around the north until they had to return.)


The above would not only let you bring your powered experiment package 
along to altitude, but not create a panic when commercial passengers or 
cabin crew saw blinking lights or some such. And imagine if you're seen 
hooking up a cable to a device and collecting data into a laptop... And 
you could even be in trouble if seen doing anything with numbers that 
wasn't obviously accounting.


On 22/03/2017 10:59 PM, Bob Bownes wrote:

It's not getting one past the airport authorities that's the issue. It's 
getting one that's powered up past them. ;)

Written from about 10,000'. :)


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Re: [time-nuts] Time Dilation tinkering

[EB4APL]

Not mentioning that the clock traveled in a passenger seat (even with 
the seat belt fastened). The vision of a big box with  cables and a good 
sized clock ticking (it was a Patek Philippe movement in early HP 
Cesiums) frightened some passengers  and the person accompanying the 
clock had to give a lot of explanations. The use of the word "atomic" 
worsened things somewhat.


(Memories from Apollo flights good times)

Regards,

Ignacio, EB4APL



El 23/03/2017 a las 12:33, Bob Camp escribió:

Hi

Back before GPS and similar systems, hauling Cs standards on commercial 
aircraft was
a bit more common than it is today. One of the critical tricks of the trade was 
knowing where
each power outlet was on a specific plane and how close it was to this or that 
seat. The next
trick was knowing how to talk the crew into letting you plug the gizmo in the 
seat next to yours
into that outlet. Sometimes the magic worked and other times you had to depend 
on your
battery pack. Needless to say, getting through the over ocean travel process 
with a dead
standard was not good news.

Bob


On Mar 22, 2017, at 10:59 PM, Bob Bownes <bow...@gmail.com> wrote:

It's not getting one past the airport authorities that's the issue. It's 
getting one that's powered up past them. ;)

Written from about 10,000'. :)


On Mar 22, 2017, at 20:15, Tom Van Baak <t...@leapsecond.com> wrote:

Chris Albertson wrote:

Why drive up a mountain?

"Because it's there" ;-)  And because there's a paved road, and it's free, and 
there's a place to stay overnight, and the mountain doesn't move. Plus a car makes a good 
portable time lab; you can share the experience with family or students or visiting time 
nuts; and a number of technical reasons.

But most importantly: you can remain at altitude as long as you want -- in 
order to accumulate just enough nanoseconds of time dilation to meet your 
experiment's S/N goal -- without running into (or much worse, going beyond) the 
flicker floor of your clocks.

There are several different ways to measure time dilation with atomic clocks. 
Some notes here:
http://leapsecond.com/pages/atomic-tom/



Take the clock with you inside the pressurized cabin of a commercial airliner

Yes, and this has been done many times. The first (1971) and most famous of all 
traveling clock relativity experiments is:
https://en.wikipedia.org/wiki/Hafele%E2%80%93Keating_experiment

For vintage hp flying clock articles see:
https://www.febo.com/pipermail/time-nuts/2013-January/073743.html

Two modern examples are described here:

"Time flies"
http://www.npl.co.uk/news/time-flies

"Demonstrating Relativity by Flying Atomic Clocks"
http://www.npl.co.uk/upload/pdf/metromnia_issue18.pdf

/tvb

- Original Message -
From: Chris Albertson
To: Tom Van Baak ; Discussion of precise time and frequency measurement
Sent: Tuesday, March 21, 2017 7:12 PM
Subject: Re: [time-nuts] Time Dilation tinkering

"flight" there is the word.Why drive up a mountain?   Take the clock with 
you inside the pressurized cabin of a commercial airliner next time you are on one of 
those 10 hour trans=pacific flights.   You be taller then any mountain and it is actually 
cheaper then a weather balloon.

Can you get a Rb clock past the TSA x-ray machine.   Maybe if you ask first.  
There must be a way to hand cary specialized equipment.

On Tue, Mar 21, 2017 at 7:03 PM, Tom Van Baak <t...@leapsecond.com> wrote:

But attached is one of the first plots where I put a SA.32m in a home-brew 
vacuum chamber and pulled down to a few inches of Hg for a few hours to 
simulate the low pressure of a flight up to 50 or 90,000 ft. For a high 
altitude relativity experiment -- where you'd like your clock to remain stable 
to parts in e-13 and not accumulate too many stray ns -- it's not a good sign 
when your clock changes by 2e-11 (that's more than 1 ns per minute) just 
because of ambient pressure changes.


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Re: [time-nuts] Time Dilation tinkering

[Bob Camp]

Hi

Back before GPS and similar systems, hauling Cs standards on commercial 
aircraft was
a bit more common than it is today. One of the critical tricks of the trade was 
knowing where
each power outlet was on a specific plane and how close it was to this or that 
seat. The next
trick was knowing how to talk the crew into letting you plug the gizmo in the 
seat next to yours
into that outlet. Sometimes the magic worked and other times you had to depend 
on your 
battery pack. Needless to say, getting through the over ocean travel process 
with a dead
standard was not good news. 

Bob

> On Mar 22, 2017, at 10:59 PM, Bob Bownes <bow...@gmail.com> wrote:
> 
> It's not getting one past the airport authorities that's the issue. It's 
> getting one that's powered up past them. ;)
> 
> Written from about 10,000'. :)
> 
>> On Mar 22, 2017, at 20:15, Tom Van Baak <t...@leapsecond.com> wrote:
>> 
>> Chris Albertson wrote:
>>> Why drive up a mountain?
>> 
>> "Because it's there" ;-)  And because there's a paved road, and it's free, 
>> and there's a place to stay overnight, and the mountain doesn't move. Plus a 
>> car makes a good portable time lab; you can share the experience with family 
>> or students or visiting time nuts; and a number of technical reasons.
>> 
>> But most importantly: you can remain at altitude as long as you want -- in 
>> order to accumulate just enough nanoseconds of time dilation to meet your 
>> experiment's S/N goal -- without running into (or much worse, going beyond) 
>> the flicker floor of your clocks.
>> 
>> There are several different ways to measure time dilation with atomic 
>> clocks. Some notes here:
>> http://leapsecond.com/pages/atomic-tom/
>> 
>> 
>>> Take the clock with you inside the pressurized cabin of a commercial 
>>> airliner
>> 
>> Yes, and this has been done many times. The first (1971) and most famous of 
>> all traveling clock relativity experiments is:
>> https://en.wikipedia.org/wiki/Hafele%E2%80%93Keating_experiment
>> 
>> For vintage hp flying clock articles see:
>> https://www.febo.com/pipermail/time-nuts/2013-January/073743.html
>> 
>> Two modern examples are described here:
>> 
>> "Time flies"
>> http://www.npl.co.uk/news/time-flies
>> 
>> "Demonstrating Relativity by Flying Atomic Clocks"
>> http://www.npl.co.uk/upload/pdf/metromnia_issue18.pdf
>> 
>> /tvb
>> 
>> - Original Message - 
>> From: Chris Albertson 
>> To: Tom Van Baak ; Discussion of precise time and frequency measurement 
>> Sent: Tuesday, March 21, 2017 7:12 PM
>> Subject: Re: [time-nuts] Time Dilation tinkering
>> 
>> "flight" there is the word.Why drive up a mountain?   Take the clock 
>> with you inside the pressurized cabin of a commercial airliner next time you 
>> are on one of those 10 hour trans=pacific flights.   You be taller then any 
>> mountain and it is actually cheaper then a weather balloon. 
>> 
>> Can you get a Rb clock past the TSA x-ray machine.   Maybe if you ask first. 
>>  There must be a way to hand cary specialized equipment.
>> 
>> On Tue, Mar 21, 2017 at 7:03 PM, Tom Van Baak <t...@leapsecond.com> wrote:
>> 
>> But attached is one of the first plots where I put a SA.32m in a home-brew 
>> vacuum chamber and pulled down to a few inches of Hg for a few hours to 
>> simulate the low pressure of a flight up to 50 or 90,000 ft. For a high 
>> altitude relativity experiment -- where you'd like your clock to remain 
>> stable to parts in e-13 and not accumulate too many stray ns -- it's not a 
>> good sign when your clock changes by 2e-11 (that's more than 1 ns per 
>> minute) just because of ambient pressure changes.
>> 
>> 
>> ___
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Re: [time-nuts] Time Dilation tinkering

[Bob Bownes]

It's not getting one past the airport authorities that's the issue. It's 
getting one that's powered up past them. ;)

Written from about 10,000'. :)

