There are watches that can receive multiple longwave time signals, like Casio GShocks that cover 6 systems. They'll chose the best one based on what city you program.
I am currently wearing a talking watch that has four time settings: Pacific, Mountain, Central, and Eastern. It is supposed to receive an update every morning around 3am my time that keeps its time in sync. The fact that the watch is supposed to receive this update tells me that it is getting information from a satellite.
I'm going to come back to that in a moment because something odd has happened this week. First, though, regarding the use of standard and daylight saving time, because the watch has only the four settings for time zones in the United States, it assumes that everyone springs forward and falls back and behaves accordingly. I live in central Arizona, a state which, outside of some of the northeastern tribal lands, does not spring forward or fall back--it uses Mountain Standard time year round. So, what I have to do on the weekends of the time changes is change the time zone setting of the watch. During the summer, it's set to Pacific time and during the winter it's set to Mountain time.
Now back to the watch's daily update from satellite. I'm guessing the current operations in Iran may be involved. Since Monday, the watch has *not* updated its time listings at 3am each morning as it has done in the past. And, even if you try to force it manually to update itself, it will not do so. Again, I'm guessing that the satellite it is supposed to contact for that update is no longer available.
