I remember when I was a kid, my uncle got a brand-new alarm clock for Christmas. He plugged it in, and we watched it set itself! The numbers flashed around for a while and then suddenly — bang, it was the correct time. I remember being absolutely blown away and having no idea how this could work. The packaging said something about atomic clocks, which made me think of nuclear power and secret spy satellites.
Well, the truth is actually just as cool. This Atomic Clock AM Receiver Board uses the US’s time standards broadcast from Fort Collins, Colorado on the longwave station WWVB at 60kHz. This station broadcasts an immensely powerful longwave signal — 70kW! The frequency is locked to on-site atomic clocks, which are maintained and synchronized by NIST. Every minute, a pattern of 60 bits (one bit per second) is sent in a format known as IRIG H. This sends the year, the day of the year, as well as the hours and minutes. It also sends out warnings about upcoming leap seconds.
While GPS accomplishes the same thing, the simplicity and reliability of the longwave system means it is still used in almost all digital clocks, as well as many watches and other timekeeping devices. This kit allows you to integrate this accurate timekeeping from anywhere in the world — the time signals are also broadcast from Japan, Germany, and many other places too.
So get hacking with time and be sure to post your atomic clock projects on Hackaday.io!