> On Mar 22, 2017, at 20:15, Tom Van Baak <t...@leapsecond.com> wrote:
> 
> Chris Albertson wrote:
>> Why drive up a mountain?
> 
> "Because it's there" ;-)  And because there's a paved road, and it's free, 
> and there's a place to stay overnight, and the mountain doesn't move. Plus a 
> car makes a good portable time lab; you can share the experience with family 
> or students or visiting time nuts; and a number of technical reasons.
> 
> But most importantly: you can remain at altitude as long as you want -- in 
> order to accumulate just enough nanoseconds of time dilation to meet your 
> experiment's S/N goal -- without running into (or much worse, going beyond) 
> the flicker floor of your clocks.
> 
> There are several different ways to measure time dilation with atomic clocks. 
> Some notes here:
> http://leapsecond.com/pages/atomic-tom/
> 
> 
>> Take the clock with you inside the pressurized cabin of a commercial airliner
> 
> Yes, and this has been done many times. The first (1971) and most famous of 
> all traveling clock relativity experiments is:
> https://en.wikipedia.org/wiki/Hafele%E2%80%93Keating_experiment
> 
> For vintage hp flying clock articles see:
> https://www.febo.com/pipermail/time-nuts/2013-January/073743.html
> 
> Two modern examples are described here:
> 
> "Time flies"
> http://www.npl.co.uk/news/time-flies
> 
> "Demonstrating Relativity by Flying Atomic Clocks"
> http://www.npl.co.uk/upload/pdf/metromnia_issue18.pdf
> 
> /tvb
> 
> - Original Message - 
> From: Chris Albertson 
> To: Tom Van Baak ; Discussion of precise time and frequency measurement 
> Sent: Tuesday, March 21, 2017 7:12 PM
> Subject: Re: [time-nuts] Time Dilation tinkering
> 
> "flight" there is the word.Why drive up a mountain?   Take the clock with 
> you inside the pressurized cabin of a commercial airliner next time you are 
> on one of those 10 hour trans=pacific flights.   You be taller then any 
> mountain and it is actually cheaper then a weather balloon. 
> 
> Can you get a Rb clock past the TSA x-ray machine.   Maybe if you ask first.  
> There must be a way to hand cary specialized equipment.
> 
> On Tue, Mar 21, 2017 at 7:03 PM, Tom Van Baak <t...@leapsecond.com> wrote:
> 
> But attached is one of the first plots where I put a SA.32m in a home-brew 
> vacuum chamber and pulled down to a few inches of Hg for a few hours to 
> simulate the low pressure of a flight up to 50 or 90,000 ft. For a high 
> altitude relativity experiment -- where you'd like your clock to remain 
> stable to parts in e-13 and not accumulate too many stray ns -- it's not a 
> good sign when your clock changes by 2e-11 (that's more than 1 ns per minute) 
> just because of ambient pressure changes.
> 
> 
> ___
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Re: [time-nuts] Time Dilation tinkering

[MLewis]

On 22/03/2017 10:56 AM, jimlux wrote:

On 3/22/17 4:04 AM, Angus wrote:

No tall mountains in Australia, but...

Pikes Peak in the US is 14114 ft, 4304m and has a road to the top. Of 
course the base is at about 5000 ft/1600 m


In EU, there's probably a Seilbahn of some sort pretty high up in the 
Alps, although probably not to 4000m.




I've driven a few passes in Colorado above 10,000 and one above 12,000.
Four are above 12,000 ft, highest at 3,712 metres (12,183 ft).
https://en.wikipedia.org/wiki/List_of_mountain_passes_in_Colorado
Nine of those are higher than the top of the Eiger.

http://www.dangerousroads.org/rankings23/1610-highest-paved-road-list-in-usa.html

If it's the difference in height in a day, one option in Switzerland is 
the cog train to the Jungfraujoch. That's 3,466 metres (11,371 ft). The 
Jungfraubahn is listed as 3,454 metres (11,332 ft). It's not cheap; with 
my ski pass, I never went beyond the Eigergletscher.
You could start from Grindelwald at 1,034 m (3,392 ft) or from 
Lauterbrunnen at 802 m (2,631 ft).
You can drive to either from Interlaken, and there used to be a train, 
so you could start from 566 m (1,857 ft).


Michael
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Re: [time-nuts] Time Dilation tinkering

[Tom Van Baak]

Chris Albertson wrote:
> Why drive up a mountain?

"Because it's there" ;-)  And because there's a paved road, and it's free, and 
there's a place to stay overnight, and the mountain doesn't move. Plus a car 
makes a good portable time lab; you can share the experience with family or 
students or visiting time nuts; and a number of technical reasons.

But most importantly: you can remain at altitude as long as you want -- in 
order to accumulate just enough nanoseconds of time dilation to meet your 
experiment's S/N goal -- without running into (or much worse, going beyond) the 
flicker floor of your clocks.

There are several different ways to measure time dilation with atomic clocks. 
Some notes here:
http://leapsecond.com/pages/atomic-tom/


> Take the clock with you inside the pressurized cabin of a commercial airliner

Yes, and this has been done many times. The first (1971) and most famous of all 
traveling clock relativity experiments is:
https://en.wikipedia.org/wiki/Hafele%E2%80%93Keating_experiment

For vintage hp flying clock articles see:
https://www.febo.com/pipermail/time-nuts/2013-January/073743.html

Two modern examples are described here:

"Time flies"
http://www.npl.co.uk/news/time-flies

"Demonstrating Relativity by Flying Atomic Clocks"
http://www.npl.co.uk/upload/pdf/metromnia_issue18.pdf

/tvb

- Original Message - 
From: Chris Albertson 
To: Tom Van Baak ; Discussion of precise time and frequency measurement 
Sent: Tuesday, March 21, 2017 7:12 PM
Subject: Re: [time-nuts] Time Dilation tinkering

"flight" there is the word.Why drive up a mountain?   Take the clock with 
you inside the pressurized cabin of a commercial airliner next time you are on 
one of those 10 hour trans=pacific flights.   You be taller then any mountain 
and it is actually cheaper then a weather balloon. 

Can you get a Rb clock past the TSA x-ray machine.   Maybe if you ask first.  
There must be a way to hand cary specialized equipment.

On Tue, Mar 21, 2017 at 7:03 PM, Tom Van Baak <t...@leapsecond.com> wrote:

But attached is one of the first plots where I put a SA.32m in a home-brew 
vacuum chamber and pulled down to a few inches of Hg for a few hours to 
simulate the low pressure of a flight up to 50 or 90,000 ft. For a high 
altitude relativity experiment -- where you'd like your clock to remain stable 
to parts in e-13 and not accumulate too many stray ns -- it's not a good sign 
when your clock changes by 2e-11 (that's more than 1 ns per minute) just 
because of ambient pressure changes.


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Re: [time-nuts] Time Dilation tinkering

[Trent Piepho]

On Wed, Mar 22, 2017 at 9:39 AM, David C. Partridge
 wrote:
> Aiguille du Midi is 3842m IIRC (cable car base station at about 1000m).
>
> Dave
>
>
> Pikes Peak in the US is 14114 ft, 4304m and has a road to the top. Of course 
> the base is at about 5000 ft/1600 m
>
> In EU, there's probably a Seilbahn of some sort pretty high up in the Alps, 
> although probably not to 4000m.

Mauna Kea in Hawaii lets one drive from sea level to 13,796 ft, 4204
m.  Pretty big delta for a few hours of over land travel.
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Re: [time-nuts] Time Dilation tinkering

[Magnus Danielson]

Hi,

On 03/22/2017 05:55 PM, Attila Kinali wrote:

On Wed, 22 Mar 2017 07:56:45 -0700
jimlux  wrote:


In EU, there's probably a Seilbahn of some sort pretty high up in the
Alps, although probably not to 4000m.


But almost: https://en.wikipedia.org/wiki/Klein_Matterhorn
You could start in Sion(500m) or Visp(660m) take the train to Zermatt(1600m)
and from there the cablecar up to Klein Matterhorn(3880m). That would
give a nice 3000m of height difference. From Sion it takes 2.5h to 3h,
from Visp 2h to 2.5h. So you could potentially get up in the morning,
go up, install everything and be back for dinner :-)

If anyone wants to do that, please let me know. :-)


We both where uhm. kind of "volunteered" for a similar mission.
I would not mind a little "vacation" like that.

Cheers,
Magnus
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Re: [time-nuts] Time Dilation tinkering

[Bob kb8tq]

Hi

The outer can is at best only “sort of” sealed. 

Bob
> On Mar 22, 2017, at 10:58 AM, jimlux  wrote:
> 
> On 3/22/17 4:28 AM, Bob Camp wrote:
>> Hi
>> 
>> In this case, the vacuum might work against you. You change the pressure 
>> outside
>> the package and you get a flex. Flex translates to dimensional changes. That 
>> gives you
>> a frequency shift. People make absolute pressure sensors this way :) Rb’s 
>> are by no
>> means the only frequency standard impacted by this effect. Precision OCXO’s 
>> have the
>> same issue.
>> 
>> If you had enough room inside the package, you could do a “can in a can” 
>> sort of approach.
>> The outer vacuum sealed can flexes. The inner vacuum sealed can does not see 
>> anything.
>> You don’t eliminate the sensitivity this way, you do attenuate it quite a 
>> bit with each layer.
>> The question then becomes - is is worth the increase in size? Since the 
>> pressure sensitivity
>> is well below many other environmental factors …. probably not.
>> 
> 
> The CSAC is a can within a can (or more properly, the physics package is 
> inside a sealed can) but I don't know if there's vacuum inside the can.
> 
> 
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Re: [time-nuts] Time Dilation tinkering

[Majdi S. Abbas]

On Wed, Mar 22, 2017 at 07:52:38AM -0700, jimlux wrote:
> I imagine there's a "de minimis" quantity.  We didn't declare the cesium in
> the CSAC that we hand carried, and I'm pretty sure people have hand carried
> SRS Rb sources.

The letter they have covers anything up to a gram of Rb.
Certainly I'm not worried about it, I hand carry all sorts of things on
planes.

> off of the MSDS from Symmetricom/Microsemi
> 
> "All Symmetricom’s rubidium product can be shipped both domestically and
> internationally as a non-hazardous product. Symmetricom has received letters
> of interpretation from both the United States Department of Transportation
> (US DOT)Ref. No. 08-0154 and the International Air Transport
> Association(IATA) stating that Symmetricom’s rubidium product are not
> considered a hazardous Class 4 material in transportation.

