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60 kHz (2022)

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Re: 60 kHz (2022)

#151

Post by dusted »

tanepiper wrote: post #97

> 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

I was going to remark on this as well, but my observation is different: It strikes me as a very (old-school) American thing indeed. But not a modern American thing, if it was a modern American thing, it'd be privately owned, for profit with continually degrading quality and multiple incompatible "service providers" competing to trick people into their particular walled garden..

Re: 60 kHz (2022)

#152

Post by zaxomi »

ToValueFunfetti wrote: post #126
tanepiper wrote: post #97

> 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

>The first radio time signal, sent by telegraphic code, was broadcast in September 1903 by the United States Navy. Most sources list Navesink, New Jersey as the site of this broadcast, but the reference clock was located at the United States Naval Observatory (USNO) in Washington, DC. The first regularly scheduled time broadcasts began on August 9, 1904* from the Navy Yard in Boston. By the end of 1905, the Navy had…

And before radio, between 1880-1927, time was pumped throughout Paris in the form of compressed air using a network of pneumatic tubes.

Re: 60 kHz (2022)

#153

Post by yatopifo »

CPLX wrote: post #118
cjs_ac wrote: post #100

Earlier quoted context omitted.

The US Bill of Rights is copied almost word-for-word from English legislation: https://en.wikipedia.org/wiki/Bill_of_Rights_1689

In fairness, the United States is a breakaway region of Great Britain.

Afaik, not Great Britain which is Scotland, Wales and England combined. It was part of the British Empire when it broke away.

Re: 60 kHz (2022)

#154

Post by retrac »

eternauta3k wrote: post #93
YZF wrote: post #79

Earlier quoted context omitted.

We need to know the signal to noise ratio. Not just the bandwidth. 4khz is enough to carry much higher rates on residential phone lines...

Alternatively, it would be fun to see how much noise you can put into the signal and still decode it. Maybe using the knowledge of its structure, kind of how (I believe?) GPS reception works.

It's fun with software radio to take a long recording of a chunk of spectrum and do the fourier transform and plot it. There will be clear lines indicating carriers, even ones too faint to be heard over the static. Software can do the same trick for decoding a modulation (at the expense of latency in decoding). Modern tech allows a further neat hack here. If you have a very stable local clock (which any modern digital device does) you can correct for frequency errors in the transmission. Once the clocks are synced, you know exactly when the next symbol should be. And you know how much the transmitter frequency as actually received, is varying from what it should be. And since a convolutional coding with a pseudorandom number might be used, you also know what the next symbol will be (only a small number are valid in any state). With all that together, in effect, the decoder knows when and where the signal will be, and at least part of what it will look like, before it receives it. So it can be compared with what is actually received, making it possible to pick it up well below the noise floor. Just add some error correcting codes for robustness.

Amateurs have successfully communicated data between California and New Zealand on longwave using only 1 watt of radiated power at the transmitter. (But the baudrate for that is measured in hours per bit. And the receiving antenna was considerable.)

Re: 60 kHz (2022)

#155

Post by mschuster91 »

meindnoch wrote: post #110
mschuster91 wrote: post #96

Earlier quoted context omitted.

> 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 importantly many mobile devices already have a receiver built-in GPS chips are very very power intensive as the compute power involved to decode a signal out of something that would normally be way below the noise…

>Say you're a country at war like Ukraine - have the "emergency bit" on nationwide during Russian air raids so that receivers can listen for area-specific signals and blare horns if affected. And what would prevent Russia from continuously broadcasting this emergency bit to cause chaos?

> And what would prevent Russia from continuously broadcasting this emergency bit to cause chaos?

So what, all that would do in my scenario is drain the batteries of the civilian populations' alarms a bit faster as they'd keep their more power-intensive CPU awake.

Re: 60 kHz (2022)

#156

Post by wglb »

o11c wrote: post #85
V99 wrote: post #44

Earlier quoted context omitted.

They usually have an offset and a DST option. So in Arizona you'd choose -7/Off, and never touch it again. In Colorado you'll have to toggle DST twice a year manually, because it doesn't know the rules for when it starts/ends.

You shouldn't have to toggle DST manually; it's encoded at :57-58. That said, my clock stopped syncing for some reason, so ...

The one remaining clock I have took a hard fall, and no longer syncs.

Re: 60 kHz (2022)

#157

Post by [deleted] »

Dylan16807 wrote: post #94
YZF wrote: post #87

Earlier quoted context omitted.

The limit is Shannon's law which depends on bandwidth and signal to noise. A more advanced modulation technique can get more "information" through up to that limit. A song for this matter can just be considered information as well. So the answer is almost certainly yes, one can get more out of existing channels by upgrading the equipment assuming the current equipment doesn't approach the theoretical limit which is a…

> An FM radio channel has a bandwidth of 200Khz. How gratuitous with modern tech. FM needs tens of decibels of signal to noise ratio to sound reasonable, especially if you want stereo. But a digital signal could fit perfect audio into that range at less than one bit per Hz, which would let it tolerate radio noise that's as strong as the actual signal.

[deleted]

Re: 60 kHz (2022)

#158

Post by ansgri »

asix66 wrote: post #86

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...

Great watches, I'm a bit sad my Garmin Instinct spoiled more classic wristwatches for me — with GPS and a lot of sensors, and an actually functional flashlight, I cannot imagine giving up that valuable wristspace for a bit of added beauty (fortunately it looks decent with an aftermarket strap).

Re: 60 kHz (2022)

#159

Post by ProllyInfamous »

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

Re: 60 kHz (2022)

#160

Post by wiml »

Dylan16807 wrote: post #94
YZF wrote: post #87

Earlier quoted context omitted.

The limit is Shannon's law which depends on bandwidth and signal to noise. A more advanced modulation technique can get more "information" through up to that limit. A song for this matter can just be considered information as well. So the answer is almost certainly yes, one can get more out of existing channels by upgrading the equipment assuming the current equipment doesn't approach the theoretical limit which is a…

> An FM radio channel has a bandwidth of 200Khz. How gratuitous with modern tech. FM needs tens of decibels of signal to noise ratio to sound reasonable, especially if you want stereo. But a digital signal could fit perfect audio into that range at less than one bit per Hz, which would let it tolerate radio noise that's as strong as the actual signal.

You might be interested in Digital Radio Mondiale: https://en.wikipedia.org/wiki/Digital_Radio_Mondiale
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