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.isan...@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 <att...@kinali.ch> wrote: > > > On Sat, 25 Dec 2021 15:27:51 -0800 > > Hal Murray <halmur...@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 > > _______________________________________________ > > time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe > send > > an email to time-nuts-le...@lists.febo.com > > To unsubscribe, go to and follow the instructions there. > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send > an email to time-nuts-le...@lists.febo.com > To unsubscribe, go to and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.