[6th APR 2019] Any UTC-users of GPS systems: Prepare for "GPS Week # Rollover Event" WNRO (sim. to Y2K glitch?)

IVI on 12/03/2019 - 22:28
Last edited 12/03/2019 - 23:02

Dunno if Garmin, etc. (or designers
of the satellites, that they depend on)
were "sloppy" …or just wanted us all
to feel, that "we need 'em" (as for the
Y2K glitch)…

(My guess is, that - in order to save
a few bits of (then) costly RAM, they
counted weeks in a 10-bit field for a
19-year week-cycle (soon to be all of
13-bits for 157-year week-cycle, at a
cost of multiple-Billions of $$.

Meanwhile, more recent GPS satellite-
systems - from EU, CN, RU, etc. - don't
seem to have that issue, per reports.)

But - If you, or some1 you know - uses
GPS to derive UTC (Grenwich Mean Time
GMT or Zulu) times check it out BEFORE:

  • Date of Interest = 6th April 2019 <= NEXT MONTH

(One Google hit referred to Aviation,
suggesting it could be good Not to
be flying around or on that date…?)

Have a read & decide for yourself:

Garmin:
+ https://support.garmin.com/ms-MY/?faq=zWQY6Z2kFiAuY9kDnDBgZ6

Maker of Indoor GPS-Repeaters:
+ https://www.gps-repeaters.com/blog/gps-week-number-rollover-…

US Homeland Security alert:
+ https://ics-cert.us-cert.gov/sites/default/files/documents/M…

Comments? Explanations? Suggestions?
And / Or: Horror Stories (fr Y2K even)? :~)

Electrical & Electronics

Comments

  • ozhunter on 12/03/2019 - 22:44
    +2

    Thanks

    • IVI on 12/03/2019 - 22:47
      -1

      "Hey, 'at's a-OK, we senda bill!" :Chico Marx

  • Davo1111 on 12/03/2019 - 22:52
    +5

    google "word wrap"

  • spackbace on 12/03/2019 - 23:06
    +5

    That's
    Good
    To
    Know

  • Diji1 on 12/03/2019 - 23:08
    +7

    What?

  • [Deactivated] on 12/03/2019 - 23:08
    -2

    I hope it corrupts Pokemon Go saves.

  • alvian on 13/03/2019 - 03:23
    +2

    Is this supposed to be a poem?

  • whooah1979 on 13/03/2019 - 05:57
    +8

    Why is it always so difficult to understand IVI posts?

    • RockyRaccoon on 13/03/2019 - 06:28

      Probably channeling Dustin Hoffman……

  • neo on 13/03/2019 - 08:33

    April Fools

  • abb on 13/03/2019 - 09:55

    This is a fairly standard calendar rollover scenario, nothing to worry about. GPS has been around for about 40 years so it's not the first time it's happened. Only a naively-implemented GPS receiver would suffer any problems, the problem would only be that the date/time is indicated wrong, and a home-made one is unlikely to be running anything of importance.

    Each frame contains (in subframe 1) the 10 least significant bits of the corresponding GPS week number.[13] Note that each frame is entirely within one GPS week because GPS frames do not cross GPS week boundaries.[14] Since rollover occurs every 1,024 GPS weeks (approximately every 19.6 years; 1,024 is 210), a receiver that computes current calendar dates needs to deduce the upper week number bits or obtain them from a different source. One possible method is for the receiver to save its current date in memory when shut down, and when powered on, assume that the newly decoded truncated week number corresponds to the period of 1,024 weeks that starts at the last saved date. This method correctly deduces the full week number if the receiver is never allowed to remain shut down (or without a time and position fix) for more than 1,024 weeks (~19.6 years).

    https://en.wikipedia.org/wiki/GPS_signals

  • Hithere on 13/03/2019 - 09:57

    So, turning it off and then on again will fix it?

    • trongy on 13/03/2019 - 11:43

      No.

      However only really old or crappy GPS devices will be affected. If the GPS has a way to manually enter the date in it's setup menu or a way to learn the date from a different source (e.g. an internet connection) then it should be fine.

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