2008 letter and response here:


https://www.phmsa.dot.gov/staticfiles/PHMSA/DownloadableFiles/Files/Interpretation%20Files/2008/080154.pdf

--msa
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Re: [time-nuts] Time Dilation tinkering

[Richard (Rick) Karlquist]

On 3/21/2017 7:12 PM, Chris Albertson wrote:

"flight" there is the word.Why drive up a mountain?   Take the clock
with you inside the pressurized cabin of a commercial airliner next time
you are on one of those 10 hour trans=pacific flights.   You be taller then
any mountain and it is actually cheaper then a weather balloon.


Yes Len Cutler did that 50 years ago, but the velocity of the plane also
has relativistic effects, so it's not a pure play.

Rick
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Re: [time-nuts] Time Dilation tinkering

[jimlux]

On 3/22/17 10:07 AM, Arnold Tibus wrote:



No tall mountains in Australia, but...

Pikes Peak in the US is 14114 ft, 4304m and has a road to the top. Of
course the base is at about 5000 ft/1600 m

In EU, there's probably a Seilbahn of some sort pretty high up in the
Alps, although probably not to 4000m.


I like the englisch word 'Seilbahn' ;-)
Well, the equipment is all made by German speaking companies, even in 
the US, so it seems an appropriate term.  Cable Car or Gondola aren't a 
unique description (i.e. Cable Cars in San Francisco and Gondolas in Venice)




Yes, not fully up to 4000 m, but there are in fact quite close to the
possibilities I know:

1. Klein Matterhorn, Walliser Alpen, Schweiz
Bergstation: 3820 m,

2. Aiguille du Midi, France
Télépherique de l’Aiguille du Midi
from Chamonix
Bergstation: 3777 m
Gourmet-Restaurant, 3842 m



Now that I think about it, though, speed of transit isn't as important 
as "length of time at altitude", because if we're following tvb's GREAT 
experiment, you have some clocks you leave at the low elevation, then 
some clocks you take high for while, then bring back low, and you 
compare the apparent "elapsed time". So longer duration helps increase 
the delta (but also, of course, adding to the variance of the two 
measurements, so there's a tradeoff).


So, are you better off with a week long camping trip at a moderate 
altitude, or a 14 hour flight at 10-15,000 meters.  Or would you take a 
small battery powered package up to the Bergstation and leave it there 
for a week?


The airport in La Paz, Bolivia is at around 4000 meters, the city itself 
at 3600m.



With relatively inexpensive atomic clocks, could one, with clever 
mailing addresses, send two clocks the opposite directions around the 
earth, and duplicate the famous traveling clocks experiment.  For 
instance, with a collaborator in Australia or India, EU, and US, you 
could probably arrange for the packages to go the "correct" direction.


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Re: [time-nuts] Time Dilation tinkering

[Magnus Danielson]

Hi,

On 03/22/2017 12:02 AM, Tom Van Baak wrote:

Scott McGrath wrote:

Or perhaps use the Symmetricom CSAC ...


Chris Albertson wrote:

Get a weather balloon.  Or there might already be an amateur group that
launches these.  Balloons can go much higher than your local mountains.


You'll both be interested to hear that CSAC+balloon was proposed for the "Genius by 
Stephen Hawking" TV program and, yes, we were in touch with amateur high altitude 
balloon groups. The producer rightly thought that a small atomic clock going up in a 
helium balloon would make dramatic video for a time dilation demonstration. Symmetricom / 
Microsemi donated a SA.* series clock to the effort.

I got involved on the science and engineering side of the equation. Spent a month 
trying to make it work and in the end the balloon idea was dropped. Just too hard, 
and too uncertain, and would require many more months of R, and finger 
crossing. So that's why, instead, I drove six calibrated 5071A down to Tucson for a 
conventional mountain-valley time dilation experiment -- which I knew from prior 
experience would work, especially with 3x redundancy. 
http://leapsecond.com/great2016a/

Note that miniature Rb and Cs clocks (such as those sold by Microsemi) are very 
small, ultra light, and amazingly low power -- but their long-term stability 
(including environmental effects) is a hundred or even a thousand times worse 
than a 5071A/001. This is not to say CSAC are poor clocks. In fact they have a 
superb mass/power/size to adev ratio, and thus there are many unique 
applications for them. But they are not designed to be laboratory-quality 
frequency standards


Indeed. CSAC is a superb clock for the power it consumes, and that is 
the market segment it attempts to address. For the same size and more 
power, you get much better stability. Just because it has Cesium doesn't 
make it a laboratory clock, it's a small gas-cell, with all the issues 
of one.


Which reminds me, I got three CSACs to measure. Into the lab I go.

Cheers,
Magnus
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Re: [time-nuts] Time Dilation tinkering

[Arnold Tibus]

Am 22.03.2017 um 15:56 schrieb jimlux:
> On 3/22/17 4:04 AM, Angus wrote:
>> On Tue, 21 Mar 2017 13:08:56 +0100, you wrote:
>>
>>> On Tue, 21 Mar 2017 13:38:51 +1100
>>> Hugh Blemings  wrote:
>>>
 This got me to wondering if a Rubidium based standard might do the
 trick
 - the Efratom SLCR-101s seem readily available for ~USD$200 mark.
>>>
>>> As TvB wrote, a single one will not do the trick. You will need
>>> a stability 1e-14 @1d. IIRC most Rb standards floor out at 1e-12 to
>>> 1e-13
>>> somewhere between 1k and 100k seconds. Even the Super-5065 has a floor
>>> of about 3-4e-14 (unless our friends here improved on this already).
>>>
>>> There will be a few things that you will need to do, if you want to go
>>> with Rubidiums:
>>> 1) Stabilize or compensate for environmental effects (temperature,
>>> air pressure)
>>> 2) Build ensembles of Rb clocks.
>>>
>>
>> Hi,
>>
>> Looking back at an old plot I did of a temperature controlled and air
>> pressure compensated LPRO against an M12+T, the Hadamard Deviation of
>> the 1000s averages of the 1PPS measurement was about 5E-14 at 1 day.
>> A large part of that was likely the GPS, so with a better rubidium
>> like an FRK-H in a sealed and temperature controlled enclosure you
>> might be around 1E-14 at 1 day.
>>
>> The bit that I'm not so sure about is the travelling. A long period of
>> movement, vibration, magnetic  fields, etc. all adding in could
>> obscure the effects of time dilation.
>>
>> It might be quite possible, although a nearby mountain and a friend
>> with a helicopter would make it a lot easier!
>>
>
> No tall mountains in Australia, but...
>
> Pikes Peak in the US is 14114 ft, 4304m and has a road to the top. Of
> course the base is at about 5000 ft/1600 m
>
> In EU, there's probably a Seilbahn of some sort pretty high up in the
> Alps, although probably not to 4000m.

I like the englisch word 'Seilbahn' ;-)

Yes, not fully up to 4000 m, but there are in fact quite close to the
possibilities I know:

1. Klein Matterhorn, Walliser Alpen, Schweiz
Bergstation: 3820 m,

2. Aiguille du Midi, France
Télépherique de l’Aiguille du Midi
from Chamonix
Bergstation: 3777 m
Gourmet-Restaurant, 3842 m

Enjoy, good luck!

Arnold
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Re: [time-nuts] Time Dilation tinkering

[David C. Partridge]

Aiguille du Midi is 3842m IIRC (cable car base station at about 1000m).

Dave

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of jimlux
Sent: 22 March 2017 14:57
To: time-nuts@febo.com
Subject: Re: [time-nuts] Time Dilation tinkering

On 3/22/17 4:04 AM, Angus wrote:
> On Tue, 21 Mar 2017 13:08:56 +0100, you wrote:
>
>> On Tue, 21 Mar 2017 13:38:51 +1100
>> Hugh Blemings <h...@blemings.org> wrote:
>>
>>> This got me to wondering if a Rubidium based standard might do the 
>>> trick
>>> - the Efratom SLCR-101s seem readily available for ~USD$200 mark.
>>
>> As TvB wrote, a single one will not do the trick. You will need a 
>> stability 1e-14 @1d. IIRC most Rb standards floor out at 1e-12 to 
>> 1e-13 somewhere between 1k and 100k seconds. Even the Super-5065 has 
>> a floor of about 3-4e-14 (unless our friends here improved on this already).
>>
>> There will be a few things that you will need to do, if you want to 
>> go with Rubidiums:
>> 1) Stabilize or compensate for environmental effects (temperature, 
>> air pressure)
>> 2) Build ensembles of Rb clocks.
>>
>
> Hi,
>
> Looking back at an old plot I did of a temperature controlled and air 
> pressure compensated LPRO against an M12+T, the Hadamard Deviation of 
> the 1000s averages of the 1PPS measurement was about 5E-14 at 1 day.
> A large part of that was likely the GPS, so with a better rubidium 
> like an FRK-H in a sealed and temperature controlled enclosure you 
> might be around 1E-14 at 1 day.
>
> The bit that I'm not so sure about is the travelling. A long period of 
> movement, vibration, magnetic  fields, etc. all adding in could 
> obscure the effects of time dilation.
>
> It might be quite possible, although a nearby mountain and a friend 
> with a helicopter would make it a lot easier!
>

No tall mountains in Australia, but...

Pikes Peak in the US is 14114 ft, 4304m and has a road to the top. Of course 
the base is at about 5000 ft/1600 m

In EU, there's probably a Seilbahn of some sort pretty high up in the Alps, 
although probably not to 4000m.



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Re: [time-nuts] Time Dilation tinkering

[Attila Kinali]

On Wed, 22 Mar 2017 07:56:45 -0700
jimlux  wrote:

> In EU, there's probably a Seilbahn of some sort pretty high up in the 
> Alps, although probably not to 4000m.

