Re: [time-nuts] Smart Phone time display accuracy...?

[Jeremy Nichols]

I have that app but don't see an option to display "the offset between 
NTP time and the device's internal clock." Please guide me.


Jeremy


On 3/18/2017 9:37 AM, Glen Hoag wrote:

On my iPhone, I run an NTP client, Emerald Time, that displays the offset 
between NTP time and the device's internal clock.

I'm on T-Mobile US and the offset is typically in the low tens of milliseconds 
or better.

It's certainly accurate enough as a clock where all I'm looking at is one 
minute resolution.

Glen Hoag
h...@hiwaay.net
Sent from my iPhone


On Mar 18, 2017, at 09:52, John Hawkinson  wrote:

Chris Albertson  wrote on Fri, 17 Mar 2017
at 14:38:17 -0700 in 

[time-nuts] Optical Cesium or maybe Cesium "light"!

[Mark Sims]

Here's some marketing eyewash for the thing... it has a 100 MHz output...

http://www.heritek.com.cn/Private/Files/3037bb9d8c45dac855ad.pdf

Darn it... I just bought a 5071A.
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Re: [time-nuts] Optical Cesium or maybe Cesium "light"!

[Bob Camp]

Hi

Get a bigger bag :)

Bob

> On Mar 18, 2017, at 4:45 PM, Wojciech Owczarek  
> wrote:
> 
> I tried lifting it but it wouldn't fit in my bag :(
> 
> 
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Re: [time-nuts] Optical Cesium or maybe Cesium "light"!

[Wojciech Owczarek]

I tried lifting it but it wouldn't fit in my bag :(


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Re: [time-nuts] Smart Phone time display accuracy...?

[Glen Hoag]

On my iPhone, I run an NTP client, Emerald Time, that displays the offset 
between NTP time and the device's internal clock. 

I'm on T-Mobile US and the offset is typically in the low tens of milliseconds 
or better. 

It's certainly accurate enough as a clock where all I'm looking at is one 
minute resolution. 

Glen Hoag
h...@hiwaay.net
Sent from my iPhone

> On Mar 18, 2017, at 09:52, John Hawkinson  wrote:
> 
> Chris Albertson  wrote on Fri, 17 Mar 2017
> at 14:38:17 -0700 in 
> 

Re: [time-nuts] Optical Cesium or maybe Cesium "light"!

[Magnus Danielson]

Hi,

On 03/18/2017 08:25 PM, Poul-Henning Kamp wrote:


In message <2254f8a0-9ea7-e0d3-18d7-90918985c...@rubidium.dyndns.org>, Magnus D
anielson writes:


The A magnet being replaced by the A laser will for the same flow from
the cesium oven produce twice as much atoms and thus improve signal to
noise.


It will generate more than twice the (usable) atoms, becuase the
straight path is (almost) insensitive to their velocity distribution,
whereas the corner-turning at the magnet is not.


True. I was just taking the state selection as such, not other actions 
ini the bending.



Not sure if their "100x" claim holds, but it is not patently impossible.

However, the slide-decks claim that atoms are "reused" is 100% bogus.


Until tested, I would take such claims with not only one but several 
pinches salt.



I also expect that the optical detection does not experience the
same wear mechanisms as the traditional setup. Laser wear is however a
concern, but easier to handle.


That is probably why they have "two redundant laser modules", a complication
they cannot possibly have accepted if they didn't need it.


Indeed. It reduces the downtime, but even then you would have downtime 
to restore redundancy. Hotpluging would be an option, but that always 
take some mechanical headache to get working, but for optical stuff has 
become simpler these days.


Cheers,
Magnus
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Re: [time-nuts] Optical Cesium or maybe Cesium "light"!

[Magnus Danielson]

Hi Paul,

On 03/18/2017 03:32 PM, paul swed wrote:

I am in the same frame of mind had the market, so no need to evolve. But
also it seems the business segment is so small its unclear that there is a
good business case to build them.These days if its not $B little interest.
Chuckle.
Hp dumped cesiums and test equipment and then symetricom was purchased by
Microsemi. Pretty strange. All in all in the timing market the players seem
to be all but gone.


Some vendors have been unable to adapt, so they loose market share, cut 
products and markets and eventually end up selling the business to some 
large player, get consolidated and eventually vanish as a brand. Some of 
these created some product which fit a market very well, but later the 
solution for that market is tighter integrated and the market is gone, 
but there is still lots of timing in there.


At the same time, others come in, silently builds larger and pick market 
shares.


As always, things change.

We time-nuts must be careful to save away all useful material when we 
can, so that we don't loose manuals, software, app-notes, etc. We cannot 
take for granted it will be there next year.


Cheers,
Magnus
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Re: [time-nuts] Optical Cesium or maybe Cesium "light"!

