Daylight Savings and Radio Controlled Watches.

[Santa Clarita Len]

I am confused about how radio controlled watches actually change to daylight savings time. I have both analog and digital, the digital one was in a glass top jewelry box and did not change time but the analog one was 4" away and did change time. I removed the digital from the jewelry box ant the next night it changed time so I guess the signal was restricted.

My real question is does the analog watch just advance the hour hand or does it advance the minute hand 24 hours and the hour hand advances as a result? I guess the digital watch just advances the hour digit by one. Is there more than one radio signal sent out for different types of time pieces or just one signal and the time piece decides how to make the adjustment. Anyone know?

[LCHIEN]

there's obviously many ways to design a time keeping and display device.
You ask multiple questions, here's my understanding:

The time is only sent in a digital format, regardless if the display type is analog or digital.
Analog radio-controlled watches are really digital clocks with hand displays. While it is possible that you could have two motor controls and drive the hour and minute hands seperately, I have had two in my possession - one a clock movement module from Clockit and the other a Jergens clock. Both used a single motor with a traditional geared clock movement. So to advance the time on DST changing they each advanced an hour in the spring or 23-hours in the fall. It would take quite a few minutes for the latter; i think the minute had went around about twice per minute.

As for the synchronization, its not unusual for the synchronization to take place once a day. Again, its design dependent, but especially for watches with limited power, you would design a simple receiver and might only have it on part of the time to save power. The clock would run on its own crystal which would have a typical error of no more than a few seconds a day and not require continuous updating. Furthermore the radio uses longer waves which propogate much better at night. So a portable, power-limited design (e.g. a watch) that might update as infrequently as once a day or even every other day would work for most most users who would only notice in the case of a time change, as you did. I've owned several radio-controlled table clocks and even those had instructions that suggested it would take hours to update automatically.

[RAFlorida]

My understanding is that

the watch/clock is set to WWV frequency which is 10, 15 and 20 MHZ, (there's some other frequencies also, but these three are very commonly used). This signal containes all the information needed for radio-controlled time pieces to stay on the right time. For the U.S.of A., the signal comes from Fort Collins, Co.
Hope this helps