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Interesting Find: Auto DST in GW-3000B

6879 Views 22 Replies 13 Participants Last post by  mikenbetts
Found something interesting in my new GW-3000B (Module 5121): at least in the USA, it sets Daylight Savings Time (DST) to "on" when it synchs within the four continental USA time zones.

Here's the situation: I'm in Arizona, where it's MST year-round (except for the Navajos).

1. Set my home city to Denver (DEN).
2. Set DST to off (the indicator says STD, meaning standard time).
3. Returned to normal mode, and everything is kosher.
4. Let the watch synch overnight.
5. Next morning, watch is an hour ahead, and when I display my home time zone, it still shows it as Denver, but with DST "on".
6. Checked the synch indicator, and it says "Y" (Yes, I synched).

So... I figured I made a mistake with the home time zone, so I tried it again. Very carefully following the manual.

Next morning, guess what? Denver is magically set to DST "on" again. Tried this two nights running, with the same results.

The GW-3000B has an undocumented auto-DST feature. Only thing that I could find supporting this in the manual was this cryptic entry: "As of November 2009, China does not use Daylight Savings Time (DST). If China does go to the Daylight Saving Time system in the future, some functions of this watch may no longer operate correctly." In other words, there is an automatic DST setting for certain time zones, and China is not currently one of them (implying that other zones, namely North America and maybe Europe, are).

I'm posting this for the benefit of others in non-DST locations (AZ, IN), who might otherwise be scratching their heads, thinking that they did something wrong by setting their watch to the correct time zone, overriding DST, and then finding the watch an hour off after a successful synch.

Personally, I'd rather Casio left well enough alone, and allowed an override of DST for every time zone, but there you have it. My fix for the thing, of course, is to simply set my home city to LAX for Summer, and DEN for Winter... oh how I wish they had an AZ zone on their watches. ;)
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What the watch does must be wrong.

It seems to me like you have discovered an error in the firmware of the watch and it would be worth the while contacting Casio.

The manufacturer has taken into account the fact that there are areas which do not observe DST.

For this reason there are intentionally three possible settings for DST: 1. AUTO (the DST will be driven by whatever the radio signal says), 2. OFF (the DST will be off; and whatever the signal says about DST will be ignored), 3. ON (the DST will be on, and whatever the signal says about DST will be ignored).

If you are sure you set your DST to OFF, but the watch is behaving as if it were AUTO, you should write to Casio as they have a mistake somewhere in their plans.

If you set your timezone "one zone back", this might be a solution for you to display correct time in the main timekeeping mode, but of course will affect the time shown for other time zones in the world time mode :(
Hi gaijin, thanks for your post.

ad 3. I realise now that my brain failed me when I was writing my last post, and that, really, the world time will be all right with this setting.
ad 2. I also realise (what I didn't know before) that there are moduls which do not have the independent DST setting, but still
ad 1. I thing it is wrong, although now I know that it was the intention; as it is about as 'simple' as having to set your watch everytime the time changes -- so people in the areas with no DST are losing the 'time is changing -- you don't have to' factor ;) although their government wanted them to have the opposit i.e. be the only ones in the area who do not suffer about the time being changed -- a bit paradoxical if you ask me :D
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