[time-nuts] Re: Where do people get the time?

[Raven L]

For what it's worth, my google pixel on AT&T's network in the US is almost
always at least a second off UTC - at the moment, it shows -1.77s (courtesy
of the ClockSync app). Seeing it within 0.5s is actually mysteriously rare.

On Mon, Dec 27, 2021, 2:16 PM Adam Space <time.isanapp at gmail.com> wrote:

> As a younger person I appreciate this write-up. It is interesting to see
> the progression. Nowadays, phones are synchronized to within a second
> easily, and probably within 10ms at least once per day (this is what I
> suspect from occasionally checking the offset on my phone). With computers
> too, I would bet that most come out of the box with some sort of NTP setup
> that at the very least keeps them within a few seconds, depending on how
> often the default polling interval is. The idea of having to go to great
> lengths to get access to an accurate time signal seems foreign today, but
> it's interesting hearing about that being the case in the past.
>
> On Sat, Dec 25, 2021 at 8:07 PM Attila Kinali <attila at kinali.ch> wrote:
>
> > On Sat, 25 Dec 2021 15:27:51 -0800
> > Hal Murray <halmurray at sonic.net> wrote:
> >
> > > How good are cell phones?  I remember comments about them being way
> > off.  But
> > > that was a long time ago.
> >
> > Cellphone network time distribution is something rather new
> > and didn't exist until EDGE (or was it HSDPA?) came along.
> > But once it was available, it was "good enough", i.e. the
> > time offset was low enough to be not perceivable (~100ms).
> > At least in Europe.
> >
> > I know from other countries, that back in 2005, network time
> > was off by a few minutes. This has probably improved now, because
> > UMTS requires the cells to be synchronized to UTC to within
> > a few 10s of µs. (I don't remember the details, Magnus can
> > provide a more accurate picture) And by already having accurate
> > time in the network, providing that to the cellphones is easy
> > and the obvious way to go about.
> >
> >
> > > If I was doing it now, I would probably setup one of the battery
> powered
> > > clocks that listens to WWVB.  When were they first widely available?
> >
> > Hmm... Let me give you a quick history of how time aquisition
> > evolved through the eyes of a fledgling time-nut :-)
> >
> > Disclaimer: This is how I experienced things as I grew up in
> > Switzerland. It was probably quite similar throughout western
> > Europe, but I didn't travel enough until early/mid 90s to say
> > anything beyond the countries I visited regularly. Not to
> > mention that a toddler who can't read a watch wasn't much
> > interested in how to get accurate time in the first place...
> > That said, Swiss were and still are quite a bit more obsessed
> > with time than the rest of Europe. So my view might be a bit
> > skewed.
> >
> > In the 80s virtually all watches and clocks were quartz movements.
> > I.e. they kept time accurately enough for most things. There were
> > still some mechanical watches around, but they were mostly a
> > thing of the past and kind of a fashion statement... Or a watch
> > gifted by a relative decades ago. Most people set their watches
> > at least every 6 months, when dailight saving switched. I had
> > (and lost) a Swatch Flick Flak (
> > https://www.newlyswissed.com/wp-content/uploads/2015/08/Flik-Flak.jpg ),
> > two Pop Swatch ( https://www.uhrenkosmos.com/30-jahre-pop-swatch/ )
> > and two Tissot Two-timer (pretty much this model
> >
> https://watchcharts.com/listing/1084976/tissot-twotimer-timer-analog-digital-watch
> > ).
> > as my watches as a kid during kindergarten and elementary school.
> > The Tissot I used until I broke its wristband holder a week before
> > I graduated from high-school, which had a pretty deep gouge in the
> > glass through the whole watch face when I fell on some gravel path
> > in 4th grade.
> >
> > None of these watches were special for a child in Switzerland.
> > Even the Tissot Two-timer, which was IIRC CHF 80-100 back in
> > the late 80s (probably around 200 USD in today's money), was a
> > relatively common watch to have as an elementary/middle school
> > student. And even a first grade student was expected to have
> > some form of a watch, either on his wrist or in his pocket.
> > And that, even though there was a clock somewhere in sight virtually
> > everywhere in Switzerland  as there were plenty of watch/clock shops
> > and a lot of stores had a clock somewhere around the entrance.
> >
> > The way to get time was usually TV and radio broadcast or church
> > bell towers. One popular way was to adjust to the beep at the
> > start of the news, which was always scheduled at fixed time
> > (usually the start of the hour).
> >
> > But using Teletext ( https://en.wikipedia.org/wiki/Teletext )
> > was more common, whenever a TV was available, as it offered to
> > have time without waiting for a special program and could be
> > read with sub-seconds accuracy. What was a bit weird, now that
> > I think back, is that different TV stations had slightly
> > different times. Usually just a few seconds, but enough to
> > be noticable. I usually set my watch whenever I noticed that
> > it was off more than 30-60 seconds (usually because I would
> > start missing the bus). Which was, if I remember correctly,
> > every 3-4 months with the Tissot.
> >
> > The clocks of churches and schools were, in the 80s, already
> > synched up to HBG or DCF77, though I did not know that back then.
> > I just saw the big blinkenlights that would control the clocks
> > and would wonder why they were so big. :-)
> >
> > In the late 80s, DCF77 alarm clocks became cheap and very common.
> > And we started using them as a quick reference instead of the TV.
> > They also had the advantage of always showing the time, which made
> > checking the accuracy of one's watch kind of an automatic and
> > regularly performed movement. Their range was quite impressive too.
> > I once took one to Turkey and it would still sync up during the
> > night. (I completely forgot that I left it there with a relative
> > until it turned up a few years ago, still working).
> >
> > In the late 90s, early 2000s, the internet became more ubiquitous
> > and people started to use NTP to sync their computers and then
> > set their watches according to their computers. At least those
> > of us who were using Unix/Linux. It would take another couple
> > of years, until Windows would offer something similar out of
> > the box, though it would take IIRC until Windows Vista for it
> > to be accurate for better than 10 seconds (which lead to interesting
> > effects when using concurent document editing through Active
> > Directory). Also around the same time, everyone and their dog started
> > to have a cell phone. While at first one had to manualy set the
> > time (the same way as a watch), at some point in the first half
> > of the 2000s, the cellphone network started to provide time.
> >
> > Today, for most people, their cellphone is the thing that provides
> > them with accurate time to which they set ther watches and clocks.
> >
> > For me, my main clock source is NTP, for the most part. At least
> > for everything that is networked. I do have a GPSDO that provides
> > me with an accurate PPS for my time-nutty needs, but that is only
> > used within my home network and for measurement. I set my watches
> > twice a year, when I have to adjust them for daylight savings,
> > by which time they are usually off by less than 10s. (Modern
> > quartz watches are amazing!)
> >
> >                         Attila Kinali
> >
> > --
> > The driving force behind research is the question: "Why?"
> > There are things we don't understand and things we always
> > wonder about. And that's why we do research.
> >                 -- Kobayashi Makoto
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