15 ms·
ADSL works over wet string (2017)
- ksec 5y agoThere used to be a debate about going All-in on GPON or doing FTTX with G.Fast. Now G.Fast is pretty much dead or niche at this point. The end of DSL era. While DOCSIS is still doing well in many places. The next step would be to mandate fibre cables in all new housing. Along with ONT and Router in one solution.
- Nextgrid 5y agoBetter regulation around marketing would go a long ways to begin with. In the UK "fiber" is used as a catch-all term for any kind of internet connection even though in the majority of cases it's just fiber up to a certain point and then either DSL or coax, making it hard for consumers to tell exactly what they're signing up for. Same for bullshit terms such a "superfast" or "ultrafast" instead of actual up/down/latency numbers.
- traceroute66 5y agoWhy is this 2017 blog suddenly appearing here in 2021 ? Not surprisingly, it has already been covered many times: - https://news.ycombinator.com/item?id=15908107 - https://news.ycombinator.com/item?id=15922239 - https://news.ycombinator.com/item?id=26868780 The world has also moved on since 2017. Most people's question now is "how soon can I get fibre" not "how can I tweak my ADSL line to scrape some extra performance".
- agumonkey 5y agoSince seeing this article I've been curious about organic conductors .. apparently most carbohydrates / celluloses are really not good basis for conduction but maybe there are tricks to change that. - https://www.quora.com/Is-cellulose-fibre-conductive?share=1 https://www.quora.com/Is-cellulose-fibre-conductive?share=1 - https://duckduckgo.com/?t=ffab&q=conducting+polymers+examples&ia=web https://duckduckgo.com/?t=ffab&q=conducting+polymers+example...
- hashimotonomora 5y agoEssentially you need loose electrons to conduct.
- VHRanger 5y agoThat's not exactly correct. Electrons don't flow through wires - there's a one-way flow of the ambient electrons around the wire from the field created. See here: https://www.youtube.com/watch?v=bHIhgxav9LY https://www.youtube.com/watch?v=bHIhgxav9LY
- hashimotonomora 5y agoThat video is misleading. Electrons must be relatively loose in their orbitals in order for the electromagnetic field to be established with reasonable strength. This does not mean that electricity is the literal flow of electrons. However, electrons actually do flow at a speed of about 1 mm/min due to the electrostatic field in DC circuits. This is not what’s called electricity but they do flow.
- pjc50 5y agoWell .. they do flow in the conductor, and in particular they flow through silicon junctions or none of the semiconductor physics would make sense, but the energy is carried in the field which is indeed outside the conductor.
- NovemberWhiskey 5y agoYou're confusing the electrons and the electromagnetic fields. The electrons absolutely do migrate through the wires; the electric field does not. P.S. that video appears to have been written to confuse/generate controversy and does a terrible job of actually explaining.
- SV_BubbleTime 5y ago> The electrons absolutely do migrate through the wires; That’s true. But very slowly in electrical terms. If I remember right the actual electronics in a reasonable circuit I read about was something like 1” per second. The vast majority of work done is an electron shuffle of bouncing into the next one in space.
- sdflhasjd 5y ago3.5Mbit!? Says a lot about my parents paltry 1Mbit. Perhaps their line was low on sodium.
- iso1631 5y ago3.5mbit over 2 metres
- tyingq 5y agoThe cable analyzer is showing about 55db of loss across 2 meters. That's about equivalent to the loss across 4km of "good" copper.
- sdflhasjd 5y agoI kid, the issue was solved some time ago - a telecom engineer pinned it down to a soggy junction box.
- SV_BubbleTime 5y agoThat’s funny because my SO’s parents have 1.5Mbps DSL by contract. For only $100/mo they can jump up to 12Mbps. USA and 1 hour from me where I have gigabit docsis 3.1. If they had 1Mbps because of a fault that would be more unfortunate than unfair.
- ineedasername 5y agoThe awful state of US broadband. If you're not in the suburbs of a metropolitan area then broadband is (much more of) a crapshoot.
- cunthorpe 5y agoYour parents’ ADSL noodle soup is a little bland.
- ineedasername 5y agoPersonally I prefer a bit of garlic powder, say 1tsp, sprinkled over my router before any large downloads. Although last year when I bought Cyberpunk I found that a bit of curry powder sped up the ~70GB download quite nicely.
- codeflo 5y agoThat fact that this delivers 3.5 MBit/s really makes you wonder how many low speed connections out in the wild are literally broken cables that still have some amount of coupling somewhere.