[Poul-Henning Kamp]

In message <2254f8a0-9ea7-e0d3-18d7-90918985c...@rubidium.dyndns.org>, Magnus D
anielson writes:

>The A magnet being replaced by the A laser will for the same flow from 
>the cesium oven produce twice as much atoms and thus improve signal to 
>noise.

It will generate more than twice the (usable) atoms, becuase the
straight path is (almost) insensitive to their velocity distribution,
whereas the corner-turning at the magnet is not.

Not sure if their "100x" claim holds, but it is not patently impossible.

However, the slide-decks claim that atoms are "reused" is 100% bogus.

>I also expect that the optical detection does not experience the 
>same wear mechanisms as the traditional setup. Laser wear is however a 
>concern, but easier to handle.

That is probably why they have "two redundant laser modules", a complication
they cannot possibly have accepted if they didn't need it.

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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Re: [time-nuts] Optical Cesium or maybe Cesium "light"!

[Poul-Henning Kamp]

In message <7765b488-bc22-d5af-3f62-d356e4aac...@karlquist.com>, "Richard (Rick
) Karlquist" writes:

>NIST-7 has a reversible beam, which cancels out end to end phase
>error in the CBT.  That works in terms of being a frequency standard,
>but not for a clock, because you don't have continuous operation.

You could build one with two beams running opposite directions and still
using the same laser light and RF field, but it would be more complicated.

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
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Re: [time-nuts] Optical Cesium or maybe Cesium "light"!

[paul swed]

Did take a look at the various papers. The older Osciliquartz document does
overlap the new one. But the old one actually supplies more details. Good
reads.
It is interesting that the major consumable components like laser diodes
are all external. So what is the true life of the unit. Pretty curious and
suspect its far beyond 10 years.
Also power consumption is 35 watts or a running savings of 30% over the
5071.
Pretty sure we will see these on ebay in the next few years NOT
Regards
Paul
WB8TSL

On Sat, Mar 18, 2017 at 10:32 AM, paul swed  wrote:

> I am in the same frame of mind had the market, so no need to evolve. But
> also it seems the business segment is so small its unclear that there is a
> good business case to build them.These days if its not $B little interest.
> Chuckle.
> Hp dumped cesiums and test equipment and then symetricom was purchased by
> Microsemi. Pretty strange. All in all in the timing market the players seem
> to be all but gone.
> Regards
> Paul
> WB8TSL
>
> On Sat, Mar 18, 2017 at 4:56 AM, Poul-Henning Kamp 
> wrote:
>
>> 
>> In message <45f89398-9302-80dc-3b9d-690802c46...@karlquist.com>,
>> "Richard (Rick) Karlquist" write
>> s:
>>
>> >It is surprising that none of the various makers of the 5071A
>> >ever made an optical version.  I wonder what they are thinking
>> >now that someone else has done it.
>>
>> Why would they ?
>>
>> They had a pretty good gig going with no competition...
>>
>>
>> --
>> Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
>> p...@freebsd.org | TCP/IP since RFC 956
>> FreeBSD committer   | BSD since 4.3-tahoe
>> Never attribute to malice what can adequately be explained by
>> incompetence.
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>> ailman/listinfo/time-nuts
>> and follow the instructions there.
>>
>
>
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Re: [time-nuts] Optical Cesium or maybe Cesium "light"!

[paul swed]

I am in the same frame of mind had the market, so no need to evolve. But
also it seems the business segment is so small its unclear that there is a
good business case to build them.These days if its not $B little interest.
Chuckle.
Hp dumped cesiums and test equipment and then symetricom was purchased by
Microsemi. Pretty strange. All in all in the timing market the players seem
to be all but gone.
Regards
Paul
WB8TSL

On Sat, Mar 18, 2017 at 4:56 AM, Poul-Henning Kamp 
wrote:

> 
> In message <45f89398-9302-80dc-3b9d-690802c46...@karlquist.com>, "Richard
> (Rick) Karlquist" write
> s:
>
> >It is surprising that none of the various makers of the 5071A
> >ever made an optical version.  I wonder what they are thinking
> >now that someone else has done it.
>
> Why would they ?
>
> They had a pretty good gig going with no competition...
>
>
> --
> Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
> p...@freebsd.org | TCP/IP since RFC 956
> FreeBSD committer   | BSD since 4.3-tahoe
> Never attribute to malice what can adequately be explained by incompetence.
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> mailman/listinfo/time-nuts
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>
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Re: [time-nuts] Optical Cesium or maybe Cesium "light"!

[Magnus Danielson]

Rick,

On 03/18/2017 05:32 PM, Richard (Rick) Karlquist wrote:



On 3/18/2017 3:13 AM, Magnus Danielson wrote:

The NIST-7 was a optically pumped cesium beam, and a pre-cursor to the
fountain clocks. There should be a bunch of papers on it.



