7 ms·
So good, it works on barbed wire (2001)
- westurner 2y ago> In summary, the barbed wire had zero impact on signal quality. The signals went through perfectly undistorted. The only thing the barbed wire did was impress the heck out of Broadcom's customers. Next time you look at a transmission line, I hope you'll focus on the big four properties: characteristic impedance, high-frequency loss, delay, and crosstalk. These properties determine how well a transmission structure functions, regardless of the physical appearance or configuration of its conductors. FWIU from "The Information" by Gleick, Shannon entropy Shannon started out with digital two-state modulations on wire fences
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- mmastrac 2y agoEven with my electrical engineering degree, four years of hard math, signals courses and understanding all of this at an abstract level, it all seems magical to me when it works in practice. Thanks to all the tireless engineering of all the folks that manage to abstract this all away so we get clean zeroes and ones at the other end. I'm definitely a digital, logical, bits-type-of-guy.
- sour-taste 2y agoI certainly don't have your credentials but wasn't the point of the articles that it looked flashy while proving nothing about the capabilities of the chip?
- treflop 2y agoPretty much. If you took undergraduate EE, you would learn most of how to pull off Broadcom's trick when you learned transmission lines: https://en.wikipedia.org/wiki/Transmission_line https://en.wikipedia.org/wiki/Transmission_line Cool applications, but probably one of the more boring chapters IMO...
- Dalewyn 2y ago>I'm definitely a digital, logical, bits-type-of-guy. I think the fundamental takeaway from these stories is that even the digitalest of digital things still ultimately exist in an analog world governed by the analog laws of physics.
- cushychicken 2y agoOne of the fun parts of this is when you start realizing digital methods of improving analog signaling exist. He mentions one of these techniques briefly in this article: equalization. The condensed version is that you use an ADC for the receiver, sample the incoming waveform, then pass the resulting samples through a digital filter that amplifies the high frequencies and suppresses the lower frequencies. This is actually quite good at counteracting the losses and phase shakeups that come with passing high speed signals through long cables.
- helsinkiandrew 2y agoSurely, although iron has 1/6 the conductivity of copper, even if severely rusted there’s far more metal than the wires in a decent ethernet cable, and far more separation between them
- bee_rider 2y agoThey mention the distance in the blog post.
- Dwedit 2y agoHas anyone successfully run a faster protocol on Thinnet Coax Ethernet cable?
- amluto 2y agoIt has the wrong impedance for MoCA, and any long split-off sections might cause nasty reflections, but other than that, MoCA (possibly through an impedance matching transformer) ought to work fine.
- cyberax 2y agoYou can run 1GBps on it. There are companies that sell hardware for it, even specialized multi-port switches. They are mostly used to retrofit the old CCTV infrastructure for newer PoE-based systems. It's typically called Ethernet-over-Coax. E.g.: https://www.nvtphybridge.com/ https://www.nvtphybridge.com/ or https://www.dualcomm.com/collections/ethernet-over-coax/products/long-range-and-multi-drop-ethernet-over-coax-adapter https://www.dualcomm.com/collections/ethernet-over-coax/prod...
- nurple 2y agoIs it not also powered via common-mode voltage? Love how coax engineers are always stacking frequencies, including 0Hz.
- ssl-3 2y agoSimplified, Thinnet is just RG-58, and RG-58 is just coax that has a characteristic impedance of 50 Ohms, and 50 Ohm coax works just about like any other impedance of coax as long as the termination impedance is correct (or the length between terminations is 1/4 wavelength), and the attenuation is not too severe. One can send the whole RF spectrum down a single length of coax. The little pinkish-copper wires in your wifi gear are just coax. SATA cables: Also coax. Uncompressed HD video over SDI? Also coax. (But you asked about successes, not theory. I've run 5G cellular services through thinnet wire. Does that count?)
- topspin 2y ago
- mixedCase 2y agoIn the same vein of interesting experiments on weird cables: ADSL on wet string: https://www.revk.uk/2017/12/its-official-adsl-works-over-wet-string.html https://www.revk.uk/2017/12/its-official-adsl-works-over-wet...
- bee_rider 2y agoMakes you wonder what’s going on when you do get a crappy connection.
- Epa095 2y agoThe string is dry.
- Loughla 2y agoHonestly, before we had municipal fiber, I'm pretty sure our connection was wet string. Rural living does have its drawbacks.
- nick7376182 2y agoWhat is the impedance of a gopher's teeth?
- dfox 2y agoCrosstalk or other interference coupled from the outside into the line. The telco grade twisted pairs do not really behave like twisted pairs (that cancel out the external coupling) at the frequencies used by xDSL.
- Simon_ORourke 2y agoMy gawd, now I've seen it all! That's one step up from digital transmission via pigeon.