- ajsnigrutin 5y agoA lot of the problem lies with distance. 10km of fiber (with transcievers made for that kind of fiber and distance)... gigabits without any issues. 10km of copper pairs for *dsl? Good luck.
- whalesalad 5y agoSums up my youth on ADSL in the hills of LA. Couldn't get a static IP address on coax/cable so I convinced my family to pay out the ears for speakeasy.net DSL w/ a static IP. Performance was terrible!
- someperson 5y agoPotentially apocryphal, but Telstra's copper cable network supposedly had its insulation made of paper, not rubber. I remember when it rained the curbside pits fill with water, causing slowdowns and frequent ADSL dropouts (until things dried out).
- tenebrisalietum 5y agoI think this is common in places where they don't expect moisture to reach, but then things change and it gets there anyway. If your POTS lines are down and the telecom company is telling you a "wet pulp repair" is underway, your phones are going to be down for a while because a bunch of paper-insulated cables need to be manually rewired because they got wet and corroded. I found this interesting: http://etler.com/docs/bsp-archive/629/629-295-300_I3.pdf http://etler.com/docs/bsp-archive/629/629-295-300_I3.pdf - guess it's standard practice to dry out the lines, wrap in cloth, put dessicant and then seal it.
- deleted 5y ago[deleted]
- fghorow 5y agoWet string? OK, fine. But I defy ADSL to work over something really challenging. Like Telstra copper in Australia.
- hedora 5y agoYou think the outback’s bad? Try getting it to work over AT&T copper in heart of Silicon Valley!
- zwayhowder 5y agoCame here to make the same joke. Sure it isn't an insightful comment worthy of great praise. But consider my hat tipped to you. 3.5mb down is faster than my mother used to get from her farm north-west of Kempsey NSW. Though to be fair to Telstra she lived about 30km from the nearest town not 2m like the length of wet string.
- fghorow 5y agoWhen I lived in Perth about a decade ago, I had a DSL line from an exchange about 3-ish km away. If I remember correctly, I got 512kbps down, and 56k modem speeds up. This was not outer-whoop-whoop either. Metro Perth. Telstra. Ya gotta love 'em.
- Faaak 5y agoRelated: ethernet over barbed wire: http://www.sigcon.com/Pubs/edn/SoGoodBarbedWire.htm http://www.sigcon.com/Pubs/edn/SoGoodBarbedWire.htm
- throw0101a 5y agoThere are IEEE standards for single-pair Ethernet: > In addition to the more computer-oriented two and four-pair variants, the 10BASE-T1,[17] 100BASE-T1[18] and 1000BASE-T1[19] single-pair Ethernet physical layers are intended for industrial and automotive applications[20] or as optional data channels in other interconnect applications.[21] The single pair operates at full duplex and has a maximum reach of 15 m or 49 ft (100BASE-T1, 1000BASE-T1 link segment type A) or up to 40 m or 130 ft (1000BASE-T1 link segment type B) with up to four in-line connectors. Both physical layers require a balanced twisted pair with an impedance of 100 Ω. The cable must be capable of transmitting 600 MHz for 1000BASE-T1 and 66 MHz for 100BASE-T1. 2.5 Gb/s, 5 Gb/s, and 10 Gb/s over a 15 m single pair is standardized in 802.3ch-2020.[22] As of 2021, the P802.3cy Task Force is examining having 25, 50, 100 Gb/s speeds at lengths up to 11 m.[23] * https://en.wikipedia.org/wiki/Ethernet_over_twisted_pair#Single-pair https://en.wikipedia.org/wiki/Ethernet_over_twisted_pair#Sin... Including power delivery: > The IEEE 802.3bu-2016[12] amendment introduced single-pair Power over Data Lines (PoDL) for the single-pair Ethernet standards 100BASE-T1 and 1000BASE-T1 intended for automotive and industrial applications.[13] On the two-pair or four-pair standards, power is transmitted only between pairs, so that within each pair there is no voltage present other than that representing the transmitted data. With single-pair Ethernet, power is transmitted in parallel to the data. PoDL initially defined ten power classes, ranging from 0.5 to 50 W (at PD). > Subsequently, PoDL was added to the single-pair variants 10BASE-T1,[14] 2.5GBASE-T1, 5GBASE-T1, and 10GBASE-T1[15] and as of 2021 includes a total of 15 power classes with additional intermediate voltage and power levels.[14] * https://en.wikipedia.org/wiki/Power_over_Ethernet#PoDL https://en.wikipedia.org/wiki/Power_over_Ethernet#PoDL
- toast0 5y agoSadly, there's not much in the way of equipment for this. I could really use two small 10BaseT-1 to 10BaseT converters, preferably both powered from one end.
