Daylight Saving Time and Casio RCs
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  1. #1
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    Daylight Saving Time and Casio RCs

    I'm in Central Time Zone of USA (CST = UTC-6, CDT = UTC-5). Last Sunday March 9, 2014 was the "spring forward" leg of DST at 2:00am. Some of my non-Casio RCs exhibited some bizarre behavior, advancing 1 hour well BEFORE 2:00am Sunday.

    Casio manuals say their RC watches will automatically make up to SIX attempts to obtain the radio synch from Ft Collins, Colorado, beginning at midnight and every hour thereafter until 5:00am. The first successful "GET" cancels the all the remaining attempts for that day. Since my location is such that almost all first attempts at radio synch are successful, I can assume the Saturday night/Sunday morning midnight "GET" worked and subsequent early Sunday morning attempts were cancelled. But the cancelled Sunday morning 2:00am "GET" should be the one with the DST change. So, with the Casios, wouldn't they synch to the midnight "GET" and thereafter report CST for 24 hours (i.e. ALL Sunday) until the following day's "GET" finally updated the watches to CDT?

    So, did my (and your) Casio units miss the DST changeover for almost a complete day due to their programming? I presume they did, but I did NOT verify for myself that they misreported the DST changeover for a day.

    Thanks in advance for any illumination.
    Last edited by tyrenfroe; March 13th, 2014 at 04:43.

  2. #2
    Member Mike K's Avatar
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    Re: Daylight Saving Time and Casio RCs

    Quote Originally Posted by tyrenfroe View Post
    I'm in Central Time Zone of USA (CST = UTC-6, CDT = UTC-5). Last Sunday March 9, 2014 was the "spring forward" leg of DST at 2:00am. Some of my non-Casio RCs exhibited some bizarre behavior, advancing 1 hour well BEFORE 2:00am Sunday.
    I'm in the Eastern time zone, and all of the Casio atomic watches that I glanced at moments after midnight were already displaying "1:05 AM," so they "sprang forward" as soon as they received the signal at midnight.

    I'm not certain how WWVB is using the "DST in effect" "flag" these days -- I thought I read where there used to be a "pre-flag" a day in advance -- but I can live with my solar/atomics being wrong for one hour a year.

    Quote Originally Posted by tyrenfroe View Post
    Casio manuals say their RC watches will automatically make up to SIX attempts to obtain the radio synch from Ft Collins, Colorado, beginning at midnight and every hour thereafter until 5:00am. The first successful "GET" cancels the all the remaining attempts for that day.
    The newer Casio atomic watches do this -- I won't confuse things with a detailed explanation of how goofy the "old" MTG-900 and similar versions are, but the new system seems to be better for a lot of people.

    Quote Originally Posted by tyrenfroe View Post
    Since my location is such that almost all first attempts at radio synch are successful, I can assume the Saturday night/Sunday morning midnight "GET" worked and subsequent early Sunday morning attempts were cancelled. But the cancelled Sunday morning 2:00am "GET" should be the one with the DST change. So, with the Casios, wouldn't they synch to the midnight "GET" and thereafter report CST for 24 hours (i.e. ALL Sunday) until the following day's "GET" finally updated the watches to CDT?

    So, did my (and your) Casio units miss the DST changeover for almost a complete day due to their programming? I presume they did, but I did NOT verify for myself that they misreported the DST changeover for a day.
    As mentioned above, and possibly BECAUSE OF the way newer Casio atomics (and perhaps other watches) work with that "grab one signal, don't try again" feature, it appears that WWVB's "switch to DST" signal starts long before the "official" time switch at 2 AM Eastern time.

    That allows Eastern time zone watches (and then all the rest of the watches across the country) to receive the "switch to DST" signal at midnight local time.

    One hour fast for one hour is probably better than one hour behind for most of the following day!

  3. #3
    Member yankeexpress's Avatar
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    Re: Daylight Saving Time and Casio RCs

    It is WWV fault. They triggered the watches to DST early, just after midnight.

    WWV (radio station) - Wikipedia, the free encyclopedia

    Check out :57 in the diagram. It sets on/off DST by radio.

    Last edited by yankeexpress; March 13th, 2014 at 06:33.
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  5. #4
    Member Mike K's Avatar
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    Re: Daylight Saving Time and Casio RCs

    Quote Originally Posted by yankeexpress View Post
    It is WWV fault. They triggered the watches to DST early, just after midnight.
    With the way new Casio watches work, though, how else could they do it?

    If they changed the signal at 11:59 PM Denver time, which would be 1:59 AM Eastern time (and just in time for the "correct moment of time change" for the Eastern time zone), all of the (modern) G-Shocks in the Eastern and Central time zones would have already gotten the signal and stopped receiving for the night, so they'd be wrong when people got out of bed on Sunday morning.

    ...which is exactly the scenario the OP assumed was the case!

    Lucky for us that he was in fact wrong, and I'm glad enough of us night owls saw our G's switch a little early.

