As we know, the “springing forward” of clocks for Daylight Saving Time happens at about 2AM. This “radio controlled” wristwatch does the DST adjustments automatically. I happened to be awake when it happened just now, and you can see a video recording of the automatic adjustment carried out by this wristwatch.
By way of background, this wristwatch is solar powered — the face of the watch is a solar panel and it charges up a rechargeable battery inside the watch. This watch also contains an HF (high frequency) radio receiver to pick up a government time standard broadcast once every day. (I first blogged about this particular wristwatch about six years ago – blog article.) Depending on the geographic location of the watch, it tries to pick up one of the following broadcasts:
- call sign JJY in Fukushima or Kyushu, Japan (60 kilohertz, Wikipedia article)
- call sign WWVB in Fort Collins, Colorado (US) (60 kilohertz, Wikipedia article)
- call sign DCF77 in Frankfurt, Germany (77.5 kilohertz, Wikipedia article)
- call sign BPC in Shangqui, China (68.5 kilohertz, Wikipedia article)
The watch dial has a status indicator (marked in green in the photograph above) which permits the user of the watch to see the status of the radio reception. The user can press a button on the watch and the second hand will jump to “OK” or “NO” to indicate whether the most recent attempt to pick up the time signal was successful (“OK”) or unsuccessful (“NO”). When the watch is trying to receive the time signal, the second hand jumps to the “RX” (meaning “receive”) position. A single complete frame of time code begins at the start of each minute, lasts one minute, and conveys the year, day of year, hour, minute, and other information as of the beginning of the minute.
Today (March 12, 2023) is a day (blog article) when it became necessary for the wristwatch to do one of its automatic DST adjustments. This morning I happened to be awake at about 1:58 AM and I got the idea of trying to make a video recording showing the automatic time change that this watch carries out. You can see it in this video. (I edited the video to remove some of the boring parts.) The wristwatch started trying to receive the WWVB time signal promptly at 2AM. It had to try several times to pick up the signal and it finally succeeded at about 2:10 AM, as indicated by the second hand jumping to the “RX” position in the status indicator. Shortly after that, the wristwatch adjusted its time from 2:10 AM to 3:10 AM.
If the embedded video player does not work for you, you can click here to watch the video.
This particular wristwatch is only 11 millimeters thick, which makes it quite a bit thinner (and lighter in weight) than most radio-controlled wristwatches.