- Eduard 5y agoOur homes' water supplies are untapped options for data connectivity.
- joncrocks 5y agojoking aside, I remember a while back that there has at least been cursory investigation into running high-speed internet cables through water pipes. Presuming you have water pipes to your property, could be easier than digging up roads etc. Only issue might be if you have a leak and need to shut off your water!! https://www.theguardian.com/technology/2021/aug/09/uk-launches-4m-fund-to-run-fibre-optic-cables-through-water-pipes https://www.theguardian.com/technology/2021/aug/09/uk-launch...
- Suchos 5y agoThere is company in Czechia which provides optics via sewage. I guess it is cheaper to use existing infrastructure than to place new pipes under roads.
- DaiPlusPlus 5y ago> I remember a while back that there has at least been cursory investigation into running high-speed internet cables through water pipes. Oblig: https://archive.google.com/tisp/index.html https://archive.google.com/tisp/index.html https://archive.google.com/tisp/install.html https://archive.google.com/tisp/install.html
- ixfo 5y agoThe linked article (and government push to do this) completely ignores the fact that this is done frequently now. It's used to get the last few metres into the home, e.g. from the boundary to the inside of the house. You put a swept tee in at each end, after the stopcock. Water off, dig down adjacent to stopcock, cut pipe, shove a drinking water rated duct down the pipe through the small port on a swept tee. Shove some chlorine tablets in the pipe and couple up to the new swept tee. Repeat interception at other end outside or indoors, and then use standard fibre cable blowing through the inner microduct, and away you go. There's a huge amount of disused water pipes in most developed nations which are frequently used, similarly using sub-ducting, and you can run cable through mains - but have to come out every time there's a valve, so practically it's usually cheaper to dig. Where it comes in handy is where there's areas you can't practically dig up, e.g. major roads with old pipes underneath. Source: Have done a bunch of this for a major UK telco. https://www.craley.com/craley-in-pipe-fibre https://www.craley.com/craley-in-pipe-fibre
- giardini 5y agoADSL, being essentially a form of alternating current, will pass through an air gap. I was enlightened on this by an AT&T tech who pointed out that one of my ADSL lines had several breaks and could not carry DC but the ADSL signal still came through. The other line was dead so I was running essentially on one wire with an earth ground. Here is an interesting discussion: "Phone line with 1 broken wire still gets ADSL2" https://forums.whirlpool.net.au/archive/9yzp5wr3 https://forums.whirlpool.net.au/archive/9yzp5wr3 Anyway, my hat is off to the people who designed and implemented ADSL.
- deleted 5y ago[deleted]
- geofft 5y agoIn some sense, that's "just" radio. An antenna is a wire... it's sending a signal and picking it up from a very nearby antenna. Radio transmissions are all AC. (Arguably, the real insight here is that the very existence of radio is impressive / unintuitive.)
- y04nn 5y agoThe gap on the line acts more as a capacitor than an antenna, AC pass through capacitors, but DC does not.
- Johnythree 5y agoIt's a differential signal using a center-tapped transformer to drive the signal. It's actually using three wires if you count the ground. This means it's symmetrical about ground and thus cancels it's own radiated field (eg doesn't interfere with adjacent lines). But with one side open there is still a path for AC, which is through the other side and using the ground return.
- DaiPlusPlus 5y ago> Anyway, my hat is off to the people who designed and implemented ADSL. It's a blessing-and-a-curse: too many incumbent ISPs in highly-developed nations used ADSL's ability to run on anything as an excuse to put-off FTTH deployments (looking at you, BT).
- stkdump 5y agoI guess my home internet connection as a kid used wet string then.
- nabla9 5y agoMost HDMI and Coaxial cables are little more than wet string https://ec.europa.eu/docsroom/documents/46433 https://ec.europa.eu/docsroom/documents/46433 >only 10% of the HDMI RMCD met an acceptable EMC quality of at least 50 dB coupling attenuation
- mmastrac 5y agoThe miracle of modern signal processing!
- Dylan16807 5y agoRMCD sure is an awkward way of spelling "cable". Especially when nobody else seems to use this acronym?
- derefr 5y agoCan ADSL survive an acoustic coupler? To give it a fair shot, assume the driver and microphone are studio quality rather than the kind you’d find on a 1970s telephone handset. I bet it’d work pretty well. But the real question would then be: how much of an air gap could you create and still get a connection? Could you post to HN on an ADSL signal that’s being screamed across the length of the room you’re sitting in?
