Properly designating UTC time

Discussion in 'Ham Radio Discussions' started by N7BKV, Jun 10, 2019.

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  1. K6CPO

    K6CPO Ham Member QRZ Page

    All this talk of time zones in relation to UTC is irrelevant. UTC ("Zulu time" or Greenwich Mean Time-GMT) is the same for everyone around the globe at any one given moment. This is why it's used in international communications. It's only when using LOCAL time that the zones come into play. Rather than using a letter to designate a time zone, it's easier to use the difference between the local time and UTC. For instance, in California we would normally say we are in the -8 time zone but when we move to daylight saving time we become a -7. In other words take UTC and subtract the indicate number of hours to get the local zone time.

    For example, right now it's 2223 hours UTC. Subtracting the 7 hours gives 1523 hours local (or PDT, if you wish)
     
  2. KT1F

    KT1F Ham Member QRZ Page

    In computing when you need to deal with local time, the so called Time Zone Database is widely used.

    https://www.iana.org/time-zones
    https://en.wikipedia.org/wiki/Tz_database

    This contains the daylight saving rules. Here on the east coast, rather than setting my local time zone to EST or EDT, I'd set it to something like America/New_York. Then the system knows how to convert from UTC or a Unix timestamp to my local time throughout the year or any time in the foreseeable past or future. If the government changes the daylight saving rules and I keep my system updated then it will know about the change.

    It's a collaborative effort to keep it updated. It's interesting to read some of the archived mailing list here. https://mm.icann.org/pipermail/tz/
     
    Last edited: Jun 11, 2019
  3. W4IOA

    W4IOA Ham Member QRZ Page

    Analysis paralysis
     
  4. KA9Q

    KA9Q Ham Member QRZ Page

    I think it's simple readability. The colon isn't important when you show just hours and minutes, but it does make a difference when you're also showing seconds. I always try to show seconds on my computers if only to show that the display isn't frozen.
     
  5. W9RAC

    W9RAC Subscriber QRZ Page

    GMT is a time zone and UTC is a time standard, different. RAC
     
  6. KJ4VTH

    KJ4VTH Ham Member QRZ Page

    time out!

    [​IMG]
     
  7. W4EAE

    W4EAE Subscriber QRZ Page

    Sorry for my pedantry, but...

    0830 suggests 8.30h mathematically, or 8 hours and ~20 minutes.

    08:30 is not perfect, but it is more clearly 8 hours and 30 minutes.
     
  8. G3ZPF

    G3ZPF Subscriber QRZ Page

    "...GMT is a time zone and UTC is a time standard, different..."

    Most people use the terms GMT, UTC, and UT, as if they were different expressions for the same thing, but they represent different standards.

    "...is Ham world all it's own slippery convention?..."

    The more you look into it, the slippier the slope gets. http://www.g3zpf.raota.org/articles/QTR.pdf
     
  9. W4NNF

    W4NNF XML Subscriber QRZ Page

    Never used one in SAC...it was just..."Time hack! 2150!" ;)

    So that is how I roll. :)
     
  10. K4KYV

    K4KYV Subscriber QRZ Page

    I always SPELL the month with a two-letter digraph. I believe this is standard in some branches of the military.

    For the months, JA, FE, MR, AP, MY, JN, JL, AU, SE, OC, NO, DE

    To-day's date would be written as: 14JN19. The 1st of the month would be 01JN19. Always 6 characters, instantly recognisable, no ambiguity. I wish everyone used it.
     

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