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60 kHz (2022)

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Re: 60 kHz (2022)

#141

Post by spixy »

someguydave wrote: post #33
anyfoo wrote: 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…

Digital communications is America’s gift to the world, look up Claude Shannon

AC motor, steam, diesel, jet engines are european "gifts to the world",

yet it would be cringe to write sentence like "I’m not particularly patriotic, but this kind of thing feels particularly European"

Re: 60 kHz (2022)

#142

Post by esaym »

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.

Re: 60 kHz (2022)

#143

Post by ianburrell »

frankus wrote: post #13

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…

I have thought that Matter should have a time broadcast message that can be sent over Wifi, Bluetooth, and Thread. Which should be enough to set the time for any Wifi device that doesn't need NTP, and low-power devices with Bluetooth and Thread.

One problem is that need to pair with Wifi, Bluetooth, and Thread. The other problem is the cost to add time sync. And probably couldn't remove the UI for setting the clock because need it for people without technology.

Re: 60 kHz (2022)

#144

Post by asddubs »

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

inventing a solution to a problem, only in america

Re: 60 kHz (2022)

#145

Post by joezydeco »

lxgr wrote: post #63
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.

Oh, is there no “DST in effect” flag in the signal? As I understand it, the US switches at the same day across the country (for the states that do have it), so that should theoretically be possible.

The time code format does include a DST bit.

https://www.nist.gov/pml/time-and-frequency-division/time-di...

Re: 60 kHz (2022)

#146

Post by Liftyee »

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?

Re: 60 kHz (2022)

#147

Post by tanepiper »

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…

Yes but it's not "particularly American".

"In November 1898, an optical instrument maker and inventor named Sir Howard Grubb addressed the Royal Dublin Society and proposed the concept of a radio controlled clock."

It was already used in telegraph transmission.

America just implemented first.

Re: 60 kHz (2022)

#148

Post by benhurmarcel »

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

It’s like apple pie then

Re: 60 kHz (2022)

#149

Post by YZF »

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.

GPS is spread spectrum. It's modulated using a pseudo random sequence and then demodulated using the same sequence. All the same theory still applies but it's just a different way of using the spectrum, instead of a fixed band the bandwidth is "spread" across a broader band in a way that allows all these different signals to be multiplexed. Specifically with GPS IIRC the phase of the pseudo random sequence is also conveying timing information because of how it relates to the precise clock on the satellites. Spread spectrum can be a little more resilient to certain kinds of noise, e.g. if you have noise just at one frequency now you've reduced the impact of that noise.

Re: 60 kHz (2022)

#150

Post by mixmastamyk »

pohl wrote: post #132
mixmastamyk wrote: post #114

Earlier quoted context omitted.

A copy of the Magna Carta was in the National Archives for a while, and John Locke was a notable influence on founders such as Jefferson. Nihil novi sub sole.

I saw it there the day before yesterday!

Cool—I saw it once, and then it was gone a few years later. Maybe being serviced.
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