I am however somewhat wondering about if we will see this coming out of
Oscilloquartz. We will see.



NIST-7 has a reversible beam, which cancels out end to end phase
error in the CBT.  That works in terms of being a frequency standard,
but not for a clock, because you don't have continuous operation.
NIST-7 is also much longer than the 5071A or the Oscilloquartz offering.
So they are not really comparable beyond sharing optical pumping.


I think you misunderstood my comment quite a bit.
It is merely a suggestion to find more articles on the topic of optical 
pumpning beams.


One problem with the NIST-7 is also the poor S/N. It was used more for 
frequency than continuous clock, but free-wheeling on commercial clocks 
helps for the ensamble behavior.


Cheers,
Magnus
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Re: [time-nuts] Optical Cesium or maybe Cesium "light"!

[Richard (Rick) Karlquist]

On 3/18/2017 3:13 AM, Magnus Danielson wrote:

The NIST-7 was a optically pumped cesium beam, and a pre-cursor to the
fountain clocks. There should be a bunch of papers on it.



I am however somewhat wondering about if we will see this coming out of
Oscilloquartz. We will see.



NIST-7 has a reversible beam, which cancels out end to end phase
error in the CBT.  That works in terms of being a frequency standard,
but not for a clock, because you don't have continuous operation.
NIST-7 is also much longer than the 5071A or the Oscilloquartz offering.
So they are not really comparable beyond sharing optical pumping.

Rick
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Re: [time-nuts] Smart Phone time display accuracy...?

[John Hawkinson]

Chris Albertson  wrote on Fri, 17 Mar 2017
at 14:38:17 -0700 in 

Re: [time-nuts] Antique precision timing device without

[Bob Camp]

Hi



> On Mar 17, 2017, at 7:41 PM, Morris Odell  wrote:
> 
> HI all,
> 
> Thanks to all those who responded to my post and also for the great pics of
> other tuning forks. It's amazing that they were still being used for
> electronic purposes as recently as the 1960s.

Motorola was still very much in the business of making Vibrasenders and 
Vibrasponders
to generate and decode PL tones on FM radios well into the 1980’s. They were 
really not much more than tuning forks set to the proper tone frequency.

Bob


> Actually now that I think
> about it I have seen little tuning forks used to check the function of
> modern police speed radars so they still have some use. Musicians don't use
> them any more - guitar players will know the little electronic tuning
> devices clipped to the  neck of the instrument that displays the frequency
> or key of each string. Doctors still use 125 Hz forks to test vibration
> sense and higher frequency ones to test for conductive hearing loss. 
> 
> In answer to some of the questions posted: no there was no documentation
> with the unit. The most useful thing was the "12 volts in" label on the
> power socket so I knew where to start. The rest of it was necktop analysis.
> The fork is maintained by means of a central electromagnet and small leaf
> spring contacts on the tines - they also provide the 25 Hz power for the
> motor which runs at 12 volts. Of course they would reduce the Q of the fork
> a little and affect its resonance but I'm sure that was taken into  account
> by the designer and the frequency & symmetry can be adjusted with the
> weights on the ends. Operating current is about 0.5A at 12 volts when
> running and 1A when the fork is not vibrating. There's a switch marked "Neon
> Lamp" that controls the AC supply to a pair of clips between the tines of
> the fork. They are about 3-4 inches apart and I have no idea what sort of
> long thin tubular lamp would fit between them. Just for fun I'm going to
> make a simple stroboscope with a 555 timer and some high intensity white
> LEDs I have lying around to see if I can use it on the fork.
> 
> Cheers,
> 
> Morris
> 
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Re: [time-nuts] Optical Cesium or maybe Cesium "light"!

[Magnus Danielson]

The NIST-7 was a optically pumped cesium beam, and a pre-cursor to the 
fountain clocks. There should be a bunch of papers on it.


If you look on the picture from wikipedia:

https://en.wikipedia.org/wiki/NIST-7

You can see the optical bench on top of the electronics rack.

The modern books go into length about the issues of laser pumping and 
detection, so there is plenty of material to work from.


The A magnet being replaced by the A laser will for the same flow from 
the cesium oven produce twice as much atoms and thus improve signal to 
noise. I also expect that the optical detection does not experience the 
same wear mechanisms as the traditional setup. Laser wear is however a 
concern, but easier to handle.


I am however somewhat wondering about if we will see this coming out of 
Oscilloquartz. We will see.