But almost: https://en.wikipedia.org/wiki/Klein_Matterhorn
You could start in Sion(500m) or Visp(660m) take the train to Zermatt(1600m)
and from there the cablecar up to Klein Matterhorn(3880m). That would
give a nice 3000m of height difference. From Sion it takes 2.5h to 3h,
from Visp 2h to 2.5h. So you could potentially get up in the morning,
go up, install everything and be back for dinner :-)

If anyone wants to do that, please let me know. :-)

Attila Kinali
-- 
It is upon moral qualities that a society is ultimately founded. All 
the prosperity and technological sophistication in the world is of no 
use without that foundation.
 -- Miss Matheson, The Diamond Age, Neil Stephenson
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Re: [time-nuts] Time Dilation tinkering

[jimlux]

On 3/22/17 4:28 AM, Bob Camp wrote:

Hi

In this case, the vacuum might work against you. You change the pressure outside
the package and you get a flex. Flex translates to dimensional changes. That 
gives you
a frequency shift. People make absolute pressure sensors this way :) Rb’s are 
by no
means the only frequency standard impacted by this effect. Precision OCXO’s 
have the
same issue.

If you had enough room inside the package, you could do a “can in a can” sort 
of approach.
The outer vacuum sealed can flexes. The inner vacuum sealed can does not see 
anything.
You don’t eliminate the sensitivity this way, you do attenuate it quite a bit 
with each layer.
The question then becomes - is is worth the increase in size? Since the 
pressure sensitivity
is well below many other environmental factors …. probably not.



The CSAC is a can within a can (or more properly, the physics package is 
inside a sealed can) but I don't know if there's vacuum inside the can.



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Re: [time-nuts] Time Dilation tinkering

[jimlux]

On 3/22/17 12:04 AM, Michael Wouters wrote:

Dear Chris,

I believe IATA prohibits the carriage of any quantity of rubidium on
passenger aircraft.
You have to complete a "Dangerous Goods Declaration" and it then has
to go by cargo aircraft.



I imagine there's a "de minimis" quantity.  We didn't declare the cesium 
in the CSAC that we hand carried, and I'm pretty sure people have hand 
carried SRS Rb sources.


off of the MSDS from Symmetricom/Microsemi

"All Symmetricom’s rubidium product can be shipped both domestically and 
internationally as a non-hazardous product. Symmetricom has received 
letters of interpretation from both the United States Department of 
Transportation (US DOT)Ref. No. 08-0154 and the International Air 
Transport Association(IATA) stating that Symmetricom’s rubidium product 
are not considered a hazardous Class 4 material in transportation.




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Re: [time-nuts] Time Dilation tinkering

[William H. Fite]

Unhappily, local TSA authorities have--or at least appropriate to
themselves--the prerogative to disregard prior approvals from their
superiors. A former colleague of mine used to hand carry an ultra-high
precision gas dilutor between research sites. She had written approvals
from TSA in DC that included written specifications and interior/exterior
photographs of the electromechanical device. She never had any issues until
one occasion in Wilmington, NC, when a supervisor glanced contemptuously at
her documents and then opened (and irreparably damaged) the measurement
cell to the tune of ~$20K in repairs. A formal complaint to TSA generated a
pro forma letter of apology with a polite refusal to pay the repair cost.

A similar incident occurred some months later in Sacramento. On that
occasion, she literally threw her 60 year old, 97 pound, silver-haired body
across the device, saying that they could arrest her but they would not
destroy another instrument. Airport police were summoned, one of whom had a
lick of sense. He and an indignant TSA 3-striper went off to the phone,
taking her documents, university ID, and passport, the police lieutenant
first telling his officers to prevent the TSA people from touching the
instrument. Half an hour later, they were back, accompanied by a TSA suit
who apologized profusely and personally accompanied her to her gate.

Herman Wouk once described the Navy as a master plan designed by geniuses
for execution by idiots. The TSA seems to have been created in the same
factory.



On Wednesday, March 22, 2017, jimlux  wrote:

> On 3/21/17 7:12 PM, Chris Albertson wrote:
>
>> "flight" there is the word.Why drive up a mountain?   Take the clock
>> with you inside the pressurized cabin of a commercial airliner next time
>> you are on one of those 10 hour trans=pacific flights.   You be taller
>> then
>> any mountain and it is actually cheaper then a weather balloon.
>>
>> Can you get a Rb clock past the TSA x-ray machine.   Maybe if you ask
>> first.  There must be a way to hand cary specialized equipment.
>>
>>
>>
> I hand carry specialized equipment all the time and let it go through the
> x-ray.   About 1 time out of 10, they'll ask to open it up so they can swab
> it for the explosives residue ion mobility machine. Nothing looks as
> suspicious as a big block of something with two wires come out of it (i.e.
> a 7Amp-hour 12V lead acid battery).
>
> In fact, I did it yesterday with an unlabeled black pelican case holding a
> 8x10" PC board with a bunch of cards stacked on it.
>
>
> While I have my NASA ID and a shipping document describing it, I've never
> had to show either. Driver's license, 55 year old guy who looks like an
> engineer, and so forth, so maybe I don't look like the notional threat?
>
>
> When we hand carry "flight hardware" we do put it in a QA sealed (tape)
> antistatic bag, in a QA sealed container, with a special letter that's been
> coordinated 24 hours before with TSA. And we don't let it go through the
> X-ray (although not for any good reason that I know..). There's some
> process you're supposed to follow if they insist on opening it so you show
> up at the airport hours ahead of time.
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-- 
William H Fite, PhD
Independent Consultant
Statistical Analysis & Research Methods
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Re: [time-nuts] Time Dilation tinkering

[Bert Kehren via time-nuts]

I remember a time when some at PBT referred to the HP5065A as their  
precision pressure sensor
Bert Kehren
 
In a message dated 3/22/2017 10:03:58 A.M. Eastern Daylight Time,  
kb...@n1k.org writes:

Hi

In this case, the vacuum might work against you. You  change the pressure 
outside
the package and you get a flex. Flex translates  to dimensional changes. 
That gives you
a frequency shift. People make  absolute pressure sensors this way :) Rb’s 
are by no 
means the only  frequency standard impacted by this effect. Precision OCXO’
s have the
same  issue.

If you had enough room inside the package, you could do a “can  in a can” 
sort of approach. 
The outer vacuum sealed can flexes. The inner  vacuum sealed can does not 
see anything. 
You don’t eliminate the  sensitivity this way, you do attenuate it quite a 
bit with each layer. 
The  question then becomes - is is worth the increase in size? Since the 
pressure  sensitivity 
is well below many other environmental factors …. probably  not.

Bob

> On Mar 22, 2017, at 1:04 AM, jimlux   wrote:
> 
> On 3/21/17 4:29 PM, Hal  Murray wrote:
>> 
>> scmcgr...@gmail.com  said:
>>> However CSAC not subject to barometric effects as Rb  units are
>> 
>> Does anybody tried to measure CSAC vs  pressure?
>> 
>> 
>> 
> The physics package  in a CSAC is a vacuum, so it probably won't make 
much difference.
>  
> But, as a practical matter, I have a system with a CSAC going through  
thermal vacuum testing as I write this. We'll get some test data and we can  
compare the frequency against GPS and a OCXO at room temp/pressure, and at  
various temps in vacuum.
> 
> Remind me in 2 weeks, and I should  have the data plotted.
> 
> 
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Re: [time-nuts] Time Dilation tinkering

[jimlux]

On 3/22/17 4:04 AM, Angus wrote:

On Tue, 21 Mar 2017 13:08:56 +0100, you wrote:


On Tue, 21 Mar 2017 13:38:51 +1100
Hugh Blemings  wrote:


This got me to wondering if a Rubidium based standard might do the trick
- the Efratom SLCR-101s seem readily available for ~USD$200 mark.


As TvB wrote, a single one will not do the trick. You will need
a stability 1e-14 @1d. IIRC most Rb standards floor out at 1e-12 to 1e-13
somewhere between 1k and 100k seconds. Even the Super-5065 has a floor
of about 3-4e-14 (unless our friends here improved on this already).

There will be a few things that you will need to do, if you want to go
with Rubidiums:
1) Stabilize or compensate for environmental effects (temperature, air pressure)
2) Build ensembles of Rb clocks.



Hi,

Looking back at an old plot I did of a temperature controlled and air
pressure compensated LPRO against an M12+T, the Hadamard Deviation of
the 1000s averages of the 1PPS measurement was about 5E-14 at 1 day.
A large part of that was likely the GPS, so with a better rubidium
like an FRK-H in a sealed and temperature controlled enclosure you
might be around 1E-14 at 1 day.

The bit that I'm not so sure about is the travelling. A long period of
movement, vibration, magnetic  fields, etc. all adding in could
obscure the effects of time dilation.

It might be quite possible, although a nearby mountain and a friend
with a helicopter would make it a lot easier!



No tall mountains in Australia, but...

Pikes Peak in the US is 14114 ft, 4304m and has a road to the top. Of 
course the base is at about 5000 ft/1600 m


In EU, there's probably a Seilbahn of some sort pretty high up in the 
Alps, although probably not to 4000m.




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Re: [time-nuts] Time Dilation tinkering

[jimlux]

On 3/21/17 10:36 PM, Michael Wouters wrote:

Yes, that's what I was quoted by the Microsemi agent and the price on
Mouser is similar.
The $1568 version was EOL'ed in December 2016; the more expensive unit is
the '2nd generation'.


