> I’m not particularly patriotic, but this kind of thing feels particularly American.
??? America has no doubt done some very remarkable things (the moon landing, the first backward compatible color TV standard), but I don't think this is a notable example of that.
I think everyone in Europe was familiar with even wristwatches getting the time from "airwaves". At least in Germany, watches were a very common thing since the 80s (I think everyone old enough vividly remembers the many Junghans commercials on TV). The corresponding signal has been broadcast for many decades earlier, as it's no surprise that railroad and airplane networks were in need of a common time: https://en.wikipedia.org/wiki/DCF77
> But we had a problem, and we solved it with technology. And none of that fancy newfangled technology — we solved it using solid technology, the kind that you can touch with your hands and that buzzes in the airwaves.
There wasn't much "newfangled technology" around at the time. We essentially solved it using the simplest method there was at the time, at least I find it a bit hard to come up with a simpler one.
Also, what would be an example of technology that you can't either "touch with your hands" or that does "buzz in airwaves"?
the bandwidth is just enough to broadcast a single digit of binary every second.
I'd be interested in some more context on this. I think it's pretty clear that you can encode more than 1bps in a 60kHz signal, but I'm curious how the encoding was chosen. There's some more detail on it here:
https://en.wikipedia.org/wiki/WWVB#Modulation_format
The WWVB 60 kHz carrier, which has a normal ERP of 70 kW, is reduced in power at the start of each UTC second by 17 dB (to 1.4 kW ERP). It is restored to full power some time during the second. The duration of the reduced power encodes one of three symbols:
If power is reduced for one-fifth of a second (0.2 s), this is a data bit with value zero.
If power is reduced for one-half of a second (0.5 s), this is a data bit with value one.
If power is reduced for four-fifths of a second (0.8 s), this is a special non-data "mark", used for framing.
This is apparently the IRIG H encoding, which dates to the 50s and is probably designed to be easily decoded. By what, I wonder?
If I think about time an American nowadays the first thing that comes into my mind is GPS. What WWVB or DCF77 (and JJY) was back then is now GPS timing capabilities. Much higher precision but of course a higher complexity for the receiver. [1]
I don't know about WWVB and JJY but the German DFC77 is not only AM modulated but FM too allowing for a better accuracy.
There are several of these stations, they are maintained and operated by NIST. Two of them were almost shut down recently due to budget concerns:
https://www.radioworld.com/global/why-wwv-and-wwvh-still-mat...
I wear a Citizen “AT” [1] wristwatch daily. It not only keeps perfect time, because of its daily sync at 2am to WWVB, but it also never needs a battery change since it self charges from light. These two features make it the perfect zero maintenance timepiece IMHO, and it looks stylish too.
[1] https://www.citizenwatch.com/us/en/collection/mens-atomic-ti...
Sadly, WWVB is damaged. At midnight on April 7, 2024, WWVB's south antenna was disabled due to damage sustained during high winds. WWVB now broadcasts exclusively from the north antenna, at a reduced power of 30kW. This situation is expected to continue "indefinitely", presumably because of a lack of budget for repairs.
For those looking to hear what this sounds like without buying any radio gear, there are many public kiwisdr sites that can hear 60khz. It's a matter of choosing AM decoding and tuning to the particular frequency.
Many of these have user limits and time limits as well. Note that you can also hear WWVB on 2.5mhz, 5mhz, 10mhz, and 15mhz.
I have a friend with a 300' longwire antenna. A few weeks ago, after we were done repairing an old receiver that included VLF, he tuned in WWVB for me... checking it off my bucket list. It was interesting to hear the beeps of different lengths.
It came in surprisingly clear, in our Chicago suburb, especially since this was after the antenna issue on their end.
I remember my dad getting a solar-powered wristwatch that could tune in to the Western European equivalent of WWVB (DCF77, located in Germany) and adjust itself (respecting DST!) when I was a teenager.
Not that I'd regularly suffer from empty watch batteries or horribly incorrect time on my quartz watch, but I always found that extremely neat :)
WWVB data transmission format is described here:
https://www.nist.gov/system/files/documents/2017/05/09/NIST-...
The WWVB transmitter sometimes has surprisingly long propagation: https://blog.jgc.org/2021/07/receiving-wwvb-time-signal-in-p... and https://blog.jgc.org/2023/03/wave-ok-wwvb-time-signal-sets-m...
I can picture a room full of engineers in ties, wearing pocket protectors full of implements, chain smoking cigarettes while coming up with this one.
Decoding these signals should be a fun 1st project for Software Defined Radio. Google search shows several projects which did just that.
