Change the timezone on the computer that's running the simulator

Lol, I figured this is the way, thanks for confirming there's no setting hidden in the simulator :) 

Has anyone tried testing the timezone IRL in your app? During an activity - crossing a time zone boundary and observing the behavior? Curious how frequently and how accurately Garmin devices respond. I know my phone does a great job of announcing state line crossings and timezone crossings. But I haven't tried that with my Garmin data fields.

This is not exactly crossing a border and thus in theory stepping into another timezone, but you can easily test this: start an activity, then change the timezone setting in your phone and sync from Garmin Connect (while still in the activity)

In my DF I display the time and it's updated immediately

This is not exactly crossing a border and thus in theory stepping into another timezone, but you can easily test this: start an activity, then change the timezone setting in your phone and sync from Garmin Connect (while still in the activity)

In my DF I display the time and it's updated immediately.

But I doubt that even a device with maps would know to automatically set timezone as you cross the border. I think what's more likely is that if and when your phone would connect to a provider from the new country, then it would switch the timezone of the phone (if set to auto), but even then you would need to manually sync the watch.

DaveBrillhart said:

Has anyone tried testing the timezone IRL in your app? During an activity - crossing a time zone boundary and observing the behavior?

flocsy🤠 said:

But I doubt that even a device with maps would know to automatically set timezone as you cross the border. I think what's more likely is that if and when your phone would connect to a provider from the new country, then it would switch the timezone of the phone (if set to auto), but even then you would need to manually sync the watch.

TL;DR Garmin devices *also* use GPS to determine the time *and* time zone. Syncing with your phone isn't the only way it happens.

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So actually, in general, all that would be necessary for the time zone to be updated is to get a GPS fix after you cross the border (you could open an activity which has GPS enabled or you could use the menu item in the system time settings labelled "Sync with GPS" or whatever). The standard advice of getting a GPS fix if your device time is wrong also applies to the case when the time zone changes.

Since DaveBrillhart was talking about behaviour during a GPS activity, his question was indeed relevant and the device should indeed automatically change the time / time zone during a GPS activity if you cross a time zone boundary (unless Garmin had some logic to not do this while the activity timer is running or something, which is doubtful). I haven't done this myself, so I have no idea how quickly this would happen.

And on a historical note, older watches did not support setting the time / time zone from a paired watch at all. (This was a source of complaints, so I'm not surprised Garmin added the feature eventually.)

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I would like to point out that Garmin devices can be used without a paired phone, and auto time / timezones still work. If you travel to another timezone and get a GPS fix, the time will automatically change on your Garmin device (to match the timezone that you are in). This has been discussed in the forums previously, more than once. But Garmin also says so explicitly:

https://www8.garmin.com/manuals-apac/webhelp/venusq/EN-SG/GUID-8F4D860E-2D7D-4B70-82D4-5C13865E4985-8266.html 

Syncing the Time with GPS

Each time you turn on the device and acquire satellites, the device automatically detects your time zones and the current time of day. You can also manually sync the time with GPS when you change time zones, and to update for daylight saving time.

Garmin devices ofc have a timezone database full of timezone definitions (including summertime / daylight savings time rules) - this database is updated from time to time (as seen in Garmin Express). And this database must include GPS coordinates for the various zones. Not only would this be necessary for timezone determination based on GPS, but it would also be necessary for LocalMoment to work (which gives you time and timezone information based on a specified location). I'm surprised you wouldn't have picked up on that, since you have asked about LocalMoment in the past.

I also don't know why you would imply that mapping information would be necessary (or expected) to have timezone auto-determined from location. Maps are huge - there's gigs of data - and the timezone DB is probably a few hundred KB. Even old watches (or non-mapping / non-music watches) with tiny amounts of storage support automatic timezone by GPS.

What newer users of garmin devices probably miss is that these devices have a long history of working without any connected phone. (I've "only" been using Garmin watches for ~10 years, and I picked up on this. Maybe it's because I almost never run with a phone.)

In general I wouldn't assume that any mission-critical functionality, like automatic time / time zones, requires a connected phone.

I know what is in the TZ updates in servers. It's small data compared to what you would need to determine your timezone based on location. Especially when you're not sailing on open seas, where the timezone borders are more or less straight lines. When the timezone borders are on land, they almost always follow country borders which follow in most places natural features. So having an accurate DB for this is not that simple IMHO. This means that most probably if you are close to the border between 2 timezones, then it'll not be precise.

To prove my point (that it is not an easy task) look at his map: https://www.timeanddate.com/time/map/ then look at a map close to countries borders in Europe or Africa and you'll see that if you would use this map and you would be in 10 km radius from the actual border (or maybe even more in some places) you could pretty much randomly be in one or the other timezone.

I'm not saying that Garmin has any problems, because the only way I crossed timezones so far was by airplane, where regretably there's no GPS reception even if you sit next to the window, so the only chance to test it [for me] is on the airport after you land, and that is in the middle of the timezone, so even if the DB would be a 1MB gif file, like the above, it would still work great for this case. Maybe they use 10MB map data or 100MB. I'll switch timezone this Friday, I'll try to remember not to enable the Bluetooth when I land and test it. I never thought there will be a time when landing with a low-cost airline where you need to walk into the terminal will be an advantage :) 

I guess this precision would be more than good enough for 95% of the people. but I wouldn't be surprised if there are some users who live close to a border and if they set it to auto timezone, then they'll jump to the other zone multiple times a day, even though they never left their country, so I'd guess that even Garmin would recommend to these people to set the tz manually.

Here's a much better map, but of course if someone lives in a small village near the Portuguese-Spanish or Polish-Ukrainian border, then it won't necessarily help: upload.wikimedia.org/.../World_Time_Zones_Map.png

Ok:

- Explain how LocalMoment would work without a phone connection

(LocalMoment takes a location (gps coords) as input and gives you local time with TZ info at that location)

By your argument, LocalMoment must be useless. Which is interesting, since you were the one who previously argued Time.now() should return LocalMoment.

- Explain why Garmin's manual says that time and time zone are both automatically determined by GPS. Note that real life users have reported this over the years too.

(I think someone posted about crossing time zones on a cruise ship or something)

- Explain how it ever worked in the past, when time (and presumably time zone) were not set from phone sync (there are many old complaints about time not syncing with a phone, and the responses all say to get a gps fix)

Unless the manual and past forum users are all lying to you.

And my point about maps is that mapping data is completely separate from the TZ stuff. Garmin doesn't need 1 byte of maps or 10 GB of maps to figure out time zone from location, they have done it in the past on watches with tiny storage and no maps. So the thing about maps is a total red herring.