- kqbx 2y agoReportedly, ADSL can work even if there is a short (~5mm) gap in one of the conductors (because of capacitive coupling). source: Someone said this on reddit so it must be true https://www.reddit.com/r/networking/comments/7jj7ap/comment/dr6rihi/ https://www.reddit.com/r/networking/comments/7jj7ap/comment/...
- jp57 2y agoTl;Dr - ethernet.
- ksherlock 2y agoI was expecting the barbed wire / telephony story. https://www.atlasobscura.com/articles/barbed-wire-telephone-lines-homesteaders-prairie-america-history https://www.atlasobscura.com/articles/barbed-wire-telephone-...
- DeathArrow 2y agoBut does it work on wet rope?
- alentred 2y agoDon't know why are you being downvoted, perfectly correct assumption, in fact being discussed in another thread right here https://news.ycombinator.com/item?id=40476339 https://news.ycombinator.com/item?id=40476339 !
- mindslight 2y agoWhy does the demo title within the image say "Gigabit Ethernet"? Is that a marketing lie of what they had hoped to eventually achieve, with the actual demo running 100mbit? Or was the same demo repeated for (what would become) 1000Base-T?
- exmadscientist 2y agoI think those are two different demos, years apart (1995 vs 1998)? You're right that it's sure not clear.
- mindslight 2y agoAh, I had missed the author's caption on that photo dating it at 1998. Looking at it again, it's even more odd because the article was written in 2001 - meaning that the 100Base-T4 anecdote was twice as old as the gigabit demo photo. The part that stands out to me is the author writing off the high frequency loss because each pair is only carrying 25 mbit, yet Gigabit is ten times the bandwidth which is around where I'd think things would start to get a bit wonky. But maybe my intuition is still just the result of single conductor flapping around in free space, rather than a "controlled" impedance balanced pair.
- exmadscientist 2y agoGigabit brings in all four pairs, so it's only at 125 MHz, five times faster (which is in fact exactly why it does that). That's not all that much worse than 25 MHz. And as for intuition... Howard Johnson is something of the authority on signal propagation, so if he says that's what your intuition ought to be, I listen!
- mindslight 2y agoI'm just saying, scopes have a 20Mhz limiting switch for a reason and that's also around where I start to think something might be better off not on a breadboard. I recognize neither of those things is a controlled impedance pair. It just hits differently to write off 25MHz vs 125MHz as "low frequency".
- kaycebasques 2y agoGreat story. Seems like a prime example of "any sufficiently advanced technology is indistinguishable from magic." In this case the barbed wire was a sleight-of-hand trick. One day I'll dive into networking technology. It's fascinating to me how going down the OSI model layers results in such different goals, requirements, and constraints.
- kqr 2y agoAlso a prime example of the converse used by a university lecturer of mine: "If something seems like magic you're not asking enough questions."
- moffkalast 2y agoIf you think this is impressive look up Powerline ethernet, that shit is bananas. Though it's probably its own protocol with far more error correction.
- suroot 2y agoI’ll beat a bit of a dead horse with this one. This is why I’m not a big fan of water/pipe analogies when it comes to the study of electricity, electromagnetism and somewhere down the line electronics. While I understand early pioneers used “fluid” as a kind of hypothesis, I do not think they used them as analogies. I think they were trying to derive what was happening by comparing and seeing if their observations matched their line of thinking. All analogies break down relatively quickly the moment you attempt to work upwards from first principles (as we presently understand them which for all intents and purposes is “good enough” given we got many things to work just fine.) The reality of the situation is far more impressive and engrossing if we attempt to truly get a handle on what is happening. Only then can we have a clearer idea of the nature of things like impedance and where/why/how the formulas that we use are derived from.
- snakeyjake 2y agoThat analogy has gotten an uncountable multitude of people, including children, into electronics where "working upwards from first principles" is either not practical or impossible.
- jaredhallen 2y agoTrue. And many people don't care about the details. My wife, for example. She just wants to understand enough to wire up her derby cars. The water metaphor is perfect for those situations.
- suroot 2y agoIn light of me prefacing electronics by saying “somewhere down the line,” I don’t see the quality in this comment. While there are professions where half-way through you kind of have to go back to the early things you thought you knew, and examine them in a more educated light, I’ve yet to see one as egregious as this. Nobody past a certain very early cut off limit benefits from using water analogies, and there is a push in education right now to move past water analogies because too many students enter first year post secondary with, simply put, incorrect ideas, and it has teachers baffled.
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- AlbertCory 2y agoFunny, on some forum I was talking about DataPoint's ARCNet, and someone said they'd gotten it working on barbed wire. That must have been the final hurdle you had to jump over back then, or something.
- kqr 2y agoGoing over barbed wire was a common way to set up local telephone lines to the neighbours in rural U.S. So yeah, "does it work over barbed wire" may be a "yeah but is it still worse than the telephone?" question.