If you go below 300 Hz, you are probably into some hardcore top secret stuff: https://en.wikipedia.org/wiki/Communication_with_submarines
Assuming salt water, a 1024 Kb message should take around 3 hours to transmit.
This got me thinking of this video:
https://www.youtube.com/watch?v=IbUhA6Vt6Sk
"We just lost the most powerful longwave transmitter in Europe, and why that's kind of a big deal" (2023)
Slight Technology Connection vibes, really fascinating stuff.
I'm currently reading (1954) The Time Regulation Institute [1], which has as plot element a series of fines for people not having their clocks set correctly.
Upon my walls hang two "atomic clocks," identical, which utilize this 60 kHz signal to set each time. For some reason, they are consistantly not set to the same time! In Tanpınar's world, the fines would be laughably immense, updated daily, and intentionally frustrating!
In my present realtime world, it is just mildly frustrating.
--
Thanks for the background/technical information =D
[1]: https://en.wikipedia.org/wiki/The_Time_Regulation_Institute
I see there are cheap indoor wall clocks that are syncd with WWVB. But can't find anything that use gps instead. I am wondering why? Are the receivers too power hungry or the signals just too weak? I'd think going with a gps time sync would be a more future proof design.
I like the topic very much, but why did this very basic blog post get so many upvotes?
Could someone please explain why the low frequency means the bandwidth is limited to 1 bps? Why can't the signal be turned on and off more times per second to transmit at a higher rate?
Earlier this week I purchased a Casio Waveceptor watch. It features the ability to synchronize with this radio signal. I'm very happy with it. I was also happy with an early-2000s model for several years prior. The older one's receiver seemed to become unreliable after about a decade, possibly due to changes in the wireless spectrum over time. Overall, it was quite a reliable watch and so I have good confidence in this product line.
American patriotism set aside, I share the author's enthusiasm for these types of technology! The post's main focus on how we stand on the shoulders of giants is so true! It makes me happy and proud as well.
Another fascinating technology that we take for granted, is the possibility to travel with 280km/h in a train and still be able to receive digital bits and bytes. What kind of witchcraft would our grand-grand-grandparents have called that?
""I’m not particularly patriotic, but this kind of thing feels particularly American. Perhaps my imagination of American innovation is still set in the era of lunar missions and radio.""
Yes. From the first trans continental train, telegraph, up through landing on the moon. It does inspire a lot of patriotism, it was very 'can-do' time. Very innovative, huge public works. The old technology is still amazing.
1 bps on a 60 kHz carrier? That is certainly not the maximum possible data rate.
There are AM stations broadcasting at only two or three times that frequency that broadcast voice and music.
Perhaps they meant that it is the most practical for small receivers like watches.
BBC R4 Longwave is at 198 kHz (formerly 200 kHz). The transmitter at Droitwich has been broadcasting voice and music since 1934.
60 kHz is “long wave”, a frequency so low you could almost still hear. It's just thrice the upper limit of ~20 kHz for the human ear.
I love how my wristwatch eats sunlight at day (solar-powered) and drinks radio waves at night. Never has to change a battery and shows time as accurately as any internet-connected device that listens to NTP.
For the makers here, you can purchase cheap small modules that interface to any microcontroller, including most popular ones like AVR (Arduino), ESP32, etc. so that they can receive and decode time signals from WWVB or the European equivalent DCF77. Just search for "WWVB (or DCF77) module" at the usual online shops.
Slightly tangent: being substantively patriotic is cool. It should be cool. America has done some incredible things like this and I’m sure it’s not just Americans that find it cool.
This is completely incorrect. Time synchronization across the entire US is done via GPS, not radio signals.
It's kind of baffling that in 2024 there are appliances that exist for which I have to manually set the time, or at least have to go through some cumbersome IoT set-up process, that most likely is absolute garbage security-wise if it isn't actively acting against my interests (like those fridges that only work with first-party water filters).
Maybe I'm under-thinking this, but couldn't my Wi-Fi router just broadcast the current time (and time zone) every minute or so in an unencrypted fashion to all devices within range?
Well said. Simple, solid technology for the benefit of everyone.
Can you use this in basically the lower 48 with a long antenna?
Free RTC L48?
I looked into getting a wristwatch that uses this.
Wonderful post, thank you.
Pretty sure there’ll be lots of comments on this to do with bandwidth and speed of light.
> I’m not particularly patriotic, but this kind of thing feels particularly American.
Maybe that tinge of patriotism is why Americans don't even bother to see if something isn't an American invention - https://en.wikipedia.org/wiki/Time_from_NPL_(MSF) - they'll just claim it anyways since they barely read outside their borders.
Radio 4 would also like a word: https://en.wikipedia.org/wiki/Greenwich_Time_Signal