Ah probably the one that has a good seal and has a rated temperature 
wider than 0-35C.



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Re: [time-nuts] Time Dilation tinkering

[Scott McGrath]

Ive been playing with one for work for the past few weeks and the Nor Easter 
which blew through NE did not affect short term ADEV with Tau < 1000s and that 
had a signficant drop in local barometric pressure for several hours

As to long term controlled studies no have not had opportunity to do so yet so 
that was an off the cuff observation based on the storm and not scientific data.

I'd be interested in any other observations around the same time though if 
anyone else is running a CSAC in NE


> On Mar 21, 2017, at 8:25 PM, Bob Camp  wrote:
> 
> Hi
> 
> Ummm … e …. it’s a gas cell standard. I’d bet there is a pressure effect.
> 
> Bob
> 
>> On Mar 21, 2017, at 7:01 PM, Scott McGrath  wrote:
>> 
>> Noted
>> 
>> However CSAC not subject to barometric effects as Rb units are
>> 
>> Content by Scott
>> Typos by Siri
>> 
 On Mar 21, 2017, at 4:18 PM, jimlux  wrote:
 
 On 3/21/17 12:51 PM, Scott McGrath wrote:
 Or perhaps use the Symmetricom CSAC ...
 
 Relatively expensive but might work
 
>>> 
>>> 
>>> The CSAC  is 8E-12 AVAR at 1000 seconds, comparable to a Rb.
>>> 
>>> 
>>> See also http://tycho.usno.navy.mil/ptti/2011papers/Paper27.pdf
>>> which shows a bit better performance (3E-12 @ 1000s), but the best 
>>> performance appears to be at 10,000 seconds.
>>> 
>>> 
>>> but don't you need better?
>>> Attila wrote> You will need a stability 1e-14 @1d.
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Re: [time-nuts] Time Dilation tinkering

[Angus]

On Tue, 21 Mar 2017 13:08:56 +0100, you wrote:

>On Tue, 21 Mar 2017 13:38:51 +1100
>Hugh Blemings  wrote:
>
>> This got me to wondering if a Rubidium based standard might do the trick 
>> - the Efratom SLCR-101s seem readily available for ~USD$200 mark.
>
>As TvB wrote, a single one will not do the trick. You will need 
>a stability 1e-14 @1d. IIRC most Rb standards floor out at 1e-12 to 1e-13
>somewhere between 1k and 100k seconds. Even the Super-5065 has a floor
>of about 3-4e-14 (unless our friends here improved on this already).
>
>There will be a few things that you will need to do, if you want to go
>with Rubidiums:
>1) Stabilize or compensate for environmental effects (temperature, air 
>pressure)
>2) Build ensembles of Rb clocks.
>

Hi,

Looking back at an old plot I did of a temperature controlled and air
pressure compensated LPRO against an M12+T, the Hadamard Deviation of
the 1000s averages of the 1PPS measurement was about 5E-14 at 1 day. 
A large part of that was likely the GPS, so with a better rubidium
like an FRK-H in a sealed and temperature controlled enclosure you
might be around 1E-14 at 1 day.

The bit that I'm not so sure about is the travelling. A long period of
movement, vibration, magnetic  fields, etc. all adding in could
obscure the effects of time dilation. 

It might be quite possible, although a nearby mountain and a friend
with a helicopter would make it a lot easier!

Angus.
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Re: [time-nuts] Time Dilation tinkering

[Bob Camp]

Hi

In this case, the vacuum might work against you. You change the pressure outside
the package and you get a flex. Flex translates to dimensional changes. That 
gives you
a frequency shift. People make absolute pressure sensors this way :) Rb’s are 
by no 
means the only frequency standard impacted by this effect. Precision OCXO’s 
have the
same issue.

If you had enough room inside the package, you could do a “can in a can” sort 
of approach. 
The outer vacuum sealed can flexes. The inner vacuum sealed can does not see 
anything. 
You don’t eliminate the sensitivity this way, you do attenuate it quite a bit 
with each layer. 
The question then becomes - is is worth the increase in size? Since the 
pressure sensitivity 
is well below many other environmental factors …. probably not.

Bob

> On Mar 22, 2017, at 1:04 AM, jimlux  wrote:
> 
> On 3/21/17 4:29 PM, Hal Murray wrote:
>> 
>> scmcgr...@gmail.com said:
>>> However CSAC not subject to barometric effects as Rb units are
>> 
>> Does anybody tried to measure CSAC vs pressure?
>> 
>> 
>> 
> The physics package in a CSAC is a vacuum, so it probably won't make much 
> difference.
> 
> But, as a practical matter, I have a system with a CSAC going through thermal 
> vacuum testing as I write this. We'll get some test data and we can compare 
> the frequency against GPS and a OCXO at room temp/pressure, and at various 
> temps in vacuum.
> 
> Remind me in 2 weeks, and I should have the data plotted.
> 
> 
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Re: [time-nuts] Time Dilation tinkering

[jimlux]

On 3/21/17 7:12 PM, Chris Albertson wrote:

"flight" there is the word.Why drive up a mountain?   Take the clock
with you inside the pressurized cabin of a commercial airliner next time
you are on one of those 10 hour trans=pacific flights.   You be taller then
any mountain and it is actually cheaper then a weather balloon.

Can you get a Rb clock past the TSA x-ray machine.   Maybe if you ask
first.  There must be a way to hand cary specialized equipment.




I hand carry specialized equipment all the time and let it go through 
the x-ray.   About 1 time out of 10, they'll ask to open it up so they 
can swab it for the explosives residue ion mobility machine. Nothing 
looks as suspicious as a big block of something with two wires come out 
of it (i.e. a 7Amp-hour 12V lead acid battery).


In fact, I did it yesterday with an unlabeled black pelican case holding 
a 8x10" PC board with a bunch of cards stacked on it.



While I have my NASA ID and a shipping document describing it, I've 
never had to show either. Driver's license, 55 year old guy who looks 
like an engineer, and so forth, so maybe I don't look like the notional 
threat?



When we hand carry "flight hardware" we do put it in a QA sealed (tape) 
antistatic bag, in a QA sealed container, with a special letter that's 
been coordinated 24 hours before with TSA. And we don't let it go 
through the X-ray (although not for any good reason that I know..). 
There's some process you're supposed to follow if they insist on opening 
it so you show up at the airport hours ahead of time.

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Re: [time-nuts] Time Dilation tinkering

[Michael Wouters]

Hmm, it appears that Symmetricom has an interpretation from IATA which
classifies their rubidium-containing products as non-hazardous.

I went through all of this some time ago because we were shipping
rubidiums about domestically (Australia) and there was no permissible
maximum qty of rubidium allowed on a passenger aircraft. It doesn't
make sense: any event which might have caused exposure of the rubidium
in a clock to water, was likely rather more severe than the effects of
less than 1 gram of rubidium igniting. Hard to argue these things
though.

Cheers
Michael
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Re: [time-nuts] Time Dilation tinkering

[Michael Wouters]

Dear Chris,

I believe IATA prohibits the carriage of any quantity of rubidium on
passenger aircraft.
You have to complete a "Dangerous Goods Declaration" and it then has
to go by cargo aircraft.

Cheers
Michael


On Wed, Mar 22, 2017 at 1:12 PM, Chris Albertson
 wrote:
> "flight" there is the word.Why drive up a mountain?   Take the clock
> with you inside the pressurized cabin of a commercial airliner next time
> you are on one of those 10 hour trans=pacific flights.   You be taller then
> any mountain and it is actually cheaper then a weather balloon.
>
> Can you get a Rb clock past the TSA x-ray machine.   Maybe if you ask
> first.  There must be a way to hand cary specialized equipment.
>
>
>
> On Tue, Mar 21, 2017 at 7:03 PM, Tom Van Baak  wrote:
>
>>
>> But attached is one of the first plots where I put a SA.32m in a home-brew
>> vacuum chamber and pulled down to a few inches of Hg for a few hours to
>> simulate the low pressure of a flight up to 50 or 90,000 ft. For a high
>> altitude relativity experiment -- where you'd like your clock to remain
>> stable to parts in e-13 and not accumulate too many stray ns -- it's not a
>> good sign when your clock changes by 2e-11 (that's more than 1 ns per
>> minute) just because of ambient pressure changes.
>>
> --
>
> Chris Albertson
> Redondo Beach, California
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Re: [time-nuts] Time Dilation tinkering

[Hugh Blemings]

Hi,

My profound thanks to Tom, Bob, Chris, Attila, Scott, Jim, Hal and 
Michael for such thorough and thoughtful replies to my initial post.


I'm fortunate enough to know some of the local amateur high altitude 
balloon crowd and had contemplated such an endeavour but note this 
wouldn't be feasible due to the pressure and temperature sensitivities 
of the Rb sources.


I had also thought the weight limitations might be a factor - an ardunio 
and a battery one thing to slow if things go wrong, a Rb clock and other 
bits a whole nother can of worms :)


I will still pick up one of the surplus Rb units and tinker with it, my 
GPSDO and my TAPR TICC that arrived the other day.


Slightly more pedestrian (but equally fun :) construction projects ahead 
I'm sure - keeping things stable in my garage in an Australian summer 
may yet prove challenge enough ;)


Thanks again

vy 73
Hugh
VK3YYZ/AD5RV


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Re: [time-nuts] Time Dilation tinkering

[Michael Wouters]

Yes, that's what I was quoted by the Microsemi agent and the price on
Mouser is similar.
The $1568 version was EOL'ed in December 2016; the more expensive unit is
the '2nd generation'.