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    Re: Daylight Saving Time and Casio RCs

    Good info. DrD over on Seiko/Citizen found some more info that brings in :58 as well as :57 and explains how they're to be used together in DST changeovers. Check it out.


    DrD found this on Wikipedia.
    The DST status bits indicate United States daylight saving time rules. The bits are updated daily during the minute starting at 00:00 UTC. The first DST bit, transmitted at 57 seconds past the minute, changes at the beginning of the UTC day that DST comes into effect or ends. The other DST bit, at second 58, changes 24 hours later (after the DST change). Therefore, if the DST bits differ, DST is changing at 02:00 local time during the current UTC day. Before the next 02:00 local time after that, the bits will be the same.
    Each change in the DST bits will first be received in the mainland United States between 16:00 (PST) and 20:00 (EDT), depending on the local time zone and on whether DST is about to begin or end. A receiver in the Eastern time zone (UTC−5) must therefore correctly receive the "DST is changing" indication within a seven-hour period before DST begins, and six hours before DST ends, if it is to change the local time display at the correct time. Receivers in the Central, Mountain, and Pacific time zones have one, two, and three more hours of advance notice, respectively. It is up to the receiving clock to apply the change at the next 02:00 local time if it notices the bits differ. If the receiving clock happens not to receive an update between 00:00 UTC and 02:00 local time the day of the change, it should apply the DST change on the next update after that.


    I figure it's just lazy programming that results in the watch/clock behavior I observed. Instead of writing a few more lines of code to properly handle the DST changeover, the program simply monitor the change bit. If DST indicated, the watch advances one hour immediately. If return to standard time indicated, watch goes back an hour, also immediately. It's always the software...
    Last edited by tyrenfroe; March 13th, 2014 at 06:58.
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  7. #6
    Member Mike K's Avatar
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    Re: Daylight Saving Time and Casio RCs

    Quote Originally Posted by tyrenfroe View Post
    I figure it's just lazy programming that results in the watch/clock behavior I observed. Instead of writing a few more lines of code to properly handle the DST changeover, the program simply monitor the change bit. If DST indicated, the watch advances one hour immediately. If return to standard time indicated, watch goes back an hour, also immediately. It's always the software...
    The "software" in the watch (apparently, it's actually "firmware") needs to work correctly with the signal(s) from the radio tower. I can't help but wonder if the WWVB signal has changed in the last 10 years, since as mentioned above, a signal that might have worked 10 years ago might not have worked with newer atomic G's.

    I said that I wouldn't get into the way the early Casio solar/atomics worked, but I'm wearing my MTG-900 now and verified the behavior.

    The firmware in this one (and presumably some other models from the same era) isn't as well-written, IMHO. While new watches attempt to receive five or six times, every hour starting at midnight and then stopping once they synch, the MTG-900 tries to receive at 2 AM, 3 AM, 4 AM, and 5 AM whether or not it's synched that night!

    This one synched at 2:04 AM and now at 3:00, the display went blank again as it tried to do it again. For most of the world that's asleep at 3 AM, it's not a problem, but that feature could be better on the newer versions -- and it is. I'd rather have a watch that was off by one hour FOR one hour once a year than have a watch that tries to go through a redundant process three times a night, 365 days a year.

    They probably could program new atomics to recognize the "DST on or off" signal and THEN wait until 2:00 AM local time to apply the time change, but like so much else in the world, it's probably a matter of diminishing returns. What they have now works fairly well -- MOST people probably woke up Sunday morning and said "hey, cool, my watch sprang ahead on its own as advertised" and went on with their day. Is it really worth [amount of money] to perfect the process to make [relatively small number of people] happy about HOW their watch accomplished that feat?

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    Re: Daylight Saving Time and Casio RCs

    Wow! The early RC DST programming was TRULY pathetic. So it's a big improvement from then to now - from pathetic all the way to just feeble.

    I guess it's like they say: if you want decent software (firmware is just embedded software), you have to have it written in the USA. You see the same thing with NAV/entertainment/climate control systems in cars: American cars have MUCH better system usability and functionality than those developed by either Asian or European carmakers. (The rest of the American car is a different story, unfortunately.)

    I wish the RC watchmakers would get this DST thing right. There's really no excuse for such accurate instruments with demonstrated access to correct information to ignore that information and thus give up their claim to fame for ANY length of time at all. GET WITH IT, CASIO!

  9. #8
    Member Mike K's Avatar
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    Re: Daylight Saving Time and Casio RCs

    Quote Originally Posted by tyrenfroe View Post
    I wish the RC watchmakers would get this DST thing right. There's really no excuse for such accurate instruments with demonstrated access to correct information to ignore that information and thus give up their claim to fame for ANY length of time at all. GET WITH IT, CASIO!
    Wow -- truly can't tell if serious.

    If so, the "excuse" is that there are way too many variables, and too many cooks in the proverbial kitchen.

    We five different governments around the world sending out radio signals from six different antennas, which have to work properly with at least two different versions of Casio software along with who knows HOW many versions from other watchmakers?