- detaro 5y agoADSL upstream starts at 25kHz, downstream at >120kHz. So probably not. Purpose-designed ultrasonic hardware might be able to.
- londons_explore 5y agoOr an acoustic coupler which also acts a little like an electrical coupler at higher frequencies because it has no electrical shielding...
- codeflo 5y agoNot sure if this is within the spirit of the question, but: The individual ADSL bands are only 4 kHz wide, so you could modulate 4 or 5 of them down into the audible range (20Hz - 20kHz) and back up again after the transmission through the acoustic coupler. In theory, ADSL should then pick those bands to transmit the data.
- account-5 5y agoThis is the article I'm sending to Sky next time my broadband goes down.
- Nextgrid 5y agoGiven the state of some telephone cabinets and junction boxes that I've seen, your broadband most likely already has some wet string in the path.
- Shikadi 5y agoThat's impressive af!
- qeternity 5y agoThis thread is a good reminder to be very thankful for my £20/month unmetered 1gbit central London FTTH.
- dang 5y agoDiscussed at the time: ADSL over wet string - https://news.ycombinator.com/item?id=15908107 https://news.ycombinator.com/item?id=15908107 - Dec 2017 (88 comments)
- shireboy 5y agoI'm pretty sure this is exactly how my ATT DSL comes in.
- WaitWaitWha 5y agoI remember in the 90s when we were deploying a business campus, we first used ADSL services from the local carrier, but not for long. We discovered we can get "dry lines", basically just rent copper run from site-to-site, nothing on it from local carrier. Slap ADSL modems on each and we got max throughout, at a fraction of the cost. Then we upgraded to SDSL, and that was like hitting the jackpot.
- IntelMiner 5y agoI'm not sure if I'm reading this right. You got an unused copper line and stuck ADSL modems on both ends that talked to each other?
- WaitWaitWha 5y agoAlmost. Search "dry loop DSL" or "naked DSL".
- stefan_ 5y agoIf you want to try this at home, keep in mind that powerline is essentially the same thing - you don't necessarily need some DSLAM. Also these things spew so much RF they can frequently pair through thin air, just from radiated emissions.
- rob_c 5y agoHave seen this one a few times, still impressive
- techdragon 5y agoI’ll go one better, ADSL doesn’t even need two continuous wires to work, one is good enough as long as the other is just barely electrically coupled. I had a 12 month epic journey to get a performance fault fixed on my line. In the end it took 6 technician visits, three senior technicians and finally one smart experienced technician to check the “not in the textbook” faults for a performance degradation and he discovered that my line had was actually mis-wired! I had one wire connected to the exchange and another was a barely connected lose joint (actually disconnected but still technically in the plastic joint housing) about half way to the exchange. I was still getting a few megabits with intermittent drop outs for months on what amounted to a single wire!
- hereforphone 5y agoI think this relies on the particular string being a linear time-invariant channel. There is some limit where the string won't react accordingly (at a certain low or high frequency). What is that later phenomenon called, anyone know?
- NavinF 5y agoHmm the author had to use salt water to get it working. Maybe resistance is the limiting factor rather than dispersion. In which case a higher power modem or some sort of amplifier would get this working over >2m distances.
- robinduckett 5y agoThese guys are my ISP they're wonderful
- _8j50 5y agoIt works on chickenwire too, VDSL not so much. Back in the day when i installed internet lines customers with mandatory ISP service requirement by the gov with absolute shit outside or inside wiring got ADSL, forward-error-correction magic. VDSL was a lot more sensitive. In some cases I would be forced to use a cat-5 or even poor quality cat-3 where two pairs are for ethernet , one pair for A/VDSL and the blue pair for voice/POTS (voip to pots converted)
- oshiar53-0 5y agoThis is basically "near field" communication /s
- portportport 5y agoHonestly, any ODFM system is so incredibly resilient they will work over nearly any medium. I've tested powerline ethernet airgapped, and it still faster than the WiFI on the embedded system I was testing.
- Johnythree 5y agoAnd that is the problem with Ethernet over Powerline. Because the power lines are not balanced or shielded, most of the RF energy escapes and can cause serious interference to licensed radio services. And of course, if the interference can get out, it can also get in. Which is why Powerline Ethernet can work just fine one day, then suddenly stop working. Plus the big problem with any ODFM system is that it is incredibly intolerant of wideband interference, eg a series of sparks. The reason being that the band of ODFM channels are fed straight into an A/D converter without channel filters. So each time that wideband interference takes out the system, the modem has to stop and renegotiate each channel from the start. To any experienced RF engineer, Ethernet over Powerline (or any ADSL system) is a disaster waiting to happen.