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60 kHz (2022)

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Re: 60 kHz (2022)

#51
post #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 sin…

> 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 Not the 80s. The first radio controlled wristwatch came out in 1990 (Junghans Mega 1).

Sorry, I mistranslated “clock” (hence why I differentiated “wristwatch” in the sentence before). We owned a Funkuhr-Wecker in the 80s, so, an alarm clock synchronizing to DCF77, in the 80s. The wristwatches came a bit later, yeah (not that I’d have known without looking it up whether that was earlier or later than 1990).

Re: 60 kHz (2022)

#53
post #18
post #6

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 powe…

By "atomic" clocks (for example https://www.amazon.com/Crosse-Technology-WT-3129B-Atomic-Ana... ), and older brands of watches. I think there are also older industrial applications using this technology to syncronize.

Wow, added to wish list!

Re: 60 kHz (2022)

#54
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.

Re: 60 kHz (2022)

#55
post #35
post #12

Earlier quoted context omitted.

The signal is not 60 kHz wide. It is at 60 kHz. A pure carrier with no modulation has the inverse of infinite bandwidth. (Assuming perfect transmitters, which can't really exist, of course.) The faster you modulate the signal, the more it spreads out across the spectrum. The frequency-time tradeoff. The time signals run at the low end of longwave. That spans from about 40 to 120 kHz or so. There is about 100 kHz of s…

The agency running the German equivalent to WWVB, DCF77, has looked into piggybacking an emergency warning signal onto unused bits of the time signal: https://www.ptb.de/cms/en/presseaktuelles/journals-magazines... These days though, a more popular idea seem to be to piggy back onto GNSS signals, which are also broadly available (no idea how well they compare in practice to low frequency time beacons), and for which…

> a more popular idea seem to be to piggy back onto GNSS signals

Don’t all GNSS systems provide a highly accurate time signal (maybe needed for computing the distance to satellite)? I know GPS does at least.

Re: 60 kHz (2022)

#56
Decoding these signals should be a fun 1st project for Software Defined Radio. Google search shows several projects which did just that.

Re: 60 kHz (2022)

#57

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.

Well said. I couldn’t agree more.

I think there are a lot of countries that have done some really remarkable things. I’m American, and I’m generally very proud of my country. If I were, say, French, Swedish or Japanese, I’d feel the same way.

Obviously none of those countries - or any country - is perfect, and all have some distinctly dark chapters in their past, but there’s something inspiring about a society organizing itself to accomplish generally good things.

Re: 60 kHz (2022)

#58
post #6

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 powe…

> This is apparently the IRIG H encoding, which dates to the 50s and is probably designed to be easily decoded. By what, I wonder?

Wonder no more! This technology is used in wall clocks, weather stations, and even wrist-watches.

They're usually marketed as "atomic clocks".

Re: 60 kHz (2022)

#59
post #6

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 powe…

For those of us that are visual or audio learners: https://www.youtube.com/watch?v=V0CWj9DwRBY

Re: 60 kHz (2022)

#60
post #59
post #6

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 powe…

For those of us that are visual or audio learners: https://www.youtube.com/watch?v=V0CWj9DwRBY

And a "coverage map" https://www.nist.gov/pml/time-and-frequency-division/time-di...
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