Attila Kinali wrote:
> Mike Cook wrote:
>
> > c. The first commercial cesium clocks were available in 1956, but the
> > second did not get redefined until 1967. There is no rush.
>
> Which caesium beam standards were available in 1956?
The Atomichron, I think:
Mike, Attila, Rick,
> Which caesium beam standards were available in 1956?
The Atomichron, made by the National Company. This was the first
commercial cesium standard; about 50 were made. Attila, you saw one at
my house when you visited last year. It's about 7 feet tall. The one I
have was
On 6/3/19 8:52 AM, Richard (Rick) Karlquist wrote:
FWIW, there is a nice article in IEEE Spectrum, Oct. 2014, page 42 on
OLC's that starts out by showing the 1956 (non-commerical) clock by
Parry and Essen. It has a tutorial on OLC's and a history of the
second. The author is Prof.
On 5/29/2019 6:16 AM, Attila Kinali wrote:
On Tue, 28 May 2019 22:56:35 +0200
Mike Cook wrote:
c. The first commercial cesium clocks were available in 1956, but the second
did not get redefined until 1967. There is no rush.
Which caesium beam standards were available in 1956? AFAIK
Hi
I believe the “guess” is that all will be met within a year or three.
Bob
> On May 29, 2019, at 12:22 PM, Dana Whitlow wrote:
>
> Ole,
>
> Is it when all 5 conditions are met, or just any one of them?
>
> Thanks,
>
> Dana
>
>
> On Wed, May 29, 2019 at 11:00 AM Ole Petter Rønningen
>
Hi, Dana
My understanding is that all criteria should be met, but the list might be
refined. Dr. Martin Milton, Director of the BIPM gave a talk on the subject
on this years IFCS/EFTF; https://www.youtube.com/watch?v=Qsgl8AHBU7c
(redefinition
of the second at around 33 minutes, but the whole talk
Ole,
Is it when all 5 conditions are met, or just any one of them?
Thanks,
Dana
On Wed, May 29, 2019 at 11:00 AM Ole Petter Rønningen
wrote:
> As supporting material; BIPM is considering when a redefinition would be
> appropriate:
>
As supporting material; BIPM is considering when a redefinition would be
appropriate:
https://www.bipm.org/utils/common/pdf/CGPM-2018/CGPM-2018-Time-2-LD.pdf
And
https://www.bipm.org/utils/en/pdf/CCTF-strategy-document.pdf annex 1 (and a few
other places)
Extract:
The time for a new
On Tue, 28 May 2019 22:56:35 +0200
Mike Cook wrote:
> a. There is no need for a new definition.
There is. Current optical clocks deliver a lower uncertainty than
Cs fountain clocks. Ie the reference we have is less precise than
the measurement tools we have. Hence a redefinition of the second
> Le 27 mai 2019 à 11:13, Dave B via time-nuts a
> écrit :
>
> Hi.
>
> This from the recent ShortWave Radiogram broadcast, may be of interest.
>
> ~ ~ ~
>
> (Snipped stuff about other SI units undergoing a revamp...)
>
> Scientists now have their sights set on updating the unit of
> time:
On 5/28/19 2:12 AM, Attila Kinali wrote:
On Tue, 28 May 2019 03:06:12 +0100
Another way to look at it is, before you reach the point where the
redefinition of the kg change becomes visible, other errors like
buoyancy of air will introduce errors that are orders of magnitude
largers
On Tue, 28 May 2019 03:06:12 +0100
"Dr. David Kirkby" wrote:
> I notice a lot of 1 kg weights on eBay, so perhaps the same will happen
> with Cs clocks!
This is rather unlikely. For one, Cs beam standards have a very limited
life span. For an other I am pretty sure that the surge of kg weight
On Mon, 27 May 2019 at 11:20, Dave B via time-nuts
wrote:
>
>
> https://www.sciencenews.org/article/kilogram-just-got-revamp-unit-time-might-be-next
>
> ~ ~ ~
>
> So, perhaps a host of surplus cesium clocks on the market at some point?
>
> 73
>
> Dave B G0WBX.
I notice a lot of 1 kg weights on
Just as a side note.. I have looked at the propagation of DTV pilot carriers
(as part of an "over the horizon" VHF radio propagation experiment) and the
Doppler shifted carriers due to reflections from air craft were typically
detected separately along with the "over the horizon" pilot carrier
Well, I once had a nutty idea which was to detect earthquakes by looking
for the phase
variation of DTV station pilot carriers due to seismic waves propagating
around, thereby
changing the physical distance between transmitter and receiver in a cyclic
manner
until the 'quake calmed down. Doing
Well I have enjoyed time and frequency measurement for many years. I have no
equipment (nor do I expect to get any) that can tell the difference between the
current second and the proposed standard. And at one point I asked if there
was a limit on the smallest time interval that could be
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