
First Atomic Clock Wristwatch - Tomte
http://leapsecond.com/pages/atomic-bill/
======
Theodores
Reminds me of a highly accurate clock used in broadcasting. This clock sends
out a time signal around the building to various clocks on walls and
equipment, e.g. 'VT machines' (or whatever is used now).

I had the pleasure of adjusting this clock for GMT/BST twice a year. The great
thing about this clock was that it did not actually tell the time itself. One
would have to walk out of the machine room and through a couple of corridors,
up a flight of stairs and into a gallery to actually see the alleged time with
one's own eyes. All it had was a MODEM socket hidden in the back of a 19U
rack, with the wires in U.S. configuration rather than what we have in the
U.K.

So, to change the time you could 'conveniently' solder up a lead that would
actually connect to the box, telnet in, remembering to get the password right,
then set the time zone using the obscure command procedure provided.

This would be a simple enough task, however, there would be two of these
clocks and they would talk to each other. So changing the time on one would
not be good enough, the other would correct it or set it ahead/back by another
hour. For added convenience the other 'master' clock would be in an entirely
different part of the building and need to stay 'on' the whole time.

When it comes to extreme horology, I think that the most stupendously over-
the-top accurate timepieces should not actually be able to tell the time with
something as cheap and tacky as a display. If the time does have to be
displayed then it should be in UNIX epoch time as that is the most convenient
for all concerned.

~~~
stingraycharles
A bit off-topic, but this is one BBC Horizon documentary I enjoyed, "Do you
know what time is?"

[http://www.dailymotion.com/video/x18wcfo_horizon-2008-do-
you...](http://www.dailymotion.com/video/x18wcfo_horizon-2008-do-you-know-
what-time-it-is-ws-pdtv-xvid-mp3_lifestyle)

Basically, we, the human race, still have no clue at all what time is and why
it only moves forward.

~~~
brokecharlie
Even further off-topic and even more insightful is the Weekly Wipe' Moments of
Wonder on Time:

www.youtube.com/watch?v=NvpbW7JRu0Q

;)

~~~
stingraycharles
Are there any experts on the subject that can tell how accurate these
documentaries are? I find it fascinating, but am always sceptical about the
simplifications they might use.

~~~
danpat
I would highly recommend watching that Moments of Wonder mini documentary, it
will go some way towards answering your question.

------
sanxiyn
Also see this experiment from the same site:
[http://leapsecond.com/great2005/](http://leapsecond.com/great2005/)

Quote: "So, yes, not only do we live in a time when atomic clocks are
altimeters, but when relativity is child's play. It was the best extra 22
nanoseconds I've ever spent with the kids."

~~~
e12e
This got me thinking: How can you tell that two clocks are 22 nanoseconds
apart? I mean, it's not like you can look at a display or anything.

 _This is a bit of a rhetorical question, I 'm sure Google holds many answers
involving decaying isotopes or measuring laser pulses or something._

~~~
jloughry
_How can you tell that two clocks are 22 nanoseconds apart?_

If the clocks are in the same room and you have a fast oscilloscope at hand,
it's easy.

If the clocks are more than about 6 metres apart, it really is impossible.

~~~
dragonwriter
So, if you have a room that's got a dimension larger than 6 meters, and a fast
oscilloscope, you can have a situation in which it is both easy and
impossible?

~~~
jloughry
I get in trouble regularly with my wife because I've been trained my whole
life to think in a particular way, and that's not how other humans are wired:

    
    
        if (a) {
            b;
        }
        if (c) {
            d;
        }
    

versus

    
    
        if (a) {
            b;
        }
        else if (c) {
            d;
        }
    

She has mostly learned to put up with me by now, but the difference (how
programmers think) still comes out sometimes.