Cheers
Michael

On Wed, 22 Mar 2017 at 9:06 am, jimlux  wrote:

> On 3/21/17 1:40 PM, Michael Wouters wrote:
> > These are less stable than a rubidium eg tau=10e-11@1000s and monthly
> > ageing of 9e-10.
> > The price of these has gone up  too- they're now about US5000.
> >
>
> Really? That's a big increase.  I bought some last year (well, in
> December 2015) and they were $1568 ea.
>
> It was a pain to buy them because Microsemi fell off JPL's approved
> supplier list.
>
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Re: [time-nuts] Time Dilation tinkering

[jimlux]

On 3/21/17 4:29 PM, Hal Murray wrote:


scmcgr...@gmail.com said:

However CSAC not subject to barometric effects as Rb units are


Does anybody tried to measure CSAC vs pressure?



The physics package in a CSAC is a vacuum, so it probably won't make 
much difference.


But, as a practical matter, I have a system with a CSAC going through 
thermal vacuum testing as I write this. We'll get some test data and we 
can compare the frequency against GPS and a OCXO at room temp/pressure, 
and at various temps in vacuum.


Remind me in 2 weeks, and I should have the data plotted.


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Re: [time-nuts] Time Dilation tinkering

[jimlux]

On 3/21/17 5:25 PM, Bob Camp wrote:

Hi

Ummm … e …. it’s a gas cell standard. I’d bet there is a pressure effect.



But the gas cell, the laser, etc. is in a vacuum - that's the "wear out" 
mechanism for a CSAC - the getter fills up, the pressure inside the 
vacuum package increases, and the heater can't keep it hot.


I'm speculating here... I don't really know enough about the guts of the 
CSAC to be sure.



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Re: [time-nuts] Time Dilation tinkering

[jimlux]

On 3/21/17 7:03 PM, Tom Van Baak wrote:

Yes, MAC and CSAC do show environmental sensitivity. But that should not be a 
surprise to anyone that works with precise time & frequency.

The factors include voltage, temperature, temperature gradient, pressure, 
humidity, acceleration, tilt (orientation), and who knows what else. Maybe even 
radiation? One looks for the *coefficient* of course, but also linearity, 
repeatability, hysteresis, and even interaction amongst factors. It's not an 
easy task to do this, nor can one assume each unit of a given make/model will 
be the same. I don't have comprehensive data or a nice report.

But attached is one of the first plots where I put a SA.32m in a home-brew 
vacuum chamber and pulled down to a few inches of Hg for a few hours to 
simulate the low pressure of a flight up to 50 or 90,000 ft. For a high 
altitude relativity experiment -- where you'd like your clock to remain stable 
to parts in e-13 and not accumulate too many stray ns -- it's not a good sign 
when your clock changes by 2e-11 (that's more than 1 ns per minute) just 
because of ambient pressure changes.




I wonder if the effect is due to vacuum, or something like thermal 
gradients (no convective heat transfer in vacuo)


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Re: [time-nuts] Time Dilation tinkering

[Chris Albertson]

"flight" there is the word.Why drive up a mountain?   Take the clock
with you inside the pressurized cabin of a commercial airliner next time
you are on one of those 10 hour trans=pacific flights.   You be taller then
any mountain and it is actually cheaper then a weather balloon.

Can you get a Rb clock past the TSA x-ray machine.   Maybe if you ask
first.  There must be a way to hand cary specialized equipment.



On Tue, Mar 21, 2017 at 7:03 PM, Tom Van Baak  wrote:

>
> But attached is one of the first plots where I put a SA.32m in a home-brew
> vacuum chamber and pulled down to a few inches of Hg for a few hours to
> simulate the low pressure of a flight up to 50 or 90,000 ft. For a high
> altitude relativity experiment -- where you'd like your clock to remain
> stable to parts in e-13 and not accumulate too many stray ns -- it's not a
> good sign when your clock changes by 2e-11 (that's more than 1 ns per
> minute) just because of ambient pressure changes.
>
-- 

Chris Albertson
Redondo Beach, California
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Re: [time-nuts] Time Dilation tinkering

[Bob Camp]

Hi

Ummm … e …. it’s a gas cell standard. I’d bet there is a pressure effect.

Bob

> On Mar 21, 2017, at 7:01 PM, Scott McGrath  wrote:
> 
> Noted
> 
> However CSAC not subject to barometric effects as Rb units are
> 
> Content by Scott
> Typos by Siri
> 
>> On Mar 21, 2017, at 4:18 PM, jimlux  wrote:
>> 
>>> On 3/21/17 12:51 PM, Scott McGrath wrote:
>>> Or perhaps use the Symmetricom CSAC ...
>>> 
>>> Relatively expensive but might work
>>> 
>> 
>> 
>> The CSAC  is 8E-12 AVAR at 1000 seconds, comparable to a Rb.
>> 
>> 
>> See also http://tycho.usno.navy.mil/ptti/2011papers/Paper27.pdf
>> which shows a bit better performance (3E-12 @ 1000s), but the best 
>> performance appears to be at 10,000 seconds.
>> 
>> 
>> but don't you need better?
>> Attila wrote> You will need a stability 1e-14 @1d.
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Re: [time-nuts] Time Dilation tinkering

[Hal Murray]

scmcgr...@gmail.com said:
> However CSAC not subject to barometric effects as Rb units are 

Does anybody tried to measure CSAC vs pressure?



-- 
These are my opinions.  I hate spam.



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Re: [time-nuts] Time Dilation tinkering

[Tom Van Baak]

Scott McGrath wrote:
> Or perhaps use the Symmetricom CSAC ...

Chris Albertson wrote:
> Get a weather balloon.  Or there might already be an amateur group that
> launches these.  Balloons can go much higher than your local mountains.

You'll both be interested to hear that CSAC+balloon was proposed for the 
"Genius by Stephen Hawking" TV program and, yes, we were in touch with amateur 
high altitude balloon groups. The producer rightly thought that a small atomic 
clock going up in a helium balloon would make dramatic video for a time 
dilation demonstration. Symmetricom / Microsemi donated a SA.* series clock to 
the effort.

I got involved on the science and engineering side of the equation. Spent a 
month trying to make it work and in the end the balloon idea was dropped. Just 
too hard, and too uncertain, and would require many more months of R, and 
finger crossing. So that's why, instead, I drove six calibrated 5071A down to 
Tucson for a conventional mountain-valley time dilation experiment -- which I 
knew from prior experience would work, especially with 3x redundancy. 
http://leapsecond.com/great2016a/

Note that miniature Rb and Cs clocks (such as those sold by Microsemi) are very 
small, ultra light, and amazingly low power -- but their long-term stability 
(including environmental effects) is a hundred or even a thousand times worse 
than a 5071A/001. This is not to say CSAC are poor clocks. In fact they have a 
superb mass/power/size to adev ratio, and thus there are many unique 
applications for them. But they are not designed to be laboratory-quality 
frequency standards

/tvb

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Re: [time-nuts] Time Dilation tinkering

[Scott McGrath]

Noted

However CSAC not subject to barometric effects as Rb units are

Content by Scott
Typos by Siri

> On Mar 21, 2017, at 4:18 PM, jimlux  wrote:
> 
>> On 3/21/17 12:51 PM, Scott McGrath wrote:
>> Or perhaps use the Symmetricom CSAC ...
>> 
>> Relatively expensive but might work
>> 
> 
> 
> The CSAC  is 8E-12 AVAR at 1000 seconds, comparable to a Rb.
> 
> 
> See also http://tycho.usno.navy.mil/ptti/2011papers/Paper27.pdf
> which shows a bit better performance (3E-12 @ 1000s), but the best 
> performance appears to be at 10,000 seconds.
> 
> 
> but don't you need better?
> Attila wrote> You will need a stability 1e-14 @1d.
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Re: [time-nuts] Time Dilation tinkering

[jimlux]

On 3/21/17 1:40 PM, Michael Wouters wrote:

These are less stable than a rubidium eg tau=10e-11@1000s and monthly
ageing of 9e-10.
The price of these has gone up  too- they're now about US5000.



Really? That's a big increase.  I bought some last year (well, in 
December 2015) and they were $1568 ea.


It was a pain to buy them because Microsemi fell off JPL's approved 
supplier list.


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Re: [time-nuts] Time Dilation tinkering

[Michael Wouters]

These are less stable than a rubidium eg tau=10e-11@1000s and monthly
ageing of 9e-10.
The price of these has gone up  too- they're now about US5000.

