Topic: New incorruptible time-stamp source? (Read 1078 times)

Yeah, I could easily be mistaken. My understanding was that all the high frequency noise that you system can't sample corrupts the low frequency noise you are trying to accurately sample, basically because filters are not perfect, but that understanding is second hand at best.


Yup... the amateurs find even off-the-shelf 2m dishes difficult to use to detect even known pulsars with lots of post-processing. Sun observation equipment could probably be done with something more like a sat-tv dish, which means the electronics are the hard part.


Good point re: GPS. People have even built GPS receivers from discrete parts and off-the-shelf uCs: http://lea.hamradio.si/~s53mv/navsats/analog.html


Doh, yeah you're quite right. (what can I say, I've never actually done any of this) Of course, an interesting question is what is the effective noise floor of the grid, or more precisely, what is the noise you'll measure local to you and not the other people capturing the signal.


Server doing better?

That has to be nearly dumbest thing I have read.
So I guess I will not be able to bit-mine off solar then?

Not so— the optical flux coming off the sun has tremendous RF noise.  I was mostly thinking of optical— simply because it's so much easier to get really strong spatial filtering— but I don't know if you've ever observed the RF output of the sun in 1-3cm, it's easily the hottest RF background source if you point a gain antenna anywhere near it and you can get reasonable gain at those frequencies.  I was assuming that the sampling would be synced with the system stabilized oxco and so should be fairly low (And consistent) in phase noise.

Of course, I haven't actually tried it for this. But I've absolutely done correlations of pure noise signals for range-finding and gotten usable results. Not every fix would be successful.

Picking up pulsars requires costly enough equipment... enough that it would sort of moot the decentralization of it. (Well if equipment to observe the sun isn't too exclusive)

Yup, the other problem is that few parties can observe more than one grid, so it would be hard to extend it world wide.   There is still the idea of securely timestamping the GPS signal though, which may still have value.


You're not limited to phase differences of 1/24KHz, assuming the anti-aliasing filters are correct— your phase resolution is only limited by the noise floor (quite excellent on modern sound cards) and jitter (not excellent, as you note).

(Of course, to get better phase resolution than just a fixed basis transform like the FFT will give you you'll need a fast non-linear solver for sinusoid parameters— but no worries, I've got you covered there: [er. link to be provided once the server comes back up]).

No, I have no clue who you are. I don't remember names that well.

Well, there's one more person for the ignore list...


Nice paper, although the idea of using the sun as your sample source is really flawed unfortunately. The problem is the noise the sun emits is basically just thermal noise, so while you can try to make a good measurement of it to do cross-correlation you'll find out that your phase information is screwed up because there is no way to distinguish what is the sun and what isn't. You'd have better luck using an optical telescope, but then you'd run into the problem that there aren't any features on the sun that change sufficiently fast.

What does work along these lines for time synchronization is to use radio telescopes to lock onto specific pulsars. Using multiple pulsars at once could give you enough information to resolve increasingly larger time intervals by comparing pulsars of different intervals and phase relationships. The requirement for a radio telescope though is a bit annoying...

However... the electrical grid on the other hand would work just fine as it's a specific signal with fairly large variations distributed over a wide area. But as you say, you need the POW chain consensus to assign significance.

Still I figure a cheap wall-wart with AC output - rather than the usual DC - and a resistor divider could be connected directly to a soundcard line-in port with no issues. With a standard 48KHz sound card you'll be able to resolve phase differences down to 1/24KHz, or 41uS, with some effort. In reality jitter in your sound card -> computer chain would be the limiting factor. Even professional sound cards have hundreds of uS worth of jitter. That said if what you want to measure accurately is external to the computer, you can just build some hardware that puts a pulse associated with your measurement on another channel of the same sound card and you can ignore the computer's timing jitter again, at least for relative measurements.

FWIW I'm thinking of setting up a series of those monitoring stations with the data uploaded to a public server. It'd let people use that forensic technique themselves. Of course, that goes both ways...

If you don't want to read what people think of your ideas then please don't post them.

Sadly your idea does not eliminate the need to have a proof of work. You still need an attack resistant mechanism to assign significance to time even if you have a universal time source, moreover, having a common timebase doesn't make transactions actually arrive at a common time... and finally the grid is not a secure reference as its frequency is in-fact frequently changed in response to load (though if you have an attack resistance significance attaching mechanism that point doesn't matter).

As a tangent, you may find interesting my little paper on how to use a POW chain consensus to turn any common reference signal/oscillator into a highly trustworthy clock: https://people.xiph.org/~greg/decentralized-time.txt

You need to think a bit harder about what exactly you are proposing and exactly how it would work... Here's a thought exercise for you: what's to stop someone from making their own recording of some grid fluctuations, archiving it, and replacing the grid hum in one sound recording with a different one from that archive?

http://www.bbc.co.uk/news/science-environment-20629671


And then could use an agglomeration of sources from different grids in different locales to verify time against each other also .... obviously mining would no longer be needed to prevent double spending.