Edited to explain: programmers don't think exactly like other humans.

~~~
dragonwriter
Of course, in programming in the first case, "b" and "d" both happen when "a"
and "c" are both true in many languages, unless "b" is something like "return
e"

But, anyway, I was mostly joking -- its not like your meaning was at all
unclear.

------
cnvogel
For a little bit of context, leapsecond.com is the website of Tom Van Baak,
one of the "Time Nuts", people striving (sometimes: obsessed with) to maintain
precise clocks and oscillators, mostly for the fun of it.

Here's a recent talk of him, at the ARRL and TAPR Digital Communications
Conference, 2013.

[https://www.youtube.com/watch?v=MT2reYXPvGg](https://www.youtube.com/watch?v=MT2reYXPvGg)

Also interesting, the state of the art in amateur timekeeping (but already
2003):

[http://leapsecond.com/ptti2003/index.htm](http://leapsecond.com/ptti2003/index.htm)

...and clock powers of ten.

[http://leapsecond.com/ten/](http://leapsecond.com/ten/)

~~~
rootbear
Thanks for posting those! I came across the leapsecond site years ago and
enjoyed it but haven't been back in a while. If I wasn't already so over-
hobbied I'd probably be a time nut. My father is a ham radio operator and
always set the clocks in the house from the WWV broadcasts, thus establishing
in me at a young age an appreciation of accurate clocks.

------
deutronium
Haha, good for increasing your arm strength. There does seem to be some
slightly more portable ones:

[http://www.microsemi.com/products/timing-synchronization-
sys...](http://www.microsemi.com/products/timing-synchronization-
systems/csac#product-info)

Also you can get fairly cheap rubidium clocks from ebay that tend to output
around 10MHz for fairly cheap. They would be less accurate that the one he's
sporting however.

~~~
makomk
Yeah, someone's doing a Kickstarter for an atomic watch based on a similar
module but they seem to have sold out of them already:
[https://www.kickstarter.com/projects/846511652/the-worlds-
fi...](https://www.kickstarter.com/projects/846511652/the-worlds-first-true-
atomic-wristwatch-the-cesium)

~~~
shultays
Can someone explain me use of those atomic watches... with analog displays and
tuned by hand?

~~~
Sir_Cmpwn
The idea is not that it knows the time, but that it keeps time well. It just
has a very accurate measure of how long a second is.

------
rdl
Re the radio synchronized watches, it's annoying that most of them listen to
things like WWV, which is geographically limited.

The Seiko Astron is probably the best alternative, since GPS sync works over
the whole planet. Unfortunately, expensive. ([http://www.seiko-
astron.com/](http://www.seiko-astron.com/))

There are a lot of digital GPS watches (Garmin, Suunto, etc.), but some of
them (for some reason) don't sync the displayed watch time to GPS time.

~~~
jrockway
Watches actually listen to WWVB, not WWV. (WWV is on HF, WWVB is on LF.)

On a good propagation day, you can probably hear WWV around the world. If it
wasn't for other countries broadcasting _their_ time stations on the same
frequency, that is.

Ultimately, LF time synchronization is a good idea. It doesn't depend on
additional ionospheric information to get an accurate time transfer, since
signals do not travel through the ionosphere. HF signals take different routes
at different times of day, and GPS time transfer requires an accurate site
survey and accurate ionospheric delay constants.

------
Dave_Rosenthal
Since that post is quite old, I was surprised that this wasn't a reference to
Bathy's recent efforts to make a wristwatch out of a chip scale atomic clock
that is much closer to actual wristwatch scale (though still very large).

[http://www.ablogtowatch.com/bathys-hawaii-
cesium-133-atomic-...](http://www.ablogtowatch.com/bathys-hawaii-
cesium-133-atomic-wrist-watch-accurate-second-1000-years/)

------
daniel-cussen
There is now a 17cm3 atomic clock chip on the market for about $2300, well
under the price of a high-end watch. I'm surprised nobody's made a wristwatch
with that.

