jimlux wrote in <cf4c5e3e-ba36-5285-3959-26e07252d...@earthlink.net>: |On 10/28/22 11:10 AM, Steffen Nurpmeso wrote: |> Steve Allen wrote in |> <20221028045813.ga20...@ucolick.org>: |>|On Thu 2022-10-27T19:25:01-0700 Steve Allen hath writ: |>|> Levine, Tavella, and Milton have an upcoming article for Metrologia |>|> on the issue of leap seconds in UTC |>|> |>|> https://iopscience.iop.org/article/10.1088/1681-7575/ac9da5b |>| |>|sorry, stray character appended to my cut and paste |>| |>|https://iopscience.iop.org/article/10.1088/1681-7575/ac9da5 |> |> That "increasing number of applications" all through the document |> makes me angry really. I find it astonishing to read that there |> are digital clocks that cannot display a second 60 and all that. | |The digital clock by my bedside, and a variety or other clocks that |don't have computers in them don't display second 60, nor do they handle |going from 58 to 00.
Yes. That is how it mostly is ever since. That is, i recall a leap event shown in the Tagesschau news of German TV, red colour on black from America .. Wall Street? That turned to 60. |The clocks in my various and sundry appliances also do not do this. | |One can argue, who cares - whether the oven turns on a second early or |late probably isn't a problem. That i would argue for most of these clocks myself. Even my laptop that synchronizes via SNTP through rdate -a with an always-on vserver that has NTP running, and which does /sbin/hwclock --systohc --update-drift shortly before each "echo mem > /sys/power/state" and before poweroff has to be adjusted anywhere from -0.372340 to -0.916331 seconds on a new-days's first sync. |But what about the enormous number of industrial process controllers - |almost all of which do not deal with leap seconds. At some point, sure, |they'll sync, either by hand, or over the network. And that's where it |starts to get sticky. | |Do you smear or jump? If you're running a system where seconds count - |radar is one example. A plane moves several hundred meters/second. If |you're tracking and sending position reports, do you transmit times in |UTC or TAI? | |There's the possibility of cooperative traffic avoidance for cars, |planes, and boats - The data is always late, so there's an element of |modeling taking position and velocity at time t=x-Nseconds and |propagating that forward to t=x. | |> This is just another outcome of the trivialization and |> superficialication all around. You need a reliable source of |> time, use TAI; or distribute the offset of UT1 and UTC |> permanently, best TAI, too. so that changes can be detected. NTP |> does still not do it, does it. (It is still not using DTLS but |> something else, too. My one cent (again).) You know how large |> these packets are? Now that even refrigerators and light bulbs go |> online (and letting aside the privacy issues), it is all there, at |> your fingertips. Sorry, i do not understand. | |It is precisely because there is a difference between UTC and TAI (or |GPS) that changes, and that there is no "universal" way to handle the |change that it is a problem. Mission critical systems will tend to |figure something out, but it might be different. | |I worked on SCaN Testbed [1] - a system that flew on ISS for a number of |years. This inconsistency of intepretation of time (UTC, GMT, GPST, TAI) |led us to implement a flight rule "Turn off the power 1 hour before the |leap second and turn it on 1 hour after". That was easier than trying |to get everyone on the same page (everyone is a remarkably large crowd - |experiment PIs, test controllers and engineers, payload operators, ISS |controllers, ISS internal data bus time distribution (Broadcast |Ancillary Data on MIL-STD-1553), not to mention the entire pipeline of |data links up to and back down all the way to the ops center. How terrible! |[1]R. C. Reinhart, T. J. Kacpura, S. K. Johnson and J. P. Lux, "NASA's |space communications and navigation test bed aboard the international |space station," in IEEE Aerospace and Electronic Systems Magazine, vol. |28, no. 4, pp. 4-15, April 2013, doi: 10.1109/MAES.2013.6506824. That is grazy. Needs a sign-in for full reading. Well i do not know obviously. I would emit a steady thing and an offset to human time, i think that i already said in the first message to this list, about NTP, then. But i would not make the human time scale that steady thing. ... --steffen | |Der Kragenbaer, The moon bear, |der holt sich munter he cheerfully and one by one |einen nach dem anderen runter wa.ks himself off |(By Robert Gernhardt) _______________________________________________ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