    If Casio comes up with a newer, better way to do it, they have to make sure that it doesn't interfere with the "old" versions, or they'll anger a lot of existing customers.

    "Hey, we've found a better way to make this work! Bad news: your relatively new watch won't work with the new system, so you'll have to live with it or buy a new one. Ooops."

    How would YOU like to find out that all of your current atomic G's are now effectively obsolete? Oh, sure, they'd still be accurate to +/- 15 second a month, and MIGHT still update nightly, but you'd be back to switching them all on and off DST twice a year like a regular watch. In a truly perfect world, Casio could send us all replacement watches for free, but that isn't going to happen!

    Of course, Casio might also have to convince all the other watch manufacturers that their way is better, and that THEY need to switch as well, in case they all need to convince five government agencies to change their signal -- again. (Does anybody else remember reading something here about WWVB's "pre-DST signal" the day before time changes? Now all I can find mention of is a "one hour warning.")

    The funny thing is, I'm a "watch guy" -- at midnight I was looking at my watches and I have NO IDEA when my new cellphone changed its clock. For all I know, there are people on phone forums complaining about the same minor problem.

    Very few people are so obsessed with time that they stayed up until 2:00 AM to move the clocks forward at the appointed hour, and very few people really care exactly when their atomic watches "leaped forward."

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    Re: Daylight Saving Time and Casio RCs

    Quote Originally Posted by Mike K View Post
    Wow -- truly can't tell if serious.

    If so, the "excuse" is that there are way too many variables, and too many cooks in the proverbial kitchen.

    We five different governments around the world sending out radio signals from six different antennas, which have to work properly with at least two different versions of Casio software along with who knows HOW many versions from other watchmakers?

    If Casio comes up with a newer, better way to do it, they have to make sure that it doesn't interfere with the "old" versions, or they'll anger a lot of existing customers.

    "Hey, we've found a better way to make this work! Bad news: your relatively new watch won't work with the new system, so you'll have to live with it or buy a new one. Ooops."

    How would YOU like to find out that all of your current atomic G's are now effectively obsolete? Oh, sure, they'd still be accurate to +/- 15 second a month, and MIGHT still update nightly, but you'd be back to switching them all on and off DST twice a year like a regular watch. In a truly perfect world, Casio could send us all replacement watches for free, but that isn't going to happen!

    Of course, Casio might also have to convince all the other watch manufacturers that their way is better, and that THEY need to switch as well, in case they all need to convince five government agencies to change their signal -- again. (Does anybody else remember reading something here about WWVB's "pre-DST signal" the day before time changes? Now all I can find mention of is a "one hour warning.")

    The funny thing is, I'm a "watch guy" -- at midnight I was looking at my watches and I have NO IDEA when my new cellphone changed its clock. For all I know, there are people on phone forums complaining about the same minor problem.

    Very few people are so obsessed with time that they stayed up until 2:00 AM to move the clocks forward at the appointed hour, and very few people really care exactly when their atomic watches "leaped forward."

    Funny you should mention cellphones. If Apple or Samsung operated according to your principles, we'd still be clunking along with phones the literal size of BRICKS! Apple doesn't give a damn whether Siri causes everyone that paid full retail for a 3s to sob uncontrollably. The trend is ALWAYS toward greater capability for lower cost and the price to be paid is obsolescence of older models. We all accept this; the dilemma of the "early adopter" is a well-know facet of technology's "creative destruction". For an alternative view of progress, consult wiki for "Luddite." As far as programming to multiple variables, your cellphone example again provides the model. Consider those who successfully write apps to run (more or less perfectly) on all the flavors of iPhones (several) and all the flavors of Androids (several hundred/thousand?). You don't hear "no can do" from the coders, just "when's the new version coming" from users. Get with the program(ming), Mike.

    P.S. Not really about what happens at 2am, as I pointed out in my original post. My wall clock did its DST update at 7pm Saturday night! My Citizen watch updated at around 10pm Saturday night. If my DVR and cellphone were as stupid as my clock and my watches, my recorded programs would go MIA twice a year, and who knows how many texts, calls, and messages would be forever lost in the ether? GET WITH IT, CASIO!

  11. #10
    Member Mike K's Avatar
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    Re: Daylight Saving Time and Casio RCs

    Quote Originally Posted by tyrenfroe View Post
    Funny you should mention cellphones. If Apple or Samsung operated according to your principles, we'd still be clunking along with phones the literal size of BRICKS!
    The difference is that Apple and Samsung aren't using signals maintained and broadcast by the governments of five different countries!

    I really don't know that much about cellphones, but does Apple's changes with their phones directly affect the electronic performance of Samsung's phones? Last I'd heard, no. (If they COULD sabotage each other's phones with new releases, we'd have a whole new definition of "phone wars." )

    IF Casio (or Seiko or whoever) wanted to build a secondary "atomic clock radio tower" in each geographical location they currently serve, you might have a point, but for whatever reason they can't, won't, or don't find it economically feasible to do so -- which means they're stuck using WWVB's signal here in the US.

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