Cheers
Michael

On Wed, 22 Mar 2017 at 7:03 am, Scott McGrath  wrote:

> Or perhaps use the Symmetricom CSAC ...
>
> Relatively expensive but might work
>
> > On Mar 21, 2017, at 8:08 AM, Attila Kinali  wrote:
> >
> > On Tue, 21 Mar 2017 13:38:51 +1100
> > Hugh Blemings  wrote:
> >
> >> This got me to wondering if a Rubidium based standard might do the trick
> >> - the Efratom SLCR-101s seem readily available for ~USD$200 mark.
> >
> > As TvB wrote, a single one will not do the trick. You will need
> > a stability 1e-14 @1d. IIRC most Rb standards floor out at 1e-12 to 1e-13
> > somewhere between 1k and 100k seconds. Even the Super-5065 has a floor
> > of about 3-4e-14 (unless our friends here improved on this already).
> >
> > There will be a few things that you will need to do, if you want to go
> > with Rubidiums:
> > 1) Stabilize or compensate for environmental effects (temperature, air
> pressure)
> > 2) Build ensembles of Rb clocks.
> >
> > The former is to prevent the ADEV from "turning upwards" again and
> > keep the Rb's as stable as possible as long as possible. I have no
> > experience how much this helps, but I suspect, with the correct modeling
> > that you could get the ADEV to be flat up to a day, maybe even two.
> > You will have to include aging and drift of the cell itself in the model.
> > This also means that you will have your Rbs running for a few
> weeks/months
> > prior to any measurement so that the aging settles down a bit.
> >
> > The ensemble is to get the ADEV down. Averaging of clocks with the same
> > noise decreases the ADEV by the square root of the number of clocks used.
> > If you are close to the ADEV you need, the averaging will help you
> getting
> > it further down. Unfortunately, getting from 1e-13 down to 1e-14 is
> > impractical as you'd need 100 clocks to average over But a factor
> > of 2 to 3 should be possible.
> >
> >
> > Alternatively, you can ask Oscilloquartz whether they let you borrow
> > two of their new OSA3300 for a publicity stunt :-)
> >
> >Attila Kinali
> > --
> > It is upon moral qualities that a society is ultimately founded. All
> > the prosperity and technological sophistication in the world is of no
> > use without that foundation.
> > -- Miss Matheson, The Diamond Age, Neil Stephenson
> > ___
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Re: [time-nuts] Time Dilation tinkering

[jimlux]

On 3/21/17 12:51 PM, Scott McGrath wrote:

Or perhaps use the Symmetricom CSAC ...

Relatively expensive but might work




The CSAC  is 8E-12 AVAR at 1000 seconds, comparable to a Rb.


See also http://tycho.usno.navy.mil/ptti/2011papers/Paper27.pdf
which shows a bit better performance (3E-12 @ 1000s), but the best 
performance appears to be at 10,000 seconds.



but don't you need better?
Attila wrote> You will need a stability 1e-14 @1d.
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Re: [time-nuts] Time Dilation tinkering

[Scott McGrath]

Or perhaps use the Symmetricom CSAC ...

Relatively expensive but might work

> On Mar 21, 2017, at 8:08 AM, Attila Kinali  wrote:
> 
> On Tue, 21 Mar 2017 13:38:51 +1100
> Hugh Blemings  wrote:
> 
>> This got me to wondering if a Rubidium based standard might do the trick 
>> - the Efratom SLCR-101s seem readily available for ~USD$200 mark.
> 
> As TvB wrote, a single one will not do the trick. You will need 
> a stability 1e-14 @1d. IIRC most Rb standards floor out at 1e-12 to 1e-13
> somewhere between 1k and 100k seconds. Even the Super-5065 has a floor
> of about 3-4e-14 (unless our friends here improved on this already).
> 
> There will be a few things that you will need to do, if you want to go
> with Rubidiums:
> 1) Stabilize or compensate for environmental effects (temperature, air 
> pressure)
> 2) Build ensembles of Rb clocks.
> 
> The former is to prevent the ADEV from "turning upwards" again and
> keep the Rb's as stable as possible as long as possible. I have no
> experience how much this helps, but I suspect, with the correct modeling
> that you could get the ADEV to be flat up to a day, maybe even two.
> You will have to include aging and drift of the cell itself in the model.
> This also means that you will have your Rbs running for a few weeks/months
> prior to any measurement so that the aging settles down a bit.
> 
> The ensemble is to get the ADEV down. Averaging of clocks with the same
> noise decreases the ADEV by the square root of the number of clocks used.
> If you are close to the ADEV you need, the averaging will help you getting
> it further down. Unfortunately, getting from 1e-13 down to 1e-14 is
> impractical as you'd need 100 clocks to average over But a factor
> of 2 to 3 should be possible.
> 
> 
> Alternatively, you can ask Oscilloquartz whether they let you borrow
> two of their new OSA3300 for a publicity stunt :-)
>
>Attila Kinali
> -- 
> It is upon moral qualities that a society is ultimately founded. All 
> the prosperity and technological sophistication in the world is of no 
> use without that foundation.
> -- Miss Matheson, The Diamond Age, Neil Stephenson
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Re: [time-nuts] Time Dilation tinkering

[Chris Albertson]

Get a weather balloon.  Or there might already be an amateur group that
launches these.  Balloons can go much higher than your local mountains.
You al ill want to build an environmental chamber for the Rb clock.  The
chamber is heated and pressurized.

Even for the maintain top experiment you will need data on how the clock
reacts to the pressure and temperatures on the mountain and also along the
way to and from the mountain so you will need a way to simulate this at
home so you can measure the effect.   Maybe just as easy to keep the clocks
both in a sea level environment.

On Tue, Mar 21, 2017 at 4:28 AM, Bob Camp  wrote:

> H
>
> > On Mar 21, 2017, at 4:58 AM, Tom Van Baak  wrote:
> >
> > Hi Hugh,
> >
> >> If I do the math correctly that's about 14ns difference per 24h the
> >> clocks are separated by that altitude. [1]
> >
> > That's correct. For your 1500m elevation gain, the gravitational
> redshift, the df/f frequency change, will be about 1.6e-13. To be able to
> measure with any confidence you'll want your clocks to be stable to about
> 2e-14, at tau 1 or 2 days.
> >
> >> This got me to wondering if a Rubidium based standard might do the trick
> >> - the Efratom SLCR-101s seem readily available for ~USD$200 mark.
> >
> > There are tricks and technical factors, but the main one is how stable
> these are at tau 1 day. Buy or borrow a few of them and see if they are
> mutually stable to the level required. I suspect not. But perhaps other
> time nuts could comment on how stable their surplus Rb are out to tau 1 day.
> >
> > There are lots of other details; some to your advantage, some not. But
> if the surplus Rb can't perform down in the -14's at a day, even in
> laboratory conditions, then the rest of the discussion doesn't matter.
>
> An ex-telecom Rb will run a bit below 1x10^-12, but not below 1x10^-13 at
> tau = 1 day. Roughly speaking it’s about 10X less stable than you need.
> That’s in a carefully controlled temperature and pressure environment. One
> fake out with Rb’s is that they are pressure sensitive. You *will* see an
> impact simply from the lower pressure on the top of the mountain. How much
> impact varies from unit to unit. It’s a good bet you need to compensate for
> it well before you get to 1x10^-13 on a mountain trip.
>
> To put this all in context, a 5071 in good condition can (barely) do this
> experiment by running up to a mountain top. There’s a lot of fiddly details
> you need to take care of even with a 5071.  AFIK, Tom is the first to do it
> this way (Cs in the back of the family car). All previous work with older
> Cs standards had to go to much greater lengths to observe the effect. If
> you take a standard up to satellite orbit sort of altitude, you get a shift
> of ~1.5x10^-10. That would be fine for a number of frequency standards. It
> is not very practical on the transport side of the experiment.
>
> Many options, but none of them easy.
>
> Bob
>
> >
> > Yes, the TAPR TICC counter would work well for this experiment. But to
> be honest, any old nanosecond-level counter is good enough. I say this not
> to discourage you from a good excuse to buy a TICC, but to encourage you to
> do the ADEV math to see how clocks and counters and tau can interact in
> your favor.
> >
> > /tvb
> >
> > - Original Message -
> > From: "Hugh Blemings" 
> > To: "Discussion of precise time and frequency measurement" <
> time-nuts@febo.com>
> > Sent: Monday, March 20, 2017 7:38 PM
> > Subject: [time-nuts] Time Dilation tinkering
> >
> >
> >> Hi,
> >>
> >> I've been mostly lurking on the list for some time now and follow with
> >> interest the many discussions.  Very much at the early stages of my
> >> time-nut journey, but enjoying it so far :)
> >>
> >> I'd like to have a go at re-creating the efforts of Tom (and I gather
> >> others) in taking a clock up a mountain for a while and seeing if I can
> >> measure the relativistic changes.
> >>
> >> Being based in Australia gives me a couple of challenges, for one we
> >> don't really do mountains in the same sense as much of the rest of the
> >> world - so the highest peak I can readily get to from Melbourne is about
> >> 1,600m ASL.  I live at 80m ASL - so a delta of around 1,500m altitude
> >> and several hundred km drive.
> >>
> >> If I do the math correctly that's about 14ns difference per 24h the
> >> clocks are separated by that altitude. [1]
> >>
> >> We also lack quite the same surplus market here as the US, so purchasing
> >> a Caesium based standard is well beyond my means.
> >>
> >> This got me to wondering if a Rubidium based standard might do the trick
> >> - the Efratom SLCR-101s seem readily available for ~USD$200 mark.
> >>
> >> Clearly there'd need to be a bunch of extra gubbins [2] added to the
> >> 10MHz standard to turn it into an actual clock/counter including battery
> >> backup and so forth.  And would need a pair of everything.
> >>
> >> Before I delve 

Re: [time-nuts] Time Dilation tinkering

[Attila Kinali]

On Tue, 21 Mar 2017 13:38:51 +1100
Hugh Blemings  wrote:

> This got me to wondering if a Rubidium based standard might do the trick 
> - the Efratom SLCR-101s seem readily available for ~USD$200 mark.

As TvB wrote, a single one will not do the trick. You will need 
a stability 1e-14 @1d. IIRC most Rb standards floor out at 1e-12 to 1e-13
somewhere between 1k and 100k seconds. Even the Super-5065 has a floor
of about 3-4e-14 (unless our friends here improved on this already).

There will be a few things that you will need to do, if you want to go
with Rubidiums:
1) Stabilize or compensate for environmental effects (temperature, air pressure)
2) Build ensembles of Rb clocks.

