60 kHz (2022)
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60 kHz (2022)
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Re: 60 kHz (2022)
#2> 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"?
Re: 60 kHz (2022)
#3There 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...
Re: 60 kHz (2022)
#4> 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 sin…
US seems to be the first to pioneer this according to my very cursory research:
https://timeandnavigation.si.edu/multimedia-asset/us-navy-wi...
Re: 60 kHz (2022)
#5> 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 sin…
US seems to be the first to pioneer this according to my very cursory research: https://timeandnavigation.si.edu/multimedia-asset/us-navy-wi...
I stand corrected, it seems to indeed have been the US Navy that pioneered time signals. France followed up a few years later.
I don’t know who had the first system accessible to civilians, but at this point we’d just be arguing details.
Re: 60 kHz (2022)
#6the 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?
Re: 60 kHz (2022)
#7I can picture a room full of engineers in ties, wearing pocket protectors full of implements, chain smoking cigarettes while coming up with this one.
Re: 60 kHz (2022)
#8the 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 powe…
> By what, I wonder?
At that length of symbol encoding, by hand. :)
Re: 60 kHz (2022)
#9There 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...
In April one of the two WWVB antennas failed (broke) because of 90mph winds.
https://www.nist.gov/pml/time-and-frequency-division/time-di...
Re: 60 kHz (2022)
#10Pretty sure there’ll be lots of comments on this to do with bandwidth and speed of light.