The chip: CSAC SA.45s.

~~~
danpat
Datasheet here:

[http://www.chronos.co.uk/files/pdfs/sym/sa.45s.pdf](http://www.chronos.co.uk/files/pdfs/sym/sa.45s.pdf)

120mW, 3.3V? Totally doable as a wristwatch.

~~~
sbierwagen

      120mW, 3.3V? Totally doable as a wristwatch.
    

I guess this is sarcasm? Typical quartz wristwatch power consumption is closer
to .01mW.

You could do it with a rechargeable battery, like a smartwatch, though you'd
be recharging it every night, like your phone.

~~~
danpat
Perhaps I should've said "wristwatch formfactor", you're right, battery
performance would not approach cheap digital watch, not by a long shot. But at
at 120mW, you'd be able to get a few hours out of it with a CR2032 cell, which
is better than useless. Garmin made GPS wrist units that up until recently
have done no better than this, although admittedly, there's probably more
utility in having a GPS on your wrist than an atomic clock.

Your could write "HOURS AND HOURS OF BATTERY LIFE!!" on the packaging.

~~~
sbierwagen
Yeah, but lithium coin cells are $5 each when your end user buys them at the
grocery store.

~~~
danpat
Good point, that totally kills the economics of this project.

------
Aardwolf
Shame that it's so huge!

I would love to have a small form factor real atomic clock wristwatch.

Then I could impress people like "your watch may have a touch screen and
smartphone integration, but, mine is ATOMIC!"

~~~
DEinspanjer
Well, I think all watches are made of atoms and hence ATOMIC. I think most
just don't intentionally include an atom of cesium, ask it to resonate, and
then measure the frequency. ;)

------
PhantomGremlin
The really sad thing is how the "old" HP was so cool but now it's gone.

They designed and built so many fantastic products, and then wrote amazingly
detailed articles about them in the Hewlett-Packard Journal.
[http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/hpjindex.html](http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/hpjindex.html)

------
davidgay
Rather less silly, actually an atomic watch and close to wristwatch size:
[http://www.ablogtowatch.com/bathys-hawaii-
cesium-133-atomic-...](http://www.ablogtowatch.com/bathys-hawaii-
cesium-133-atomic-wrist-watch-accurate-second-1000-years/)

edit: grammar

------
ajford
This story is tacked up on the wall inside the clock room at the Arecibo Radio
Observatory. The "Keeper of the Clocks" here eagerly awaits a true atomic
watch based off the CSAC SA.45s chip that @daniel-cussen mentioned.

~~~
DEinspanjer
How go the repairs there? I loved visiting the observatory and museum hall on
my first few trips to PR.

Did they manage to keep all or most of it open to the public or is it now
purely a science installation?

Edit: Ah, I found a link to the visitor's center (
[http://www.naic.edu/outreach/describe_fset.htm](http://www.naic.edu/outreach/describe_fset.htm)
). Happy to see it is still serving the public and looking forward to taking
my kids there next trip down.

------
akandiah
If you want something that would have an accuracy that's relatively close to
an atomic watch, get one that synchronizes its time using GPS.

~~~
Crito
Relatively close? What is this, horse shoes or hand grenades? I need
_precision_ dammit!

------
sdfjkl
Technically this is an underarm-watch, not a wristwatch. Imprecise terminology
is almost as bad as clock drift!

------
henrygrew
Who would wear that, seriously

~~~
BostX
Someone who needs that, seriously!

------
TomGullen
Chuck Norris' watch

------
roevhat
Where do I order one? I'm hooked!

------
LukeB_UK
I can't help but feel this is a little impractical.

~~~
cjfont
Perhaps a bit, but the boldness and style quickly make up for that.

------
Gmo
If the goal is to show that people upvote without looking at the link, then I
think it's quite successful.

------
therealmarv
This is fake. Do you see the power cable on the photos? They do not use
batteries on their photos!!! And I thought it is finally true ;)

~~~
phkamp
The HP5071 has built in rechargeable batteries.