Cheers,
Magnus

On 03/18/2017 09:05 AM, Bruce Griffiths wrote:

An Early (~1980?) NS/FEI paper on optically pumped cesium beam tubes:

http://tf.nist.gov/general/pdf/732.pdf

Bruce



On 18 March 2017 at 17:28 "Richard (Rick) Karlquist" 
 wrote:

Len Cutler was all set to build an optically
pumped Cs beam 20 years ago. Even then, he could get the lasers.
He was only missing one thing: money. HP management never
agreed to fund it. The paper conspicuously omits any spec
on absolute accuracy. The optical pumping does nothing to
improve that AFAIK. It still depends on phase error in the CBT.
The 5071 has a guaranteed accuracy of 10^-12, and is typically
several times better than that.

It is surprising that none of the various makers of the 5071A
ever made an optical version. I wonder what they are thinking
now that someone else has done it.

Rick

On 3/17/2017 7:48 PM, cdel...@juno.com wrote:

> >

Looks like Oscilloquartz is getting ready to sell this commercially!
Will give the 5071A a run for the money!
Reliability should go way up as:
-No electron multiplier
-No ionizer filament
-No state selection magnets
Also all the fiddley bits (laser diodes and photodetectors) are external
to the tube and can be easily updated as needed.


https://www.slideshare.net/ADVAOpticalNetworking/performance-results-of-a
n-optically-pumped-cesium-beam-clock

Cheers,

Corby

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>

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Re: [time-nuts] Optical Cesium or maybe Cesium "light"!

[Poul-Henning Kamp]

In message <45f89398-9302-80dc-3b9d-690802c46...@karlquist.com>, "Richard 
(Rick) Karlquist" write
s:

>It is surprising that none of the various makers of the 5071A
>ever made an optical version.  I wonder what they are thinking
>now that someone else has done it.

Why would they ?

They had a pretty good gig going with no competition...


-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
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Re: [time-nuts] Antique precision timing device without electronics

[Poul-Henning Kamp]

In message <20170317220437.4a4ff406...@ip-64-139-1-69.sjc.megapath.net>, Hal 
Murray writes:
>
>e...@scace.org said:
>>Frequencies around 15 Hz were common on early 20th century cables,
>> depending on the degree of success in compensating for the inherent
>> capacitance on a cable thousands of miles long surrounded by conductive
>> sea water.
>
>Is the sea water relevant?

Not in a coaxial cable, unless it gets into the cable.

Most telegraph cables where not coaxial and used the sea-water as return path.

>Does enough energy leak through the shield so that it matters?  How well does 
>coax work at low frequencies?

Coax is near perfect at low frequencies, but the lengths of these
cables introduced geophysics as a number of sources of noise.

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
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Re: [time-nuts] Optical Cesium or maybe Cesium "light"!

[Bruce Griffiths]

An Early (~1980?) NS/FEI paper on optically pumped cesium beam tubes:

http://tf.nist.gov/general/pdf/732.pdf

Bruce

> 
> On 18 March 2017 at 17:28 "Richard (Rick) Karlquist" 
>  wrote:
> 
> Len Cutler was all set to build an optically
> pumped Cs beam 20 years ago. Even then, he could get the lasers.
> He was only missing one thing: money. HP management never
> agreed to fund it. The paper conspicuously omits any spec
> on absolute accuracy. The optical pumping does nothing to
> improve that AFAIK. It still depends on phase error in the CBT.
> The 5071 has a guaranteed accuracy of 10^-12, and is typically
> several times better than that.
> 
> It is surprising that none of the various makers of the 5071A
> ever made an optical version. I wonder what they are thinking
> now that someone else has done it.
> 
> Rick
> 
> On 3/17/2017 7:48 PM, cdel...@juno.com wrote:
> 
> > > 
> > Looks like Oscilloquartz is getting ready to sell this commercially!
> > Will give the 5071A a run for the money!
> > Reliability should go way up as:
> > -No electron multiplier
> > -No ionizer filament
> > -No state selection magnets
> > Also all the fiddley bits (laser diodes and photodetectors) are 
> > external
> > to the tube and can be easily updated as needed.
> > 
> > 
> > https://www.slideshare.net/ADVAOpticalNetworking/performance-results-of-a
> > n-optically-pumped-cesium-beam-clock
> > 
> > Cheers,
> > 
> > Corby
> > 
> > ___
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> > 
> > > 
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Re: [time-nuts] Optical Cesium or maybe Cesium "light"!

[Gregory Maxwell]

On Sat, Mar 18, 2017 at 2:48 AM,   wrote:
> Looks like Oscilloquartz is getting ready to sell this commercially!

http://www.chronos.co.uk/files/pdfs/itsf/2015/day2/1410_High_performance_optically-pumped_cesium_beam_clock-PBerthoud-Oscilloquartz.pdf

Two year old deck with a fair amount of overlap, though a few more
engineering diagrams.

Heres to hoping they fit it with an unreliable LCD backlight so
they'll be available as cosmetically defective cheap surplus in the
future. :)
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