The former is to prevent the ADEV from "turning upwards" again and
keep the Rb's as stable as possible as long as possible. I have no
experience how much this helps, but I suspect, with the correct modeling
that you could get the ADEV to be flat up to a day, maybe even two.
You will have to include aging and drift of the cell itself in the model.
This also means that you will have your Rbs running for a few weeks/months
prior to any measurement so that the aging settles down a bit.

The ensemble is to get the ADEV down. Averaging of clocks with the same
noise decreases the ADEV by the square root of the number of clocks used.
If you are close to the ADEV you need, the averaging will help you getting
it further down. Unfortunately, getting from 1e-13 down to 1e-14 is
impractical as you'd need 100 clocks to average over But a factor
of 2 to 3 should be possible.


Alternatively, you can ask Oscilloquartz whether they let you borrow
two of their new OSA3300 for a publicity stunt :-)

Attila Kinali
-- 
It is upon moral qualities that a society is ultimately founded. All 
the prosperity and technological sophistication in the world is of no 
use without that foundation.
 -- Miss Matheson, The Diamond Age, Neil Stephenson
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Re: [time-nuts] Time Dilation tinkering

[Bob Camp]

H

> On Mar 21, 2017, at 4:58 AM, Tom Van Baak  wrote:
> 
> Hi Hugh,
> 
>> If I do the math correctly that's about 14ns difference per 24h the 
>> clocks are separated by that altitude. [1]
> 
> That's correct. For your 1500m elevation gain, the gravitational redshift, 
> the df/f frequency change, will be about 1.6e-13. To be able to measure with 
> any confidence you'll want your clocks to be stable to about 2e-14, at tau 1 
> or 2 days.
> 
>> This got me to wondering if a Rubidium based standard might do the trick 
>> - the Efratom SLCR-101s seem readily available for ~USD$200 mark.
> 
> There are tricks and technical factors, but the main one is how stable these 
> are at tau 1 day. Buy or borrow a few of them and see if they are mutually 
> stable to the level required. I suspect not. But perhaps other time nuts 
> could comment on how stable their surplus Rb are out to tau 1 day.
> 
> There are lots of other details; some to your advantage, some not. But if the 
> surplus Rb can't perform down in the -14's at a day, even in laboratory 
> conditions, then the rest of the discussion doesn't matter.

An ex-telecom Rb will run a bit below 1x10^-12, but not below 1x10^-13 at tau = 
1 day. Roughly speaking it’s about 10X less stable than you need. That’s in a 
carefully controlled temperature and pressure environment. One fake out with 
Rb’s is that they are pressure sensitive. You *will* see an impact simply from 
the lower pressure on the top of the mountain. How much impact varies from unit 
to unit. It’s a good bet you need to compensate for it well before you get to 
1x10^-13 on a mountain trip. 

To put this all in context, a 5071 in good condition can (barely) do this 
experiment by running up to a mountain top. There’s a lot of fiddly details you 
need to take care of even with a 5071.  AFIK, Tom is the first to do it this 
way (Cs in the back of the family car). All previous work with older Cs 
standards had to go to much greater lengths to observe the effect. If you take 
a standard up to satellite orbit sort of altitude, you get a shift of 
~1.5x10^-10. That would be fine for a number of frequency standards. It is not 
very practical on the transport side of the experiment. 

Many options, but none of them easy. 

Bob

> 
> Yes, the TAPR TICC counter would work well for this experiment. But to be 
> honest, any old nanosecond-level counter is good enough. I say this not to 
> discourage you from a good excuse to buy a TICC, but to encourage you to do 
> the ADEV math to see how clocks and counters and tau can interact in your 
> favor.
> 
> /tvb
> 
> - Original Message - 
> From: "Hugh Blemings" 
> To: "Discussion of precise time and frequency measurement" 
> 
> Sent: Monday, March 20, 2017 7:38 PM
> Subject: [time-nuts] Time Dilation tinkering
> 
> 
>> Hi,
>> 
>> I've been mostly lurking on the list for some time now and follow with 
>> interest the many discussions.  Very much at the early stages of my 
>> time-nut journey, but enjoying it so far :)
>> 
>> I'd like to have a go at re-creating the efforts of Tom (and I gather 
>> others) in taking a clock up a mountain for a while and seeing if I can 
>> measure the relativistic changes.
>> 
>> Being based in Australia gives me a couple of challenges, for one we 
>> don't really do mountains in the same sense as much of the rest of the 
>> world - so the highest peak I can readily get to from Melbourne is about 
>> 1,600m ASL.  I live at 80m ASL - so a delta of around 1,500m altitude 
>> and several hundred km drive.
>> 
>> If I do the math correctly that's about 14ns difference per 24h the 
>> clocks are separated by that altitude. [1]
>> 
>> We also lack quite the same surplus market here as the US, so purchasing 
>> a Caesium based standard is well beyond my means.
>> 
>> This got me to wondering if a Rubidium based standard might do the trick 
>> - the Efratom SLCR-101s seem readily available for ~USD$200 mark.
>> 
>> Clearly there'd need to be a bunch of extra gubbins [2] added to the 
>> 10MHz standard to turn it into an actual clock/counter including battery 
>> backup and so forth.  And would need a pair of everything.
>> 
>> Before I delve too far into the planning, I'd be interested in feedback 
>> as to whether this style of Rb standard is likely to be up to the task 
>> of being the core of such an endeavour or not ?
>> 
>> Oh I should add - my plan was to build the systems such that they 
>> function as nice standalone time/frequency references once this 
>> experiment is concluded :)
>> 
>> Thanks in advance,
>> 
>> Kind Regards/73,
>> Hugh
>> VK3YYZ/AD5RV
>> 
>> 
>> 
>> [1] gh/c^2 x 3600 x 24  Where h is 1500, g and c the usual values :)
>> 
>> [2] I presume at a minimum a counter running at a 5ns or less "tick" fed 
>> from a frequency source locked to the 10MHz of the Rb standard.  This 
>> counter would need to be latched for reading from an external signal 

Re: [time-nuts] Time Dilation tinkering

[Tom Van Baak]

Hi Hugh,

> If I do the math correctly that's about 14ns difference per 24h the 
> clocks are separated by that altitude. [1]

That's correct. For your 1500m elevation gain, the gravitational redshift, the 
df/f frequency change, will be about 1.6e-13. To be able to measure with any 
confidence you'll want your clocks to be stable to about 2e-14, at tau 1 or 2 
days.

> This got me to wondering if a Rubidium based standard might do the trick 
> - the Efratom SLCR-101s seem readily available for ~USD$200 mark.

There are tricks and technical factors, but the main one is how stable these 
are at tau 1 day. Buy or borrow a few of them and see if they are mutually 
stable to the level required. I suspect not. But perhaps other time nuts could 
comment on how stable their surplus Rb are out to tau 1 day.

There are lots of other details; some to your advantage, some not. But if the 
surplus Rb can't perform down in the -14's at a day, even in laboratory 
conditions, then the rest of the discussion doesn't matter.

Yes, the TAPR TICC counter would work well for this experiment. But to be 
honest, any old nanosecond-level counter is good enough. I say this not to 
discourage you from a good excuse to buy a TICC, but to encourage you to do the 
ADEV math to see how clocks and counters and tau can interact in your favor.

/tvb

- Original Message - 
From: "Hugh Blemings" 
To: "Discussion of precise time and frequency measurement" 
Sent: Monday, March 20, 2017 7:38 PM
Subject: [time-nuts] Time Dilation tinkering


> Hi,
> 
> I've been mostly lurking on the list for some time now and follow with 
> interest the many discussions.  Very much at the early stages of my 
> time-nut journey, but enjoying it so far :)
> 
> I'd like to have a go at re-creating the efforts of Tom (and I gather 
> others) in taking a clock up a mountain for a while and seeing if I can 
> measure the relativistic changes.
> 
> Being based in Australia gives me a couple of challenges, for one we 
> don't really do mountains in the same sense as much of the rest of the 
> world - so the highest peak I can readily get to from Melbourne is about 
> 1,600m ASL.  I live at 80m ASL - so a delta of around 1,500m altitude 
> and several hundred km drive.
> 
> If I do the math correctly that's about 14ns difference per 24h the 
> clocks are separated by that altitude. [1]
> 
> We also lack quite the same surplus market here as the US, so purchasing 
> a Caesium based standard is well beyond my means.
> 
> This got me to wondering if a Rubidium based standard might do the trick 
> - the Efratom SLCR-101s seem readily available for ~USD$200 mark.
> 
> Clearly there'd need to be a bunch of extra gubbins [2] added to the 
> 10MHz standard to turn it into an actual clock/counter including battery 
> backup and so forth.  And would need a pair of everything.
> 
> Before I delve too far into the planning, I'd be interested in feedback 
> as to whether this style of Rb standard is likely to be up to the task 
> of being the core of such an endeavour or not ?
> 
> Oh I should add - my plan was to build the systems such that they 
> function as nice standalone time/frequency references once this 
> experiment is concluded :)
> 
> Thanks in advance,
> 
> Kind Regards/73,
> Hugh
> VK3YYZ/AD5RV
> 
> 
> 
> [1] gh/c^2 x 3600 x 24  Where h is 1500, g and c the usual values :)
> 
> [2] I presume at a minimum a counter running at a 5ns or less "tick" fed 
> from a frequency source locked to the 10MHz of the Rb standard.  This 
> counter would need to be latched for reading from an external signal so 
> that it can be compared to the second clock.  Not sure but seems the 
> TAPR TICC might have role here :)
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